This document discusses various types of actuators used in robotic drives and control systems. It describes linear actuators like solenoids and hydraulic/pneumatic cylinders, as well as rotary actuators like motors and semi-rotary hydraulic actuators. It also covers mechanical linear actuators, electrically actuated systems like DC, AC, and stepper motors, and piezoelectric actuators. Piezoelectric actuators offer advantages like short response time and ability to create high forces but have small strains and require high voltages.

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.