M7 Mixed Signal Analysis - Actuators.pptx

For the course Mixed Signals
Topic Actuators Definition Types

1. Module 7 Actuators

2. What is an actuator? 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. Actuator functional diagram A Power amplification & modulation Energy conversion Control signal Actuator Output Unmodulate Energy source

4. Types of actuators: Hydraulic actuator. Pneumatic actuator. Mechanical actuator. Electrical actuator Linear actuator: solenoid, Hydraulic/Pneumatic. Rotary actuator: motor, Hydraulic/Pneumatic.

5. Solenoid: 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. Application Pneumatic valve. Car door openers. Solenoids controlled valves Hydraulic cylinder Single pressure line

7. Hydraulic actuator: 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. Types of hydraulic actuator

8. Semi rotary actuators- Produces non-continuous rotational motion. Limited to less than one revolution (<360°). Used to produce oscillatory motions in mechanisms. Applications 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 CONSTRUCTIONAL FEATURES OF CYLINDER

10. Hydraulic & pneumatic actuators: cylinders 10 Single acting: work can be done only in one direction Piston Double acting piston: Piston rod on both side s 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. Double acting cylinder with & without cushioning

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 actuator Mechanical linear actuators typically operate by conversion of rotary motion into linear motion. Types of mechanics Screw Wheel and axle Cam

14. Electrical actuator 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. Piezoelectric actuators 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. Configuration 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. Types of piezoelectric actuators Piezoelectric Stack Actuators Produce linear motion. Linear motor Piezoelectric bender actuator

19. Other type of actuator Heaters - used with temperature sensors And temperature controller to control the temperature in automated moulding Equipment and in soldering operation . Lights - Lights are used on almost all machines to indicate the machine state and provide feedback to the operator. LED LCD’s Gas plasma display CRT Sirens/Horns - Sirens or horns can be useful for unattended or dangerous machines to make conditions well known.

20. Activity Cite 5 examples in which the actuators maybe applied in real life