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1. Rushikesh Kale
ME3423
Robotic Drives and Control

2. Actuators are devices used to produce action or motion.
Input(mainly electrical signal , air, fluids)
Electrical signal can be low power or high power.
Actuators output can be position or rate i. e.
linear displacement or velocity.
Actuation can be from few microns to few meters

3. A
Power
amplification
& modulation
Energy
conversion
Control
signal
Actuator
Output
Unmodulate
Energy source

4. Linear actuator: solenoid, Hydraulic/Pneumatic.
Rotary actuator: motor, Hydraulic/Pneumatic.

5. A solenoid is a coil wound into a tightly packed helix.
In physics, the term solenoid refers to a long, thin loop
of wire, and wrapped around a metallic core.
which produces a magnetic field when an electric current
is passed through it.

6. Pneumatic valve.
Car door openers.
Hydraulic cylinder
Single pressure line

7. Hydraulic systems are used to control & transmit power.
A pump driven by prime mover (electric motor) creates flow of fluid
Linear actuator (hydraulic cylinder)-
Provides motion in straight line.
Linear displacement depends on stroke length.
Usually referred to as cylinders, rams (single acting cylinders)
or jacks.
Rotary actuators (Hydraulic motors)-
Produces continuous rotational motion.
Pump shaft is rotated to generate flow.
A motor shaft is caused to rotate by fluid being forced into the
driving chambers.

8. Semi rotary actuators-
Produces non-continuous rotational motion.
Limited to less than one revolution (<360°).
Used to produce oscillatory motions in mechanisms.
Hydraulic jack.
Hydraulic brake.
Hydraulic ram.
Used as sensor.
Close loop velocity controlling.
Highly precise positioning for heavy loads.

9. It convert energy formed by compressed air at high pressure
into ether linear or rotary motion.
Quickly respond in operation.
Pneumatic actuator

10. HYDRAULIC & PNEUMATIC ACTUATORS:
CYLINDERS
10
Single acting:
work can be done only in one direction
Piston
Double acting piston:
Piston rod on both sides
Plunger
Work is done in both directions
Telescopic
Telescopic
Tandem

11. Non cushioned cylinders
are suitable for full stroke
working at slow speed.
Higher speeds with
external cushions.

12. ROTARY HYDRAULIC ACTUATORS
12
Vane rotary actuator:
 Limited angle in both directions.
 Maximum angle always smaller than 360°
 The same torque in both directions.
Piston rotary actuator:
 With rack and gear coupling.
 Here maximum angle may be larger than 360°
Limited angle rotary
actuator
Limited angle rotary
actuator
Parallel
piston
rotary
actuator

13. Mechanical linear actuators typically
operate by conversion of rotary
motion into linear motion.
Screw
Wheel and axle
Cam

14. Electrically actuated system are very widely used in control system
There are three types of motor used in control system
D.C. motor
A.C. motor
Stepper motor
Every motor works on the principle that when a current-carrying
conductor is placed in a magnetic field, it experiences a mechanical
force.
Working Principle of motor

15. A.C. motor
Stepper motor
Permanent magnet type
Variable reluctance type
Hybrid type
A stepper motor is an electromechanical device which converts electrical
pulses into discrete mechanical movements.

16. Pierre and Jacques Curie discovered the piezoelectric effect in 1880.
The application of an electric field to a piezoelectric crystal leads to a
physical deformation of the crystal.
Piezoelectric materials are: Quartz, Ceramics, PZT(lead zirconate
titanade).
Advantages
short response time.
An ability to create high forces.
A high efficiency and a high mechanical durability.
Disadvantage
Have small strains. (0.1-.2%)
High supply voltage needed.(60-1000V)
Large hysteresis.(actuator doesn’t go back to exactly
where it started).

17.  A piezo ceramic crystal is coated with silver on both sides.
 Glued to a brass, nickel alloy, or stainless steel disk.
Brass:
Commercial & industrial use.(not subjected to environment )
Nickel alloy:
Use where it subjected to environment.
Stainless steel:
Uses where it subjected to solvent, corrosive chemical,
Underwater .
Medical fields.

18. Piezoelectric Stack Actuators
Produce linear motion.