The document describes a closed loop motor control system using an attitude and heading reference system (AHRS). The system uses an ADuC 7020 microcontroller along with an AHRS to control a motor based on roll data and rate from the AHRS every 5ms. It also includes a signal conditioning circuit and 3-bit parallel user interface to control the motor with 8 commands. The system provides steering and stabilization by keeping the line of sight of the motor the same regardless of rotation.

1. CLOSED LOOP MOTOR CONTROL USING
AHRS
BY
ESHAAN KUMAR
TEJAS S
SHILPA S
Under
the Guidance of
INTERNAL GUIDE EXTERNAL GUIDE
Mrs. Padmaja Vijaykumar Mr. R. Srinivasan
Department of ECE, AIeMS SC ‘F’, ADE, DRDO

2.  AHRS Gyros are used world wide in UAV’s
 Gyros are nothing but devices which measures
rate of rotation of an Object in Space.
 Traditional Gyros are Huge and Bulk and
Requires a large maintenance Cost as it is
purely Mechanical.
 AHRS can eventually replace these traditional
Gyros.
Typical Mechanical
Gyroscopes

3. Introduction of AHRS eventually lead to the
replacement of Traditional Gyros.
AHRS is an IMU used for measuring the position
of an object in Space.
AHRS Contains Accelerometer, Gyro meter and
magnetometers(17 bit)
Typical AHRS

4. AHRS is an 32 bit high performance processor
which measure parameter like Euler angles and
Euler rate.
AHRS Provides Digital data and o/p are based on type of Command
AHRS Configurations: (Serial port
configuration, baud rate, start bit ,stop bit, parity)
Principle axis of Rotation of an Aircraft

5.  Design an Closed Loop Motor Control system
which makes use of ADuC 7020 micro
controller along with AHRS for every ~5ms.
 Use the Roll data and Roll rate in order to
control the motor.
 Provide an appropriate Signal conditioning
circuit(hardware design) which is sufficient to
control the motor
 Also provide an user interface to change the
command using 3-bit parallel
port(8commands)

6. Function: The3DM-GX3™ will output a data record containing Euler
Angles and Angular Rates.
Command:
Byte1 0xCF
Function: The3DM-GX3™ will output a data record containing Euler
Anglesand AngularRates.
Response:
Byte1 0xCF
Bytes2-5 Roll (IEEE-754Floating Point)
Bytes6-9 Pitch (IEEE-754Floating Point)
Bytes10-13 Yaw (IEEE-754Floating Point)
Bytes14-17 AngRateX (IEEE-754Floating Point)
Bytes18-21 AngRateY (IEEE-754Floating Point)
Bytes22-25 AngRateZ (IEEE-754Floating Point)
Bytes26-29 Timer
Bytes30-31 Checksum

7. µC is required because
1. One Serial RS 232 interface - For AHRS
2. 3 – bit parallel port interface to set the roll
command
3. DAC

13. Equation
0 0 1 1 1 1 1 1 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
S E M
1 bit 8 bits 23 bits

14. Example :
0 01111110
o S = 0
Number is Positive
o E = 01111110 b = 126 d
e = E -127 = -1
o M = .10000000000000000000000 = 0.5 d
10000000000000000000000
N = 0.75 d

15. 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 00 0 1 1 1 1 1 1 0
S E M
a[3] a[2] a[1] a[0]
To Find S
To Find E

16. 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 00 0 1 1 1 1 1 1 0
S E M
a[3] a[2] a[1] a[0]
To Find N
To Find M

18. fb from AHRS (ROLL angle) Read Cmd selected as on (from parallel port)

24. Picture shows the AHRS o/p as seen on a DAC when it is
manually rotated from +/- 180 degrees.

25. Picture shows the update value from AHRS in every 10m sec

26. The roll output of the AHRS on DAC

27. The output of the Roll rate on DAC in the closed loop when
seen on a oscilloscope.

28. P(1.4) P(1.3) P(1.2) Angle(in degree) Command
0 0 0 157 0x6FF
0 0 1 90 0x3FF
0 1 0 45 0x1FF
0 1 1 0 0
1 0 0 -45 0xFFFFFE03
1 0 1 -90 0xFFFFFBFF
1 1 0 -157 0xFFFFF900
1 1 1 67 0x2FF
List of Commands

29. The roll output of the AHRS on DAC for a step command of +157 deg

30. The roll output of the AHRS on DAC for a step command of -45 deg

36.  AHRS is proved to be a useful element to be
used in UAVs.
 Designed system gives the update value from
AHRS for every ~5ms.
 System designed provides Steering and
Stabilization mechanism.

37.  A successful attempt was made to design a
closed loop control system using available
motor with AHRS.
 This project has also demonstrated its
performance in using in any steering and
stabilization system in space.
 The line of sight of motor remains the same
irrespective of the rotating motor .