Revolution in Mobility

Electronics
WORLD
www.electronicsworld.co.uk
THE ESSENTIAL ELECTRONICS ENGINEERING MAGAZINE
April 2016
Volume 122
Issue 1960
£5.60
Teledyne LeCroy
Adds Revolutionary OneTouch
Gesture Control To 500MHz–4GHz
Oscilloscopes
SPECIAL REPORT
AUTOMOTIVE
ELECTRONICS:
Connectivity
Lighting
Advanced HMI
Vision processing
Technology
Mobile phone charge is
being extended
Regular Column
This is (Not) Rocket
Science
Motor control
Overview and basics of
different type of motors

CONTENTS 03
Cover supplied by
TELEDYNE LECROY
More on pages 8-9
05 TREND
Driver safety begins with code security
06 TECHNOLOGY
10 REGULAR COLUMN: MCUS
by Lucio di Jacio
14 REGULAR COLUMN: WIRELESS DESIGN
by Dr Dogan Ibrahim
46 PRODUCTS
18 REVOLUTION IN MOBILITY
Since the modern automobile was invented, its basic functionality
and shape have remained essentially the same. However, the
environment in which cars operate and the data they use to
enhance the driving experience are changing dramatically.
By Alan Amici, Vice President of Engineering for Automotive
Americas at TE Connectivity
22 STRATEGIES FOR IMPLEMENTING
AUTOMOTIVE LED LIGHTING SYSTEMS
By Fionn Sheerin, Senior Product Marketing Engineer at the
Analog and Interface Products Division of Microchip Technology
26 PROCESSOR EFFICIENCY AND
PROGRAMMABILITY FOR COMPUTE-INTENSIVE
VISION PROCESSING SUBSYSTEMS
Chris Rowen from Cadence Design Systems discusses the
ideal processor characteristics for supporting visual intelligence
applications
28 WAYS IN WHICH DRIVERS WANT MORE FROM
THEIR HMIS
The design engineer’s role is constantly changing in an effort to
create more intuitive and beneficial input methods for human-
machine interfaces. By Gary Baum, VP of Myscript
32 MEASURING HYBRID ELECTRIC VEHICLE’S
STABILITY WITH AN RT NAVIGATION SYSTEM
By Zhibin Miao and Hongtian Zhang from Harbin Engineering
University in China
36 A NOVEL FUZZY LOGIC MODEL FOR
INTELLIGENT TRANSPORT SYSTEMS
By Umut Ozkaya and Levent Seyfi from Selcuk University in Turkey
40 BASICS OF ELECTRIC MOTOR CONTROL
Stojce Dimov Ilcev from Durban University of Technology in
South Africa gives a comprehensive overview of different type of
motors and how to best control them
Disclaimer: We work hard to ensure that the information presented in Electronics World
is accurate. However, the publisher will not take responsibility for any injury or loss of
earnings that may result from applying information presented in the magazine. It is your
responsibility to familiarise yourself with the laws relating to dealing with your customers
and suppliers, and with safety practices relating to working with electrical/electronic
circuitry – particularly as regards electric shock, fire hazards and explosions.
REGULARS
FEATURES
28
40
32

TREND 05
Industry pundits will say that the top overall automotive story is cybersecurity. Each
month there’s a new vulnerability, report or demonstration of just how insecure
connected cars are. From in-vehicle infotainment system hacking to penetration through
wireless vehicle services, the number of potential attack vectors grows with every vehicle
model, yet the investment into improving cybersecurity at a fundamental level – the
software itself – lags behind.
It’s not hard to figure out why; according to a Ponemon Institute survey, 50% of
automotive developers are either unsure or don’t believe automotive software development
teams have the skills necessary to combat software security threats. Furthermore, over 50%
of developers are not convinced that their company prioritizes secure software development
or has the enabling technologies to support it.
Everyone from manufacturers to drivers wants secure software but can’t define a roadmap
to success. Software is where most errors are introduced. Not only has the volume of
delivered automotive code increased, the complexity and variety of architectures, platforms
and protocols has increased too, to where the permutations of state, behaviour, interactions
and outputs are well beyond a development team’s capabilities to test effectively.
The most crucial step is to transform teams so they understand vulnerabilities and know
how to build an efficient test framework. A relatively small investment in training is the
difference between a team that hides from the cybersecurity reality and one smart enough to
choose the right techniques and tools to mitigate risk.
A simple test is to ask developers to restrict memory reads and writes to specific
locations, preventing improper access to data. While the answer may be simple, it’s the first
step toward understanding that protection – and not performance – is the key to security.
Educating developers may take more time than some suppliers have, so it’s
worthwhile to investigate two familiar test techniques and adapt them to automotive.
First, while automotive teams have for some time been using coding and safety
standards, like MISRA and ISO 26262, adopting common, community-driven security
standards such as OWASP and CWE takes advantage of expert security guidelines to
quickly educate development teams on secure coding principles and provide a ready-
to-use measure of their code security. If these standards prove insufficient, creating
in-house, application-specific standards also provides a consistent, measurable
guideline for application security testing.
It can be said that some developers baulk at new standards, so the second familiar
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‘Application Security Practices in the Automotive Industry’ by the Ponemon Institute (www.ponemon.org)
“
Over 50% of developers are not convinced that
their company prioritizes secure software development or
has the enabling technologies to support it
test technique solves three problems at the same time: efficiency, adoption and
training. Automated testing has proved an effective way to offload common,
complex and, often, cumbersome work onto a controllable framework. Adapting
existing automated test-tools to include security verification adds little burden on
the developer but provides useful education around secure coding practices when
a test fails. It’s this unique win-win environment that makes automated testing so
valuable.
Bringing the benefits of automated testing into the modern development world
of continuous integration and agile methodologies has proven effective, allowing
organisations to deliver more robust features at a faster pace. These strategies put
the burden of common or complex development tasks onto tools that perform in
the context of frequent check-ins and builds.
When switching from traditional testing methods to continuous integration,
it’s critical to adopt tools to keep up with development velocity and pare down
vulnerability rates. The good thing is that some tools have changed the way
they work to fit incremental builds without requiring large investments in new
technologies or training. Testing by analysis has been around for years but
it’s only now that algorithm design and hardware performance is at the point
where analytic tools can perform all the checks they’re known for, security
included, against incremental builds.
Beyond education and technology, the most important point to remember is that
it pays to be paranoid. Working on the assumption that inputs to the system can’t
be trusted and that there are far more types of target environments than anyone
could possibly test for, serves to motivate more rigour in security testing and make
testing more efficient. And that’s the next step in automotive cybersecurity, after the
software developer has evolved to be a secure software developer − fitting in as
many comprehensive tests as possible so it’s less a question of whether the car is
secure and more a question of “what can we do next?”.
DRIVER SAFETY
BEGINS WITH
CODE SECURITY

06 TECHNOLOGY
April 2016
Fuel-cell technology firm Intelligent Energy
has joined forces with an undisclosed
smartphone OEM to embed hydrogen
fuel-cells into mobile devices to keep them
powered for over a week between charges.
£5.25M PROJECT PROMISES TO DELIVER WEEK-LONG
MOBILE PHONE CHARGE
In the near future, mobile phones will have embedded hydrogen
fuel-cells for longer-sustaining power charges
As smartphones become increasingly
loaded with more functionality and
processing demands, battery power is the first
to suffer, causing frustration for consumers.
“We believe embedding fuel cell
technology into portable devices provides
a solution to the current dilemma of
battery life. With consumers demanding
more and more from their phones, and
the advent of the Internet of Things
making the world more connected than
ever, battery innovation has not kept up.
What we offer is a solution that is clean
and efficient, and allows consumers to be
truly mobile and free from the constraints
of the grid,” said Julian Hughes, acting
Managing Director for Intelligent Energy’s
Consumer Electronics division.
Intelligent Energy has tailored a
development and integration programme,
costing £5.25m, for a specific smartphone
application to address battery limitations.
The programme will add embedded fuel
cells to an existing smartphone, resulting
in its licensing.
“We have been working with the
OEM over recent weeks, demonstrating
what our hydrogen fuel-cell technology
can achieve when embedded into a
smartphone,” added Hughes.

TECHNOLOGY 07
Cambridge, UK-based Plextek Consulting has
identified five key parameters necessary to make
driverless cars a reality.These are government
legislation, which must be passed to allow
autonomous vehicles on all public roads; insurers
need to accept the risks/implications of this new
level of connectivity and an entirely new model
for ownership that doesn’t make the driver/owner
responsible; manufacturers and service providers must
agree – as a partnership – to standards for resilience
to cyber-attacks; the automotive industry will need
to adopt international rules for interoperability that
ubiquitously apply across all manufacturers and vehicle
models; and manufacturers and service providers must
agree – again as a partnership – to standards for data
sharing via vehicle-to-vehicle (V2V) and vehicle-to-
infrastructure (V2I) communication.This last step also
requires end-to-end communication of critical/private
data to be authenticated by secure means.
Although many automotive companies and outsiders
to the industry,such as Google andApple,are publicly
committed to eliminating human driving in five years
and promising fully-automated vehicles for sale by 2020,
the road to autonomous driving is not a simple one.
DRIVERLESS CARS NEED GLOBAL STANDARDS
AND INTEROPERABILITY, STATES REPORT
“To realise the autonomous ‘dream’, industry
and societal stakeholders must be brought together
to discuss and resolve complex issues over safety,
security, reliability and liability to ensure this
revolutionary technology makes the leap from
concept to reality,” saidAndrewAshby,Automotive
andTransport Business Manager at Plextek
Consulting.
“To produce fully autonomous vehicle systems
where drivers or owners will reap the full benefits
− such as reduced journey times and insurance
premiums, and a healthier lifestyle − a whole new
level of integrated connectivity over and above what
Google calls an ‘autonomous car’ is a fundamental
requirement.”
Latest innovations are paving the way to
monumentally change the landscape of the
automotive industry, creating the biggest
transformation of society’s view of the vehicle in 120
years and a market worth some $42bn by 2025.
Driverless cars need global standards

