16. A servomotor is a rotary actuator or linear actuator that allows for precise control
of angular or linear position, velocity and acceleration. It consists of a suitable
motor coupled to a sensor for position feedback. It also requires a relatively
sophisticated controller, often a dedicated module designed specifically for use
with servomotors.
Servomotors are not a specific class of motor, although the term servomotor is
often used to refer to a motor suitable for use in a closed-loop control system.
Servomotors are used in applications such as robotics, CNC
machinery or automated manufacturing.
DC Servo motor
AC Servo motor
30. A stepper motor has a step angle of 15°, How many pulses are required
for the motor to rotate through one complete revolutions?
1 pulse to turn 15°
Number of pulse (n) = 3600/ 15°
n = 24 pulse/rev
What pulse frequency is required for the motor to rotate at a speed of 100
rev/min?
𝑓𝑝= 24𝑝𝑢𝑙𝑠𝑒/𝑟ev x 100 𝑟𝑒/𝑚𝑖𝑛 = 2400 𝑝𝑢𝑙𝑠𝑒/min
𝑓𝑝= 2400 𝑝𝑢𝑙𝑠𝑒/min x (1/ 60 min/sec )
= 40 Hz
31.
32. Stepper motor Characteristics Slew Range: The region
between the pull-in and pull-
out torque curves.
A motor may operate in
this range, but cannot start,
stop, or reverse without
ramping. Stator: The stationary
part of the motor. Step: The
movement of the rotor from
one energized position to the
next.
Step Angle: The nominal
angle through which the
shaft of a stepper motor
turns between adjacent
step positions. It is
dependent upon the motor
and driver sequence (full,
half, or Microstepping).
34. What are Brushless DC Motors Used For?
Brushless DC motors typically have an efficiency of 85-90%, while brushed motors are
usually only 75-80% efficient. Brushes eventually wear out, sometimes causing
dangerous sparking, limiting the lifespan of a brushed motor. Brushless DC motors are
quiet, lighter and have much longer lifespans. Because computers control the
electrical current, brushless DC motors can achieve much more precise motion
control.
Because of all these advantages, brushless DC motors are often used in modern
devices where low noise and low heat are required, especially in devices that run
continuously. This may include washing machines, air conditioners and other
consumer electronics. They may even be the main power source for service robots,
which will require very careful control of force for safety reasons.
Brushless DC motors provide several distinct advantages over other types of electric
motors, which is why they’ve made their way into so many household items and may
be a major factor in the growth of service robots inside and outside of the industrial
sector.