08 SPONSORED FEATURE
April 2016
The new WaveRunner 8000 combines a superior
oscilloscope experience with an extensive toolbox to
shorten debug time. MAUI with OneTouch includes the
most unique touch features on any oscilloscope providing
MHz - 4 GHz of bandwidth, 40 GS/s sample rate, long
memory, and a versatile toolset make the WaveRunner
8000 unbelievably powerful and incredibly easy to use.
Superior User Experience with OneTouch
The WaveRunner 8000 with MAUI OneTouch sets the standard
for oscilloscope user experience by providing the most unique
touch features on any oscilloscope. Familiar touchscreen
gestures are used to instinctively interact with the oscilloscope
are optimized - all common operations can be performed with
one touch and do not require opening and closing of pop-up
dialogs or menus.
MAUI with OneTouch introduces a new paradigm for
oscilloscope user experience. Dramatically reduce setup time
with revolutionary drag and drop actions to copy and set up
channels, math functions, and measurement parameters without
channel, math or measurement using the “Add New” button and
oscilloscope operation.
Exceptional Serial Data Analysis
Isolate events using the serial bus trigger and view color-coded
protocol information on top of analog or digital waveforms. Timing
serial data system. Measurement data can be graphed to monitor
system performance over time. Identify physical layer anomalies
Unleash the power of serial data analysis to understand and
characterize a design, proving compliance, and explain why a
device or host fails compliance. The SDAII architecture provides
fast updates and eye diagram creation. Combined with up to 128
Mpts record lengths and complete jitter decomposition tools, SDA
II provides a fast and complete understanding of why serial data
fails a compliance test. Whether debugging eye patterns or other
compliance test failures, the WaveRunner 8000 Series rapidly
isolates the source of the problem. Advanced jitter decomposition
methodologies and tools provide more information about root
with the deepest toolset dedicated to providing the highest level of
insight into your serial data signals.
Very Powerful, Deep Toolbox
The standard collection of math, measurement, debug, and
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common design/validation scenarios. The advanced customization
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Our developers are true to our heritage – they are more
else. Our mission is to help you use these tools to understand
deep toolbox inspires insight; and your moment of insight is our
reward. Teledyne LeCroy provides more powerful, more unique,
and more standard tools than any other oscilloscope company,
and much of what is now “standard” in competitive products
originated at Teledyne LeCroy. Our tools and operating philosophy
are standardized across much of our product line for a consistent
user experience from 200 MHz to 100 GHz. Our MAUI advanced
powerful ways to solve unique problems.
Figure 1:
A. Channel, timebase, and trigger descriptors provide easy access to
controls without navigating menus
B. Conﬁgure parameters by touching measurement results
C. Shortcuts to commonly used functions are displayed at the bottom of the
channel, math and memory menus.
D. Use the “Add New” button for one-touch trace creation
E. Drag to change source, copy set up,turn on new trace, or move waveform
location
F. Drag to copy measurement parameters to streamline setup process
G. Drag to quickly position cursors on a trace
500 MHZ – 4 GHZ OSCILLOSCOPES WITH REVOLUTIONARY
ONETOUCH GESTURE CONTROL

SPONSORED FEATURE 09
to understand the toolsets that Teledyne LeCroy has created and
deployed in our oscilloscopes. Visit our interactive website to
Powerful Mixed-Signal Capabilities
With embedded systems growing more complex, powerful
mixed signal debug capabilities are an essential part of modern
oscilloscopes. The 16 integrated digital channels and set of tools
designed to view, measure and analyze analog and digital signals
enable fast debugging of mixed-signal designs.
Using the powerful parallel pattern search capability of
WaveScan, patterns across many digital lines can be isolated
time-stamped information, speeding up the search for each
pattern occurrence. Use a variety of the many timing parameters
to measure and analyze the characteristics of digital buses.
of all the digital lines simultaneously using convenient activity
indicators. Simulate complete digital designs using logic gate
emulation. When used with the web editor, many logic gates can
be combined in one math function to simulate complex logic
designs. Choose from AND, OR, NAND, NOR, XOR, NOT and D
Flip Flop gates.
Flexible analog and digital cross-pattern triggering across all 20
analog signal and trigger on a digital pattern.
QualiPHY
serial buses. It guides the user through each test setup, performs
each measurement in accordance with the relevant test procedure,
limits, fully documents all results, and QualiPHY helps the user
perform testing the right way
The following standards are supported: ENET, USB, DDR2,
Multi-tab Display Architecture
Unique Q-Scape multi-tab display architecture speeds up your
understanding of your design with 4x the display area. Acquired or
oscilloscope grid displays, with individually selectable grid styles
2160 pixel displays.
Advanced Customization
With the XDEV option, third party programs can be completely
or Visual Basic without leaving the oscilloscope application - and view
the results directly on the oscilloscope, in real-time.
M Models for Maximum Sample Rate and Memory
An industry leading 40 GS/s sample rate allows for a detailed edge
reconstruction even for signals with the fastest rise times. Long
memory allows for maximum sample rate to be maintained in longer
timebases. Deep memory of 128 Mpts is ideal for debugging long term
behavior on high speed serial data buses.
teledynelecroy.com/wr8000
Figure 2: WaveRunner 8000 combines Serial Bus Trigger, Decode,
Measure/Graph, and Eye Diagrams
Figure 4:
Compliance
Reports contain
all of the tested
values, the
speciﬁc test
limits and
screen captures.
Compliance.
Reports can be
created as HTML,
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Figure 3: Teledyne LeCroy provides more powerful, more unique, and more
standard tools than any other oscilloscope company, and much of what is now
“standard” in competitive products originated at Teledyne LeCroy.

10 REGULAR COLUMN: MCUs
April 2016
n a world of inexpensive high-resolution TFT
displays, the good old seven-segment LED
display looks positively ancient. However, there
are still many applications where the brightness
and contrast of an LED alpha-numeric display
cannot be beaten.
I was reminded of this quite recently, whilst
working on a home appliance application, where
we realized that a new feature called “Constant Current I/O drive”
microcontrollers, was going to help us save quite a bit of money.
to be a perfect excuse to play with this evaluation board and the
Constant Current Output Drivers
The new I/O structures introduced in the most recent generation of
output of each participating pin. The actual current limit value is
controlled by a single register (CCDCON) for the entire chip and can
be chosen from four possible discrete values:
Each pin can then be selected individually
to use that current limit when sinking
current, or driving the pin low with an
external device/load pulling up, or sourcing
current when an external device/load is
pulling down, or both.
The other, non-participating, pins will
continue to work as usual, driving as much
current as their loads require.
Granted, this mechanism does not
provide enough resolution to enable
sophisticated current-controlled sensory
applications, but it does drive LEDs
perfectly and, in this case, permits us to get
rid of the limiting series-resistors normally
required.
Removing a bunch of such resistors
would not seem like a big deal; after all, these days a small
board manufacturers appreciate the space saving and, more
importantly, the assembly-cost reductions, since the pick & place
time is directly proportional to the number of devices populating
a board, regardless of their initial cost.
A Homemade Click
and wired it up on a small prototyping board. I then cut it to the
board of sorts.
for example), because it comes already populated with additional
will come in handy for many future projects.
Simple Demonstration
will make use of the constant current output drive feature (set
drivers.
We will also use the on-board potentiometer to exercise the
duplicated on the two display devices for comparison.
most of all pins. The I/O driver Rdon
easily keep the maximum current below that value anyway, when
using a 3V power supply.
I
Driving seven-
segment LED
displays
BY LUCIO DI JASIO, MCU8 BUSINESS DEVELOPMENT
MANAGER AT MICROCHIP TECHNOLOGY
Figure 1: MPLAB Xpress
evaluation board

REGULAR COLUMN: MCUs 11
Quick Conﬁguration With MCC
URL (https://mplabxpress.microchip.com). Logging into your
MyMicrochip or MicrochipDirect account will complete the entry.
and a few mouse clicks to populate the project with the correct
initialization code for the device and all the required peripherals.
Here is the procedure I followed, step by step:
input function row.
proto board. I took notice of which one went where, and I
set to the Right.
the project sources. We are now ready to focus on the core of the
application.
In 10 Lines Of Code
Module table, although I expect this feature to become available very
soon. We will instead access the new control registers directly from
our application, which is CCDCON, to enable/disable and set the
the purpose:
when driving the output low (negative or sink current).
the output high (positive or source current).
Since I selected a common-anode LED display, in practice it is
when driving the segment outputs low that the current matters
registers, immediately after system initialization.
Figure 2: Seven-segment display
(common anode)
Figure 3: MCC pin manager

12 REGULAR COLUMN: MCUs
April 2016
void main(void)
{
{
}
}
Listing 1: Displaying the pattern for digit ‘1’ side by side
If all goes well, this simple pre-test should bring the message
is visibly higher than that of the controlled digit, proving that
current limiting is working.
Beyond 10 Lines Of Code
issues, there is an aesthetic problem with uncontrolled LED
more/all LEDs are turned on, the current in the uncontrolled LED digit
(truly limited only by the driver CMOS Rdon
characteristic) will divide
among the diodes, resulting in a lower perceived luminous output.
Simply put, as the pattern display changes, so does the luminous output
a constant luminous output from each segment as the digit displayed
changes.
To demonstrate this, we prepare a simple encoding table (matrix[])
pattern.
the correct LED segments requested, as shown in Listings 2 and 3.
Listing 2: Hex to 7-segment matrix
{
}
Listing 3: Hex digit translation
The complete application code is now a bit longer but much more
Figure 4: Pin module conﬁguration

REGULAR COLUMN: MCUs 13
void main(void)
{
{
}
}
Listing 4: Constant current drive, main.c
Figure 5: ADC conﬁguration
Turn the potentiometer and observe how stable the luminous
output produced by each display digit is as the information/pattern
shown changes.
In Closing
Constant current I/O drive is only one of the many new features
particular application it helps us save eight or possibly sixteen
perhaps most importantly it speeds up board manufacturing time,
These little improvements are not as revolutionary as the Core

April 2016
voice recognition system accepts a user’s spoken
words as inputs, interprets them as commands and
creates an action based on them. Simply put, voice
recognition gives a system the ability to listen and
understand.
Although voice recognition is not yet a perfect
home automation and some factory automation systems. For example,
a typical home voice automation system allows control of household
appliances, lights and other home systems by simple voice commands.
voice commands. Most voice automation systems are in the form of on/
response to voice commands.
The Advent Of IoT
With the advent of the Internet of Things (IoT) in the last decade,
ubiquitous computing has become very important in our daily lives,
making it necessary to simplify the human-machine interface using
is through voice. This idea can be extended to machines which can
easily and simply be controlled by the human voice.
The advantages of a voice-recognition-based automation
system are:
People with disabilities will be able to control their environments
Human convenience is increased since, for example, a light can be
Multi-lingual control is possible.
Voice recognition systems also have some disadvantages. Even
the most sophisticated system can make errors, especially if there is
closer to the speaker.
As shown in Figure 1, a voice-recognition-based embedded
automation system consists of two parts: the base station and the
A
Voice recognition in wireless
embedded automation
BY DR DOGAN IBRAHIM, PROFESSOR AT NEAR EAST UNIVERSITY, CYPRUS
Figure 1: Block diagram of the designed system
Figure 2: Block diagram of the example project

REGULAR COLUMN: WIRELESS DESIGN 15
remote station. The base station simply consists of a microphone,
speech-recognition module, digital processor and a radio telemetry
module. The speech-recognition module is usually programmable
in the sense it can be trained with words that the module should
recognise. Such modules have limited vocabularies, where the
duration of each word is also limited.
At the base station, upon recognising the spoken words, the
speech-recognition module composes the required commands
and sends them to the processor, usually in the form of serial
data. The digital processor is usually a microcontroller, which
upon receiving the commands, formats them and then passes
them on to the wireless radio telemetry module for transmission
to the remote station.
At the remote station, a compatible radio telemetry receiver
module receives the commands and passes them to the
microcontroller for processing and activation. In the simplest
and most common cases, electromechanical (or semiconductor-
based) relays are connected to the microcontroller output ports to
alarm, washing machine, microwave, television, radio etc. In more
advanced systems, sensors are used to determine the status of a
controlled device to ensure it has been controlled as desired. For
example, light sensors can be used to detect if the lights are on or
are in turn sent to the base station in acknowledgement. In such
applications a transceiver module will be required at each station
instead of a transmitter at the base station and a receiver at the
remote station.
Example Voice-Recognition Automation System
Figure 2 shows the block diagram of an example voice-
recognition-based automation system. At the base station a
SpeakUp Click board is used. This is a voice recognition module
The module has two operation modes: standalone and click.
The standalone mode is rather limited as it uses the on-board
STM32415RG microcontroller I/O interface. In this example the
click mode is used, with a very simple operation: words or phrases
a PC interface, and then assigned to commands.
In operational mode the module listens to spoken words and
matches the sound to one of the pre-recorded commands, and then
sends the index of the matched command to a selectable interface
(USB or UART). The microcontroller then activates the required
equipment based on this index.
A Clicker 2 for PIC18FJ microcontroller development board (based
on the PIC18F87J50 microcontroller operating at 8MHz) is used in
this example, with the SpeakUp Click board plugged-in to mikroBUS
socket 1 (see Figure 3).
The microcontroller sends the index of the recognised command
to an RF modem module (Figure 4). Although this project is based on
RF radio telemetry, it is also possible to use other communications
technologies, such as Wi-Fi, Bluetooth, ZigBee and others, a choice
use among others.
telemetry module receives the command and passes it to another
PIC18FJ microcontroller development board. A Relay Click
board is plugged into the mikroBUS socket 1 of the board. Relay
Click is equipped with two electromechanical relays where one is
Figure 3: Clicker 2 for PIC18FJ development board with the
SpeakUp Click board
Figure 4: TDL2A transceiver module
Figure 5: Circuit diagram of our example

In this example, the SpeakUp Click board is trained to recognise
the following words:
Motor OFF (index 3)
Training The SpeakUp Click Board
The SpeakUp Click board can be trained by using the freely
PC. Various parameters, such as recording timeout, word length,
noise level, data rate and the acceptance threshold can be set as
required.
tool. These commands are then assigned to actions that will be
performed when the voice is recognised. Also, a 16-bit index
number of the voice command will be sent via the chosen
communication interface (UART or USB).
commands, the project should be uploaded to the SpeakUp board.
The command names and their indexes are in the form of a source
The Circuit Diagram
The circuit diagram of this project is shown in Figure 5. At the
base station, the transmit pin of the SpeakUp board is connected
to UART2 input (RG2) of the development board, and the UART1
output (RC6) is connected to the radio telemetry transmitter. At
the remote station, the radio telemetry receiver passes the received
command to the second development board which then activates
the relays accordingly. In this project the base station transmits
and the remote station receives. Some applications may need to
send back acknowledgement to the base station when a command
has been implemented and the required action physically taken at
the remote station.
The Software
The software for both stations has been developed using the
mikroC Pro for PIC language and compiler. The base station
software is shown in Figure 6. At the beginning of the program
the two UARTs are initialised, after which the program enters a
loop. Inside this loop the program checks for commands from the
SpeakUp board and passes the received commands to the radio
telemetry transmitter module.
The remote station software is shown in Figure 7. At the
and UART1 initialised. The program then enters an endless loop
looking for a command from the radio telemetry receiver module.
activating the relevant relays. T
April 2016
void main()
{
//Endless loop
{
a command
byte of command
a command
byte of command
switch(indx)
// Send command to transmitter
{
case 3: UART1_Write_Text(“MOTOR
}
}
} Figure 6: Base station program listing
Figure 7: Remote station program listing
void main()
{
{
}
}

18 AUTOMOTIVE
April 2016
he connected car has the power to shake up the auto
industry as profoundly as Model T (also known as
Tin Lizzie, made by the Ford Motor Company between
1908 and 1927).
The implications for the connected car revolution and
the outlook for its growth are strongly positive. Market
analysis house IHS Automotive predicts that
sales of connected cars will grow six-fold globally
by 2020. According to Gartner, by then some
250 million connected vehicles will be on roads,
making connected cars a major element of the
Internet of Things (IoT). But, if connected cars,
equipped with Internet connectivity and sensor
capabilities that share information with many
sources inside and outside the vehicle, are to
become as feature-rich and reliable as forecasted,
car makers and OEMs must develop quality
connectors and sensors to make that connectivity possible.
Inside the vehicle, sensors provide feedback that can control
how and when a vehicle takes an action, from braking, steering and
throttle control, to warnings and route guidance. Outside the vehicle,
information is sensed and transmitted to determine position, speed, fuel
level, diagnostics and a wide array of other functions.
Driving The Connected Car Trend
There are several factors that drive the trend for connected cars, among
them safety, the environment and automation.
SINCE THE AUTOMOBILE WAS INVENTED, ITS BASIC FUNCTIONALITY AND SHAPE HAVE REMAINED
ESSENTIALLY THE SAME. HOWEVER, THEIR ENVIRONMENT AND THE DATA THEY USE TO ENHANCE THE
DRIVING EXPERIENCE ARE CHANGING DRAMATICALLY. BY ALAN AMICI, VICE PRESIDENT, AUTOMOTIVE
ENGINEERING AT TE CONNECTIVITY
T
can also be dangerous when driven unsafely. Over one million people
die globally every year in automotive accidents, and they are the
most common killer of people aged 10-24. In the US alone there
were more than 2.3 million people injured in car accidents in 2013,
(NHTSA).
Even though cars have themselves
become much safer over the past 50 years,
drivers are still the weakest link in the
safety continuum: research shows that
90% of vehicle accidents are caused by
human error. World agencies that govern
automotive safety are recognizing that
and injuries. The ‘New Car Assessment
Program’, supported globally and aligned
with the NHTSA, measures collision safety for car occupants and
is now focusing on advanced driver assistance systems (ADAS)
technology to help better avoid collisions.
Five Levels Of Automation
automation:
1. No Automation (Level 0), where the driver is in complete and
sole control of the primary vehicle controls at all times, including
braking, steering, throttle and motive power.
“
Even though cars have
become much safer over the past 50
years, drivers are still the weakest
link in the safety continuum: research
shows that 90% of vehicle accidents
are caused by human error
REVOLUTION IN MOBILITY

AUTOMOTIVE 19
stability control or pre-charged brakes, where the vehicle automatically
assists with braking to enable the driver regain control of the vehicle or
stop faster than possible by acting alone.
3. Combined-Function (Level 2), where automation covers at least
two primary control functions designed to work in unison for driver
release. An example of such combined functions includes adaptive
cruise control in combination with lane centering.
4. Limited Self-Driving Automation (Level 3), where automation enables
the driver to give up full control of all safety-critical functions under
vehicle to monitor for changes that may require the driver to take back
control. The driver is expected to be available for occasional control,
limited self-driving automation.
5. Full Self-Driving Automation (Level 4), where the vehicle performs
all safety-critical driving functions and monitors road conditions for
an entire trip. Such a design anticipates that the driver will provide
destination or navigation input, but is not expected to be available for
control at any time during the trip. This includes both occupied and
unoccupied vehicles.
Environment
As with safety, vehicle makers, working with government regulators,
have made tremendous strides in reducing polluting emissions
from cars. The automotive industry is currently working to reduce
greenhouse gas emissions, with a focus on vehicle weight, fuel
making cars more environmentally-friendly. Better driving habits
can be enabled by data-awareness of both a car’s performance and
increase carbon dioxide (CO2) emissions and drive up costs, including
costs of combating pollution. In the European Union, €80bn is spent
annually due to congestion.
The EU is targeting all new cars to emit less than 95 grams of CO2 per
kilometer by 2021, a 40% reduction on 2007.
A key link between connected cars and greener cars is more
infrastructure, they use less fuel and hence pollute less, because there is
Lifestyle
Nowadays, consumers are used to connectivity everywhere they go and
expect the same from their cars. As greater connectivity permeates their
homes, such as home automation and kitchen appliances sharing data
and being controlled by apps, they not only expect the same convenience
and access in their cars, but anticipate their connected homes also to sync
with their connected cars.
There’s a school of thought that connected cars can help people drive
conditions so they can steer clear of congestion, or choose safer
routes in case of weather issues. Drivers will seek out tools that
carpooling and how many miles it is to reach the next service or
charging station.
OEM Criteria
As vehicle manufacturers shift resources toward technology
inside the car, they must focus on three market drivers: safety,
environmental requirements and lifestyle expectations. This will
require a far more complex combination of hardware, software and
connectivity. For example:
1. Robust and reliable connectivity and sensor technologies;
2. Core connectivity – essential, seamless, power signal and data;
3. Reliable performance in harsh environments, such as extreme
temperature variations and vibration in rugged terrain;
4. Miniaturization – ever-smaller, lighter and modular components;
6. Faster data transmission, which consumers have come to expect
in their connected homes;
7. Sensing for improved performance and monitoring.
Connected For Safety
An increasing level of automation means a growing need for more
networking of all onboard systems, as well as sensors. Innovators in
Automoated cars will take
over driving in poor weather
conditions
Cross-section of a car
with its many systems

20 AUTOMOTIVE
April 2016
ADAS, such as headlamps that help drivers see the road better,
collision avoidance systems that automatically apply the brakes,
a shift from warning systems to avoidance systems, and sensor
solutions for fully automated control.
As consumers push for real-time data in their cars, car makers and
technology providers need to guarantee data speeds and availability.
For example, vehicles must respond immediately when a transmitted
reaction time must be a fraction of a second. Connected-car systems
must be able to transmit a full gigabyte of information per second
under high-vibration conditions to be considered reliable.
To contribute to safety, connected cars must also share
supplementary information from WLAN or mobile telecommunication
channels between the onboard electronic devices and the
infrastructure (V2I) or other vehicles in the vicinity (V2V), which will
Connected cars can enhance driver and passenger safety even
further. For instance, they can send alerts when children or pets are
mistakenly locked inside an overheating car; they can send panic
alarms in case of accidents or other unsafe situations; or can include
geo-fencing options that send car owners a text if the vehicle travels
beyond a set boundary.
Connected For Green
Everybody agrees that if we are committed to improving air quality,
reduce the time cars are on the road, and also requiring less fuel to
For example, it is estimated that 25% of city driving typically
involves just searching for parking spaces. By building parking
cars much faster. In addition, power management technologies and
systems are closed-loop control and require sensors.
Environmentally-friendly driving can also be enhanced by advanced
Figure 1: The evolution of autonomous driving
manufacturing techniques. A vehicle’s weight can be reduced by
C02 emissions. One tactic for using less material in a vehicle is to
miniaturize its components. In addition, the use of aluminum and
connectivity solutions in vehicles can reduce weight.
As automakers go lighter, they must give extra consideration to
areas of the vehicle such as the body, drive systems, chassis and on-
board electrical systems. Higher temperatures and vibrational loads
require improved and innovative terminal and connector systems.
Connected For Lifestyle
To bring car owners the features and functions that optimize
driver comfort, improve navigation and guidance, and deliver
entertainment, car makers must work with technology vendors
to create in-dashboard applications that provide cloud-connected
information and services to drivers and passengers. These
systems are often referred to as “telematics”, and provide two-way
communications – to and from the vehicle.
These lifestyle and convenience features not only keep car
occupants better informed and entertained, but they can also boost
productivity. When connected cars eventually make the leap to
self-driving vehicles, drivers can become more productive, using the
time spent in the car for something other than paying attention to
Potential Roadblocks
Whilst technologies and capabilities are in place – and evolving – to
deliver on the connected car of the future, other factors must be
addressed in this ecosystem. These include:
1. Security and privacy: The exchange of data among
applications in the vehicle and other systems, such as over Wi-Fi
and to connected home systems, raises issues about how this data
is protected. OEMs and vehicle makers must include safeguards
by making the connected applications and devices less vulnerable
to hacking.
2. Internet access: There is currently a limitation in place, since
liability for accessing data across geographies has not been
this may not be an issue for countries like the US or China for
example, it may be in places like Europe, where there may be
many countries within a certain driving range.
3. Infrastructure:
must take roadway investments into account.
4. Autonomous driving buy-in: To embrace the idea of
self-driving cars, consumers need assurance that they are safer
than driving the cars themselves. Automakers must prove that
autonomous vehicles operate with near 100% reliability.
5. Economics: Connected car advances must make good
economic sense for car buyers – or connected cars will be seen as
a luxury innovation, available to only a select few. Connectivity

22 AUTOMOTIVE LIGHTING
April 2016
ith advances in LEDs and their control, vehicle
manufacturers have been moving away from halogen
and incandescent bulbs. Dome lights, LED backlights,
turn signals (Figure 1), headlights, fog lights, tail
lights, accent lights and even infrared sources for
driver assistance systems can all be implemented with
consumption, improved vehicle aesthetics and brighter lighting.
However, these diverse systems have equally diverse control
the best performance from each lighting application.
New Trends
New vehicle designs contain more lighting than ever before, inside
and outside the cabin. Replacing incandescent dome lighting
and display backlighting with LEDs that will last for decades
is an easy switch, but replacing critical, legislatively-mandated
requires legislative changes. Novel, intelligent control schemes are
able to do completely new things with LEDs, and this is rapidly
revolutionizing automotive exterior lighting.
This trend started with the LED daytime-running lamps on
the 2004 Audi A8, which expanded to full LED headlamps on the
2007 Audi R8, and now complete LED exterior front lighting is
BY FIONN SHEERIN, SENIOR PRODUCT MARKETING
ENGINEER AT THE ANALOG AND INTERFACE PRODUCTS
DIVISION, MICROCHIP TECHNOLOGY
W
available on a wide range of production vehicles around the world,
including Cadillac, Audi, BMW, Mercedes-Benz, Toyota, Jaguar,
Volkswagen and many more; see Figure 2. OSRAM announced that
automotive standards is a very rapid industry shift.
of LED lighting compared to halogen and high-intensity discharge
(HID) lighting; the price of high-brightness LEDs is falling rapidly
and the reliability of the diodes is unmatched. However, the primary
driver of LED adoption is controllability, which requires intelligent
LED drive circuits. Lastly, and perhaps the most important element
for many consumers, are the aesthetics.
Lighting is an important vehicle design element and users are not
only easily frustrated by poor lighting but they ask for aesthetically-
pleasing lighting, and in many cases are willing to pay extra for it.
Manufacturers like HELLA, Automotive Lighting (Magneti Marelli),
Koito and Valeo are responding to these needs, since due to their
safety, reliability and curb appeal, good LED-based lighting designs
prices.
Safety First
Administrators and legislators are particularly interested in vehicle
exterior lighting. In most parts of the world, the number, brightness
and colour of exterior lights are mandated. Lights that are too
IMPLEMENTING
AUTOMOTIVE
LED LIGHTING
SYSTEMS
Figure 1: LED signal light, mounted on a
mirror for increased visibility

AUTOMOTIVE LIGHTING 23
bright for the road conditions cause glare problems, while dim or
failed exterior lights pose a safety hazard. Commonly, jurisdictions
have legislated acceptable brightness ranges for daytime-running,
low-beam (dipped-beam), high-beam, turn-signal, cornering and
fog lights on the front of the vehicle, with similar requirements for
rear vehicle lighting. In some cases there are also rules about which
lights can be used in what conditions, including whether lights need
to auto-level to compensate for road angles, and the speed at which
cornering lights turn on. This is a nightmare of design requirements,
which would necessitate a multitude of traditional halogen and HID
arrays of LED lights can address many of these requirements, if well-
designed constant-current regulators and intelligent architectures are
used. Good LED drive circuits are reusable, and the electronics can
be replicated into multiple designs. Microcontrollers built into the
headlamps can use information from light and temperature sensors
to adjust LED drive current, maintaining consistent light output, or
deliberately refocusing the beam or adjusting brightness in response
components. In addition, brake, hazard and turn-indication lights
can light up in patterns or sequences to make them more noticeable.
And last but not least, properly implemented LED lighting can turn
250ms delay with a standard incandescent bulb.
will be at reducing vehicular accidents in the long term, but they look
very promising.
Reliability
The inherent reliability of LEDs is also a major advantage over
previous lighting generations. With some LED manufacturers
claiming device lifetimes exceeding 20 years, it is conceivable that
in the future vehicle lights would not require replacement. Factory-
installed lights could last as long as the power train, without requiring
maintenance.
LED-based lighting systems can also be designed with inherent
reliability. Placing multiple independent lighting strings into a brake
light, such that damage or failure would merely reduce the light
more advanced electronics can add fault-reporting capabilities, so the
lights’ status can be displayed on the vehicle dashboard or reported
through the diagnostic code reader.
With the lighting systems attached to CAN, LIN or similar
in-vehicle communications bus, the car could warn the driver
if the lights are not functioning correctly. Chip makers such as
Microchip already make a variety of CAN and LIN transceivers and
microcontrollers that can be used for this application. This is not a
new concept, as CANBUS-compatible lighting has been available
in certain vehicles for a long time. But the older systems are only
low-power replacement bulbs commonly cause false errors.
However, with intelligent LED drive circuitry, it is possible to
report more detail than just complete failure. Lighting systems
voltage shifts, temperature changes, or even input-voltage shifts.
Diagnostic data could indicate future failures before they occur,
even detecting minor changes such as a single shorted LED in a
long string.
LED Drive And Monitoring Circuits
In order to properly apply these diagnostic features, the LED
drive and monitoring circuit must be as reliable as the diodes
it controls. Often, LED-based lighting systems contain more
components than the legacy bulbs they are replacing. Each extra
component in the system introduces another possible failure
Figure 2: LED-based headlight design, with independent strings
for multiple lighting functions
Figure 3: LED-based taillight with redundant light sources

AUTOMOTIVE LIGHTING 25
point. So, getting the full lifetime from an LED requires a proper
conditions.
For superb light quality and reliable operation, the drive circuit
should compensate for changes in temperature,
input voltage and load resistance, maintaining a
constant output current in every circumstance. In
order for a taillight to function for 20 years, both
the LEDs and their drive circuit must last for 20
years. This kind of regulation and longevity are
not possible using bias resistors. Lighting systems
must use tightly-controlled DC-DC regulators
to achieve long-term reliability. Microchip
manufactures several Digitally Enhanced
communication interfaces. Designed properly, the lighting system
high-reliability devices.
Selected By The Consumer
Safety and reliability are certainly desired features, and automotive
perceive as unsafe or unreliable, and then choose vehicles based on
fog lamps for a luxury sedan, the visual appeal
of exterior lighting is every bit as important
as the body or interior styling. Despite all the
safety, reliability, cost and longevity concerns,
for many drivers the vehicle is as much a
safe transportation; emotional appeal sells
cars.
Today, some car makers and tier-one
suppliers can be concerned about the added
cost of increased semiconductor content in
their vehicles, but the reality is that most of those electronic
features are adding far more value than they cost to implement.
path of vehicle automation, and an important opportunity for
the automotive industry to prove it can add safety, increase
reliability, improve ascetics and, ultimately, increase the
overall value of its vehicles.
“
OSRAM announced
that it expects one in ﬁve
headlights to be LED-based by
2020, which is by automotive
standards a very rapid industry
shift

26 VISION PROCESSING
April 2016
erformance demands for vision processing are
exploding. From pedestrian detection systems on
cars to facial recognition in social media apps, vision
processing is increasingly about extracting useful,
actionable information from a given image stream. As
a result, vision processing is highly compute-intensive
and calls for a processor with architecture to handle high-bandwidth
Consider the example of advanced driver assistance systems with
everything from rear-view cameras to blind-spot detection, parking
assistance and driver monitoring. In a short time, we’ve seen peak
processor rates for automotive vision platforms rise from about
100 giga-operations per second (GOPS) in early 2014 to more than
2000 GOPS in late 2015.
Indeed, vision processing may be the most compute-intensive task
in embedded systems, involving high sample rates and enormous
computation per pixel. Systems are now commonly equipped with
multiple cameras capturing visual data, with the end goal to not only
extract images, but obtain useful information about events in the
image stream, such as identifying people and objects and detecting
motion.
Balancing Act
Moving from simply processing pixels to enabling visual intelligence
calls for a new kind of vision instruction-set design. In these designs,
there is tension between the desire for maximum throughput and
on the other. Conventional wisdom holds that hardwiring, not
hardwiring whilst still maintaining programmability.
There are several key features to look for in an instruction set
architecture (ISA) for a vision processing subsystem:
It should handle voluminous data rate streams, moving data in
and out of processors with high local memory bandwidth and low
latency;
operations (2D data access, histograms, convolution, search, non-
linear functions);
EFFICIENCY AND PROGRAMMABILITY OF
PROCESSORS FOR COMPUTE-INTENSIVE
VISION PROCESSING SUBSYSTEMS
P
It needs to support sustained operations per cycle from a
combination of very long instruction word (VLIW) and single
instruction, multiple data (SIMD);
Scalability is key: as the needs of the application grow, the platform
needs to grow with it and so should the software environment to
address a range of cost and performance goals;
Automatic compiler inference of vectors and complex operations is
also a valuable asset.
the needs of a wide range vision-computing system designs. A single
vision computing applications.
ISA Flexibility
For vision computing, there is a wide range of available application
Collectively, these application kernels are quite diverse in terms of
operations, how many are multiplies, and so on.
An intensive analysis of 50 real-world application kernels reveals
store ratio is generally 1:2 to 5:1. Many important functions don’t do
multiplies, while a fraction have heavy multiply usage (convolutions
are an example). A good vision-computing ISA should be able to
A successful architecture also maximizes the fraction of kernels
that can be vectorized. There is a big opportunity here to vectorize
applications, i.e. work on a whole strip of pixels at a time in a single
cycle. You can often take advantage of the fact that what is done at one
pixel is typically dependent on what happens at adjacent pixels. The
vector processor can then run applications up to 50X faster than a
scalar processor can. (A small number of functions may still use scalar
operations heavily.)
When you’re trying to operate on a whole strip of pixels, you won’t
always want to operate on them in the same order or groupings in
which they appeared in memory. Instead, you might want to operate
on, say, every fourth pixel.
Operations in the instruction set that can reorganize data on the
CHRIS ROWEN FROM CADENCE DESIGN SYSTEMS DISCUSSES THE IDEAL PROCESSOR CHARACTERISTICS
FOR VISUAL INTELLIGENCE APPLICATIONS

VISION PROCESSING 27
vectorization.
Example: Convolutional Neural Network
In automated machine learning convolutional neural networks
(CNNs) are becoming a widely used general technique for pattern
recognition. CNNs are roughly analogous to functions of the brain.
Just as locally receptive visual cortex cells sample a small region
of the visual domain and detect a set of primitive features, we can
organize a set of parallel convolution computations to respond to
of convolutions take these primitive features as inputs and compute
higher-level features.
Convolutional neural networks with 5, 10 or even 20 layers of
convolutions have proven capable of recognizing large sets of objects
with high accuracy. Image processing is one of the most important
applications for the CNN, where individual neurons are tiled to
While neural networks have been around for decades, automated
techniques have only recently emerged to train these networks
to recognize almost anything. Obviously, such a task is extremely
computationally demanding, involving performing numerous
convolutions at every location of an image in order to generate a
sophisticated and meaningful pattern. It is through this layer-to-layer
processing that a vision computing system can distinguish between,
lighting conditions.
Happily, a well-designed vision instruction set lends itself well
to CNN computations, as the core convolution kernel is strikingly
processing. Moreover, no complete vision system is likely to rely
recognition functions, a more versatile data-parallel instruction is
needed for image enhancement, scaling, data conversion, warping,
noise reduction, depth processing and extraction of 3D structure from
images.
Configurable Processor For Vision Computing
A good vision-processing architecture supports a wide variety of
operations and precisions. Consider, for example, a pedestrian
detection application. Table 1 shows the array of operations and
precisions needed for this type of application. Even in a single task
needed.
to more devices and new applications continue to emerge for vision
computing. Because vision computing is so intensive in terms of
bandwidth and power, it’s not practical to run such algorithms on
optimized for high-volume pixel computations. g
Key Functions % of Processing Operations and Precisions
Pyramid generation 10 Fractional coordinate calculations (16-bit coordinates), pixel interpolations (8-bit values)
Gradient magnitude and orientation 25 Finite differences or Sobel (8-bit pixels), sum of squares (8-/16-bit gradients),
calculation square root (16-/32-bit values), divide (8-/160-bit values), Arctan (8-/16-bit values)
Histogram of gradients calculation 25 Magnitude projection on bins (16-bit values), weighted histograms (16-bit values)
Histogram normalization 5 L1 (sum) or L2 (sum of squares) (16-bit values), square root (32-bit values), divide (16-bit values)
Support vector machine classifier 35 Multiply accumulate (16-bit values)
FAMILY OF VISION DSPS
Cadence provides a family of configurable imaging and vision DSPs that balances processing
efficiency with flexibility, whilst supporting the complex algorithms used in imaging, video and
computer vision applications.
The Cadence Tensilica IVP DSPs, shown in Figure 1, are built on a rich SIMD/VLIW architecture
with a four-way instruction issue and up to 200 separate ALU operations per cycle. The DSPs
feature integrated DMA for data streaming and more than 2000 bits per cycle data memory
bandwidth. The family’s instruction set, memory system and data types are all optimized for
high-throughput, 8-, 16- and 32-bit pixel processing.
The processors are backed by a rich software environment with DSP C compilers featuring zero
assembly code and full OpenCV and OpenVX support with 800 optimized functions.
With these capabilities, the Tensilica IVP processor is an example of a DSP suited for enabling
vision computing intelligence. In a design, imaging and video algorithms can run on such a DSP,
releasing the multi-core host CPU to handle other essential tasks.
Table 1: Pedestrian detection application
Figure 1: Cadence
Tensilica imaging/vision
DSP supports vision
computing intelligence
applications

28 HMI
April 2016
uman-machine interface (HMI) has reached a
tipping point in recent years, with consumers
driving the need for modern innovations. They are
now setting the expectations for the relationship
with their devices, including interactions whilst in
the vehicle.
Due largely to increased demand for better interaction, HMI has
become increasingly sophisticated, with touchscreens and Internet-
connected devices at its centre. In the past, this evolution was
mostly driven by technological development and based on simpler
interactions, such as the turn of a knob or push of a button.
A clear example of this trend is in the automotive industry. In
the past, standard HMIs involved simple mechanical linkages,
such as pedals, shift levers and knobs. Today, the role of the
design engineer has shifted, due to consumer demand to provide
more interactive capabilities, all the way to the ability for drivers
to talk to their cars or take notes on a touchpad or the dashboard.
The same market factors are also spreading across other
industries, including home appliances, mobile devices and more.
developer’s role in designing the next generation HMIs. The
relationship with the device depends upon natural, intuitive ease
are now less tolerant of input methods that are only convenient
for the device to support, but rather want interface schemes that
are natural. The device must now deal with added complexities
WAYS IN WHICH DRIVERS WANT
MORE FROM THEIR HMIs
H
and new modes of interaction.
HMI today is all about more natural, intuitive and robust
input methods for consumers.
Touchscreen Displays
controlling most of our devices, including smartphones, tablets,
smart appliances and automotive infotainment systems. Touch
is so pervasive; systems without touch support are often viewed
as broken or non-functional.
To support increased consumer demand for touchscreen-
friendly HMI, engineers are now shifting from resistive touch
panels to projected capacitive touch panels that are far more
sensitive and often more granular in touch-location detection.
the touch screen so that a precise touch location is determined.
These displays provide a more intuitive experience, because
they have a quicker response time, and users can make inputs
with more accuracy.
Many capacitive screens today even boast multi-touch
(mutual capacitance mode) capabilities, which detect multiple
points on the screen simultaneously, for such functions
as zooming in and out. Older resistive touchscreens often
supported only a single touch, limiting more intuitive control.
Devices using capacitive touch, however, aren’t completely
free of its challenges. One of the most common is that many
capacitive displays appear to function perfectly when developed
in a controlled environment, such as a lab or manufacturing
plant, but fall short when exposed to the real world, such
with the display’s detection accuracy. Engineers need to take
environmental and electromagnetic interference into account
to provide a device that is highly reliable in detecting touch in
such varying conditions.
Another challenge with capacitive touch is that since the
touchscreens respond to the electrical properties of the
human body, they do not respond when the user is wearing
gloves. Some glove manufacturers have responded by making
touchscreen-friendly gloves. Many touchscreen suppliers are
now providing highly adaptive sensitivity controls that can
Consumers are setting the expectations for the relationship with their devices
THE DESIGN ENGINEER’S ROLE IS CONSTANTLY CHANGING IN AN EFFORT TO CREATE MORE INTUITIVE AND
BENEFICIAL INPUT METHODS FOR HUMAN-MACHINE INTERFACES. BY GARY BAUM, VP OF MYSCRIPT

HMI 29
Gesture Recognition
While it has been used for some time in the gaming world
to create a more immersive and interactive experience,
gesture recognition is emerging as a potential input method
for the most common control functions in the workplace
and everyday applications. Gesture recognition can be used
to make the same commands as users otherwise would
by tapping a touchscreen or clicking a remote control, by
simply making a gesture. Allowing the user to determine the
preferred interaction method is now becoming standard, and
multi-modal inputs are being adopted by many automotive
manufacturers.
Gesture recognition in electronic devices works by using
mathematical algorithms to interpret human gestures. There
are three common types of algorithm used for this purpose:
3D model-based algorithms, skeletal-based algorithms and
appearance-based models.
With 3D model-based algorithms, volumetric, skeletal or a
combination of the two types of models are used to determine
relative position and interaction. Skeletal-based algorithms
analyze a skeletal representation of the body to understand
the position and orientation of certain segments and the
accurate gesture reading. Appearance-based models are used for
as gesture templates.
A primary challenge engineers face with all forms of gesture
recognition is overcoming accuracy issues. For example, an
algorithm for one camera might not work with another, or image
and video noise can prevent gestures from being accurately
recognized.
There’s still a long road ahead for engineers to meet consumer
demands for accuracy and then make gesture-recognition
technology widely available.
Two-Way Communication
The Internet of things (IoT) by itself is expected to surpass
the PC, tablet and phone market by 2017. Business Insider
projects 50 billion devices will be interconnected, while other
devices. The reason is that connectivity will make devices more
between nodes. Consumers are rallying around the continued
growth of the IoT as they increasingly adopt connected devices
and expect their favorite brands to make their products more
interconnected.
As more industrial and consumer products integrate with
the IoT, the sensor’s role in the electromechanical network
has shifted. In the past, sensors were a discrete component
mostly working in isolation, but now they interact with
other components for two-way communication in smart
intuitive HMI for consumers, engineers face new challenges
in development and deployment. This is forcing a change in
the overall role of engineers and of communication across
engineering disciplines, as mechanical, electronic and software
engineers have to collaborate more than ever to understand
sensor input as part of a larger system.
market. Here, not only is sensor data aggregated and controlled,
but the quest for information is shifting processing capabilities
to the cloud. The emergence of 5G networks allows compute-
intensive tasks to be enhanced through cloud-based services.
With mechanical, electronic and software engineers teaming
up, IoT sensors are being built into consumer products,
mobile devices and more. For example, the next generation
of smartwatches has the potential to use the human body
as an antenna to detect what kind of object the wearer is
touching. The technology behind this development is called
EM-Sense and it uses the body’s natural electrical conductivity
to determine if a person is touching an electrical device and
automatically identifies the object as a kitchen appliance,
power tool or door handle with electronic locks, for example.
This gives the smartwatch a more accurate grasp of what the
user is doing compared to traditional mobile sensors such as
accelerometers or pulse monitors.
Text-To-Speech
While it was originally developed as a multimodal interaction
to read text out loud to the visually impaired, consumers have
also been the driving force behind continued technological
advancements in text-to-speech, where text is converted into
spoken voice output. This type of HMI can be used for reading-
based education, learning new languages, and in mobile apps,
such as reading a text whilst the user may be driving or engaged
elsewhere.
A text-to-speech system starts with a front end responsible
for converting symbols, numbers and abbreviations into their
HMI has become increasingly sophisticated, with touchscreens and
Internet-connected devices at its centre

HWR is a more intuitive input method than typing on a
keyboard, since it enables users to write on a touchscreen or
converts handwriting into meaningful information, understanding
and adapting to what the writing is creating, so the digital ink can
be easily processed, searched, shared and stored. Design engineers
can incorporate HWR and digital ink into apps, smart appliances,
cars and other devices, enabling users to write digitally as easily
and intuitively as with a pen and paper.
HWR is becoming common in education, as app developers
use it to create a more engaging educational experience.
Studies have also shown that handwriting helps students better
retain information when compared to typing on a keyboard,
making even more of a case for educational app developers to
incorporate this technology.
Writing is also gaining popularity as an input method for
information entry or control. In response to recent legislation
limiting smartphone use by drivers on the road, the automotive
industry has turned to handwriting recognition to make driving
less distracting and safer for consumers. It is now incorporated
into car dashboards in several newer models, so drivers can
directions, sending a text message or jotting down important
information.
Audi and Mercedes have developed a dashboard where
drivers can write letters on an ideally-situated touch surface
using handwriting and other gestures without ever taking their
eyes off the road. Letters are superimposed on one another
while HWR technology assembles the complete text entered.
Conversely, if drivers use touchscreen input for the same tasks,
they need to take their eyes off the road to find the correct
letters, numbers and characters. Inputs using this method
require additional planning, time and for the vehicle to be
stationary.
Making HWR and digital ink a reality has been a long road.
Since its inception, it has faced user experience challenges like
the stylus itself not recognizing messy handwriting or only
recognizing select languages. MyScript has developed technology
to recognize handwriting at the character level and across most
of the world’s languages, overcoming the original drawbacks
of HWR that prevented its widespread adoption. Today, text
recognition has expanded to include graphics, diagrams, math
equations, musical notes and more.
Handwriting conversion needs to work for most languages
This is a big task and changes the manner in which digital ink is
stored, from static stroke-based storage to interactive ink that is
aware of the digital context even as the ink is displayed.
The design engineer’s role is constantly changing in an
HMI. The examples outlined here are just a few ways HMI and
the engineering behind this technology has adapted to user
demands. g
30 HMI
April 2016
spelled-out counterparts. It also assigns phonetic transcriptions
to each word and divides the text into phrases, clauses and
sentences. The back end, called the synthesizer, then converts
the text into sound.
Text-to-speech has been around for decades and integrated
with computers since the 1950s, but Google is now at the
forefront of integrating this form of HMI into its apps and
application for its Android operating system that supports more
than a dozen languages. Currently, a few of Google’s text-to-
speech capabilities include reading Google Play Books out loud
and providing useful insight into the pronunciation of words via
Google Translate.
Google recently updated its text-to-speech capabilities to
include more male and female voice options, and in February
2016 updated its Docs app to allow voice-activated typing.
Some of the challenges still associated with text-to-
speech include converting numbers into words and correctly
For completely accurate text-to-speech, design engineers must
overcome hurdles such as these.
Handwriting Recognition (HWR)
Consumers are constantly on the go and more likely to have
their smartphones or tablets on hand than a pen and paper.
These devices are increasingly being used for quick personal
notes and business or educational tasks. These quick notes, such
as directions, grocery lists and more, are fundamental but not
enough. Also, important is the desire to use these devices in day-
Devices must now deal with added complexities and new modes of
interaction

32 ELECTRIC CARS
April 2016
ybrid electric vehicles are widely considered to be
green vehicles with fewer polluting emissions. They
offer advantages such as energy saving and clean
running, with research showing that they offer
energy savings of over 30% and produce 15% CO2
emissions than traditional vehicles.
In addition, traditional vehicle driving systems consist of
many power-train components that do not exist in hybrid
vehicles, making them simpler and more efficient. Hybrid
vehicle motors can be controlled directly, so it is possible
to design electronic control systems such as ABS (anti-lock
braking), ESP (vehicle stability), TCS (traction control) and
others. However, the electronic control system in electric
vehicles is implemented based on original engine models, since
drive motors are mounted directly on the drive axles.
Although this method reduces the design cycle and
lowers costs, it doesn’t completely exploit the advantages
H
Figure 2: Schematic of the RT3102 instrument’s internal components
of electric vehicles. Furthermore, some hybrid vehicles
use independent control of each of the four wheels,
which makes coordinated control between motors more
complicated. In this case, the measurement of a hybrid
electric vehicle’s stability is even more crucial and necessary
for vehicle safety.
Statistics by German car-maker Audi show that traffic
accidents at speeds of 80km/h and above are caused by
some 40% of the vehicles losing stability. Faster than
160km/h, almost all accidents are related to instability.
Better Control
Vehicle handling stability can be improved by controlling
the vehicle’s yaw motion. Sideslip angle and yaw rate
are two most important stability parameters. Sideslip
angle is the angle between the longitudinal axis of the
automobile and its direction. But, the sideslip angle can’t be
Figure 1: RT3102
navigation system
BY ZHIBIN MIAO AND HONGTIAN ZHANG FROM HARBIN ENGINEERING
UNIVERSITY IN CHINA
MEASURING HYBRID
ELECTRIC VEHICLE
STABILITY WITH THE RT3102
NAVIGATION SYSTEM

ELECTRIC CARS 33
Figure 3: Schematic of the strapdown navigator
measured directly, which is one of the biggest obstacles to the
development of vehicle stability control systems. Gyros measure
the yaw rate, but there is no suitable equipment to measure the
vehicle sideslip angle directly, which means estimating methods
must be used.
Usually, sideslip angle estimation is combined with the
yaw rate gyro and lateral acceleration sensing. Unfortunately,
these sensors also come with bias and noise. In addition, the
lateral accelerometer is not the best way to assess the lateral
acceleration and gravity component of avehicle acceleration,
since the sensor errors errors add up and affect the accuracy of
the stability control system.
The RT Series Of Navigation Systems
Using a GPS navigation system from the Oxford Technical
Solutions’s RT series does help in measuring the vehicle’s
sideslip angle. The RT series consists of several inertial and GPS
navigation instruments
that make precise
measurements of motion
in real time. Figure 1
shows the RT3102.
To obtain high-
precision measurements,
the RT uses
mathematical algorithms
developed for the
navigation systems
of fighter aircraft. An
inertial sensor block with
three accelerometers
and three gyros (angular rate sensors) is used to compute all
outputs. A WGS 84-modelled strapdown navigator algorithm
compensates for the Earth’s curvature, rotation and Coriolis
accelerations, whilst measurements from high-grade kinematic
GPS receivers update the position and velocity determined by
the inertial sensors. Figure 2 shows the schematic of the RT
instrument’s internal components.
This innovative approach gives the RT solution several
distinct advantages over systems that use GPS alone.
with very low, 3.5ms latency. All outputs remain available
continuously during GPS blackouts when, for example, the
vehicle drives under a bridge.
them. The position and velocity measurements the GPS
“
Statistics by German
car maker Audi show that trafﬁc
accidents at speeds of 80km/h
and above are due to some 40%
of vehicles losing stability. When
vehicle speed exceeds 160km/h,
almost all accidents are related to
instability
Figure 4: Schematic of single-lane testing
Figure 5: Measurement of hybrid electric vehicle with the RT3012

34 ELECTRIC CARS
April 2016
makes are smoothed to reduce high-frequency noise.
The RT instruments take many measurements GPS cannot,
for example acceleration, angular rate, heading, pitch and roll.
It takes inputs from a wheel-speed sensor to improve the drift
rate when no GPS is available.
The standard RT system processes data in real time, with
the results sent to the CAN bus via an RS232 serial port
over 10/100 Base-T Ethernet using a UDP broadcast. Each
output is time-stamped and referred to the GPS time;
a 1PPS timing signal can be used to give very accurate
The outputs of the system are derived directly from
the strapdown navigator, whose role is to convert
measurements from the accelerometers and angular rate
sensors to position. Velocity and orientation are also
tracked and sent out by the strapdown navigator. Figure 3
shows a basic overview of the strapdown navigator in the RT
3201 navigation system. Much detail has been left out and
only the key elements are shown here.
Testing Application
Single-lane experimental conditions are selected to
measure the vehicle sideslip angle, a method commonly
used in vehicle stability testing, and simulation of vehicle
overtaking and obstacle avoidance. The schematic is shown
in Figure 4. Here, B1
= 3.5m, S1
= 50m and S2
= 30m.
To demonstrate the advantages of this system, it was
used in a real-life stability test, with the RT3102 used in
hybrid electric vehicle mode, as shown in Figure 5, and
the double antennas set on top of the vehicle. The vehicle’s
sideslip angle measured by RT3102 is shown in Figure 6.
Kalman filters can be used to merge several
measurements for a better overall result. This is the case
with position and velocity in the RT module; the Kalman
filter is used to improve position measurements made
from two sources, inertial sensors and GPS. To illustrate
the advantages of using the Kalman filter, data with and
without it are compared in Figure 7. It can be seen that the
sideslip angle curve is smooth after applying the Kalman
filter algorithm.
In Figure 8, the vehicle sideslip angle, measured by the
3102 sensor, is compared with the sideslip angle measured
by the GPS/INS. Although the curves are similar, the
sideslip angle measured by 3102 is more precise. The testing
error is low.
Figure 6: Sideslip angle curve
Figure 7: Sideslip angle curve using Kalman ﬁlter
Figure 8:
Comparison of
the sideslip angle
curve

36 ITS
April 2016
apid urbanization, technological developments
also cause problems in our lives. For example,
dramatically, owing to greater vehicle ownership but
have been proposed to cope with this issue. With advances in
the computer and communication industries, studies are now
BY UMUT OZKAYA AND LEVENT SEYFI FROM SELCUK UNIVERSITY IN TURKEY
R
focusing on low-cost sensors and their real-time responses in
with many dynamic parameters, rendering some mathematical
modeling techniques inadequate. Fuzzy logic is known to be
an advanced approach for physical process management and,
loads. Fuzzy-logic models can predict outputs of problems with
nonlinear inputs; the number of rules in fuzzy logic control
varies accordingly to problem complexity.
Isolated Intersection Model
account the average vehicle density within a day, but not as it
dynamically changes throughout the day. For example, as shown
A NOVEL FUZZY LOGIC MODEL
FOR INTELLIGENT TRAFFIC
SYSTEMS
Figure 2: Trafﬁc intensity during a day
Figure 1: Intersection layout
Figure 3: Trafﬁc distribution cycle

ITS 37
Generally, this method aims to minimize vehicle delays, but it’s
of the day. For example, the daily commute is the most common
conventional system, every cycle has a constant amount of green
and red time, making the total number of cycles per day stable,
which never changes even though vehicle distribution in each
phase might.
some cycles may have longer
time in each phase can be
changed dynamically by the
fuzzy controller, changing
duration of the green light
in three of the four phases
is equal to the duration of red light times for the last phase.
are intertwined and they may change with the so called self-
subsequent phases, for example when a vehicle arrives at a phase.
All these criteria have to be considered before creating a
simulation model.
crossroads.
State Space Equations
A single-phase intersection must be modelled before designing a
Vehicle queue length is an important parameter in modelling a
where i = 0, 1, 2, 3… M and n = 0, 1, 2, 3… N-1 are sequentially
Qi
(n) and
qi
(n) are number of vehicles at nth time and in ith queue in the
nth time. di
(n)
in the ith queue at the nth time. S(n) is the phase state at logic
(S1
, S2
, S3
, S4
) = (0, 0, 0, 1) means that phase
four has a green light, the others red.
length of the discretized time.
Fuzzy Logic Control
to those of the human brain.
Fuzzy logic is a control method based on fuzzy set theory,
which translates real values into human linguistic variables
parameters.
certainty, multi parameters and non-linear behaviour.
Figure 4: Phase diagram
Figure 5: Fuzzy control structure
“
Typically,
transportation systems are very
complex to model, with many
dynamic parameters, rendering
some mathematical modeling
techniques inadequate

38 ITS
April 2016
to use fuzzy set theory. Here, system inputs initially undergo
are converted into linguistic variables, using membership
functions.
designed to avoid false results by the fuzzy control mechanism.
functions’ value ranges.
Our proposed fuzzy system has four inputs and three
memberships functions for each input, therefore the fuzzy block
n
is An n n
be added to increase system sensitivity but this will lead to
difficulties in the decision mechanism.
Figure 6: Example of input membership function
Figure 7: Example of membership function
Figure 9: Comparative flow chart
Figure 10: Fuel consumption
Figure 8: System flow chart for the old (conventional)
and new (proposed) traffic flow system

ITS 39
After the results are in the fuzzy rule base, they are
block.
Modelling Algorithm
extended, to reduce vehicle queues in all phases. Also,
state-space equations and fuzzy controls are set so as not to
disadvantage any phase in terms of time waiting.
We modeled the conventional and our newly-proposed
systems and compared the results.
new system, a fuzzy-logic controller is integrated with adaptive
of passing vehicles and exhaust emissions for all four roads at
an intersection are much better with the new system than the
evaluated with simulation with the isolated intersection
stress at red lights is reduced.
Finally, this is an eco-friendly system, helping intelligent
transportation systems.
TOTAL INDICATORS CONVENTIONAL FIXED TIME CONTROLLER FUZZY CONTROLLER DIFFERENCE
Number of Passing Vehicles 26440 34027 28.7%
Number of Cycles 684 890 30.1%
Red Light Time 215460s 162140s 24.7%
Table 1: Performance comparisons between conventional and fuzzy controller systems
Figure 11: NOx emissions Figure 12: HC emissions
Figure 13: CO emissions Figure 14: Particulate matter

40 MOTOR CONTROL
April 2016
he first electric motor was invented by William
Sturgeon in 1832, whereas the first commercially
successful electric motor was created in 1873.
Today, electric motors are found in a variety
of applications, including domestic, industrial,
mining, agriculture, transportation and others.
They can be used in elevators and lifts, kitchen machines,
wristwatches, mobile phones (to vibrate instead of ring),
scanners, printers, plotters, robots and others, as suggested
in Figure 1.
Motors’ flexibility and wide variety mean they can be
matched to almost any kind of application.
Motor Types
Depending on the power supply, motors can be divided into
two groups: AC (alternate current), run by high voltage, and
DC motors (direct current), run by rechargeable batteries
and thus suitable for portable applications.
There are two main types of DC motors: brush and
brushless. The brush DC motor uses a rotor with stationary
magnets, whereas the brushless ones use rotating permanent
magnets.
Then there are:
1. Stepper Motors, which are brushless, and rotate in
multiple steps. The stepper can move and hold at one
STOJCE DIMOV ILCEV FROM DURBAN UNIVERSITY OF TECHNOLOGY (DUT) IN SOUTH AFRICA GIVES A AN
OVERVIEW OF DIFFERENT TYPES OF MOTORS AND HOW BEST TO CONTROL THEM
T
of these steps without a feedback sensor. Stepper motors
are used to position the heads in floppy disk drives, and in
plotters, CD ROMs and scanners among others.
2. Servo Motors. These are used in servomechanisms, a device
relying on error sensing to improve machine performance.
In specific applications and high-torque requirements, these
motors can produce 8,000-70,000RPM.
Motor Control
Energy efficiency, mobility and security are important
challenges facing modern society. Motor-control solutions
can address all these needs, providing outstanding reliability,
excellent quality and leading-edge innovations. Thus, it’s
everyone’s goal to consistently improve motors’ computing
performance, switching frequency, figure of merit, accuracy,
quality and reliability, to name just a few of their many
technical parameters.
As new product generations are released, each device
becomes a benchmark in its own category. But the real beauty
lies in combining these individual devices and their strengths
to create different motor control systems able to set new
standards in energy efficiency, dynamic behaviour, robustness
and longevity.
It is also very important to harness the benefits of efficient
semiconductor solutions for electric motor control and drive
applications.
AC Motors
AC motors are much more prevalent than DC motors since they
offer several advantages. To match the choice of an AC motor
to the application, it is essential to know the different types.
The first type is the induction motor, also known as
asynchronous. Figure 2 shows a domestic low-power AC motor
(left) and an industrial high-power AC motor (right).
Figure 3 shows a simplified drawing of an induction motor
(left) and construction of its cage with a shorted rotor (right).
Such motors are used for kitchen aspirators, low-pressure
water pumps, air conditioners, hair dryers, mixers, vacuum
cleaners, fans and other domestic appliances where there’s
no need for high torque. They are self-starting, but because of
their relative low power and speed, control is not used.
AC motors are categorized as single-phase or three-phase AC
BASICS OF ELECTRIC MOTOR
CONTROL
Figure 1: The motor’s versatility

MOTOR CONTROL 41
motors, and further divided into low, medium (for example
the motor in Figure 3) and high power.
When a heavier load must be turned, a different type of
single-phase AC motor is used, with two stator windings
(main and auxilary) or starting windings, to provide a boost.
Auxilary windings provide an additional magnetic field,
shifted by 900
in relation to the main field.
After starting the motor, the auxiliary winding can be
disconnected, and a phase shift accomplished with either
a capacitor or an inductor. Depending on the motor’s
construction, the auxilary winding can remain connected
when the motor is in use.
The synchronous speed of the motor is given with the
following equation:
V = 120 • f/P
where f is the frequency applied to the motor
and P is the number of motor poles
An asynchronous motor can never reach
its theoretical synchronous speed, and
the difference between the real-life and
theoretical speed is called the ‘motor slip’.
Low-power motors can reach almost 50%
of synchronous speed, while moderate and
high power motors can reach only 2-5%.
Voltage-to-frequency ratio V/Hz is the additional
parameter that needs to be considered when designing with
motors.
Speed And Torque Control
Most basic DC drives and some AC drives can have their
motor speed (rotational speed) and torque controlled. The two
primary ways to control the speed of a single-phase AC motor
are to either change the frequency of the line voltage or the
voltage itself, thereby changing the motor’s rotational speed.
Increasing either frequency or voltage or both, increases
the RPM of the motor. A device known as Variable Frequency
Drive (VHD) controls frequency and voltage simultaneously
to keep a constant ratio of volts to hertz, so the motor sees a
constant current similar to full-speed conditions.
VFD’s don’t increase voltage, so as the
frequency increases the torque starts to
decrease. At some point, as the speed
increases there will not be enough torque to
drive the load, and the motor will slow down
even with increased frequency.
Most AC motor drives are fed from a three-
wire delivery without a neutral.
Line voltage is the potential difference
between two lines of different phases. This
means there are actually three line voltages
on a three-phase system: A-B, A-C and B-C. For a balanced
system, the three must be equal. However, phase voltage is
the potential difference between a line and neutral. A three-
phase system has three phase voltages as well: A-N, B-N and
C-N. For a balanced system, all three must also be equal.
An inverter changes DC voltage into an AC waveform,
and a PWM signal is output, filtering into a waveform with
a predetermined voltage voltage (controlling torque) and
frequency (controlling speed); see Figure 4 (left), which
shows the diagram of a single-phase asynchronous motor
with auxiliary winding (highlighted in green).
A capacitor connected in series with the auxiliary winding
“
The brush DC
motor uses an internal
power supply with stationary
magnets, whereas the
brushless ones use rotation
permanent magnets
Figure 2: Different types of AC motors
Figure 3: AC motor structure

42 MOTOR CONTROL
April 2016
helps achieve the additional phase shift; its value depends on
the motor’s rated power; its primary task is to start rotation.
To reduce its, the motor needs lower voltage on its main
winding, which will decrease its magnetic flux, increase slip
and decrease torque. However, to offset this, the auxiliary
winding still remains powered, at a level chopped by a triac
with a specific setting of its phase angle of conduction, which
has a direct influence on the magnetic flux.
Even though the waveform of the voltage on the primary
phase is not sinusoidal, the current becomes near sinusoidal
in shape because the motor acts as a low-pass filter.
The triac phase-control design is simpler, though. There
is a single triac in-line with the AC line, that chops the AC
waveform, causing the power to shut off during a portion of
the AC cycle.
Figure 4 (middle) shows the general schematic for a
triac-controlled drive. The motor shown is a permanent split
capacitor motor with two windings and a capacitor for phase
shifting.
Performance can be improved by moving to a three-wire
approach. Figure 4 (right) shows a fan driven by a three-wire
topology. The auxiliary winding is connected directly to the AC
line, maintaining full voltage as the RMS across the primary is
reduced by the triac.
Another method for speed regulation is by frequency. As
stated earlier, synchronous speed of rotation is given by speed,
however altering the frequency also changes rotational speed,
in a direct relationship.
Three-Phase AC Motor
Another commonly-used type of AC motor is the three-phase,
which uses the well-known Tesla rotating magnetic field, with
Figure 4: Single-phase asynchronous motor and speed regulation
Figure 5: Three-phase asynchronous motor and amplitudes
Figure 6: Two equivalent circuits IGBTs and motor speed regulator

MOTOR CONTROL 43
stator windings 120o
apart, as shown in Figure 5 (left). The
Y configuration for a reduced speed. This is used for starting
the motor to accelerate smoothly until it reaches the speed
defined by the reduced voltage. After reconnecting the
windings in the delta mode, the motor accelerates up to the
nominal speed rated at full hypothetical voltage.
Figure 5 (middle) shows a cross-section of a three-phase
AC motor, whilst Figure 5 (right) shows its amplitudes (the
black line relates to a single-phase motor).
Separate speed and torque regulations are now possible
using advanced electronics and microcontrollers. A new
generation of Insulated Gate Bipolar Transistors (IGBTs)
offers flexibility in designing the control logic, combining the
best characteristics of MOSFETs and bipolar transistors; see
Figure 6 (left).
The IGBT element is used in the output drive stages; it
needs low power in its gate circuit and is capable of handling
large ranges of voltage and current that in certain conditions
may require intensive cooling. A large heatsink and small
DC brushless fan will do the cooling functions in most
applications.
As stated earlier, the motor’s speed is directly proportional
to the applied frequency. For medium and small motors,
specific frequency and speed regulators are widely
available, as shown in Figure 6 (right).
DC Motors
The direction of the force and therefore the movement of
a wire can be determined using Fleming’s left-hand rule,
which explains the principle of DC motor function, as
shown in Figures 7 (left and middle).
A DC motor can have either a permanent magnet
(Figure 7 right) or field winding in the stator. Speed
control in these motors is managed by varying the current
through the rotor.
Wound Rotor Motors
A wound-rotor motor is a type of AC induction motor
where the rotor windings are connected via slip rings to
external resistances. In a wound motor the field winding is
connected in series with the rotor winding, which typically
has poor speed regulation.
A wound motor delivers increasing torque with
increased motor current but at the expense of speed. This
motor has a very high starting-torque because of zero back
electro-motive force (EMF) at zero speed; however, as the
Figure 7: Fleming’s left hand rule and DC motor
Figure 8: BLDC motor and permanent magnet rotor

44 MOTOR CONTROL
April 2016
speed builds up, the back-EMF causes a reduction in torque.
Increasing the load on the motor slows it down, which in turn
lowers back EMF and increases torque to accommodate the
load. Speed control is possible by varying the supply voltage.
Under no-load conditions the speed will accelerate to
dangerous levels with possible destruction of the motor,
which acceleration can be reversed by reversing the
connections on either the field or rotor windings, but not
both.
Applications range from inexpensive toys to automotive
applications, using both high and low power.
Shunt Wound Motor
A shunt wound motor also has only one power input to
the motor, but in this case the field winding is connected in
parallel with the rotor winding. Its speed can be controlled
to a limited extent without affecting the supply current by
“field weakening”. A rheostat in series with the field winding
reduces the field current. This in turn reduces the flux in the
air gap and, since the speed is inversely proportional to the
flux, the motor will speed up. However, the torque is directly
proportional to the flux in the air gap so the speed increase will
be accompanied by a reduction in torque.
This motor turns at almost constant speed if the voltage is
fixed, and can deliver increased torque by increasing the motor
current, without an appreciable reduction in speed. It can be
reversed by reversing the connections on either the field or
rotor windings. Regenerative braking is possible, so self-
excitation maintains the field when
the rotor current reverses. This is
useful for fixed-speed applications
such as automotive windscreen
wipers and fans.
Separately Excited Motor
A separately excited motor has
independent voltage supplies
to the field and rotor windings,
allowing more control over motor
performance through voltage
control of speed and torque.
Applications include rail and
automotive traction.
Brushless DC Motors (BLDC)
These days, BLDC motors are
rapidly gaining in popularity and
are used in various industries and
Figure 9: BLDC motor diagram
Table 1: DC motor types

MOTOR CONTROL 45
applications, including white goods, aerospace, automotive,
consumer, medical, industrial automation equipment and
instrumentation. As the name implies, BLDC motors do not
use brushes for commutation; instead, they are electronically
commutated, as shown in Figure 8 (left).
BLDC motors have many advantages over brushed DC
motors and induction motors, including better speed-
versus-torque characteristics, high dynamic response, high
efficiency, long operating life, noiseless operation, higher
speed ranges, and so on. In addition, the ratio of torque
delivered to the size of the motor is higher, making it useful
in applications where space and weight are critical factors. In
most constructions, the permanent magnet rotor is situated
outside the stator windings connected by the electronic
commutation; see Figure 8 (right).
One way of controlling BLDC motors is with Hall Effect
sensors attached below the magnetic rotor; see Figure 9. A
microcontroller counts impulses from the Hall sensors and
after comparing them with programmed values, regulates
the pulse widths for each stator winding, increasing or
decreasing the speed of the rotor.
Table 1 compares the characteristics of different types of
DC motors.
Stepper Motors
Stepper motor are used for accurate positioning. Unlike
other DC motors, stepper motors do not rotate linearly
but in steps (by one or many steps). The amount of rotor
movement per step depends on construction of the motor,
i.e. the number of stator windings per phase. For each
step it is necessary to apply the next impulse to another
winding.
There are two types of stepper motors (see Figure 10),
unipolar and bipolar. The difference two is the mode of
connection between winding and controller, as shown in
Figure 11.
There are many variations of stepper motor controllers,
from very simple through to very sophisticated.
Figure 10: The construction of a stepper motor
Figure 11: Unipolar and bipolar stepper motors

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