1. Microprocessor and Microcontroller Based Systems Instructor: Eng.Moayed N. EL Mobaied The Islamic University of Gaza Faculty of Engineering Electrical Engineering Department بسم الله الرحمن الرحيم EELE 4315 — Fall 2010 Lecture 15

2. In this lecture we will present: Actuators types Control method for:  DC motor  AC motor  Stepper motor  Servos motor Actuators are used in order to produce mechanical movement in robots. Actuators for Robots

3. Actuator Types

4. Electrical Actuator

5. DC Motor

6. AC Motor

8. Stepper Motor

10. Servos Motor

11. Hydraulic Actuators

13. Pneumatic Actuators

15. Other Actuators

16. Controller H-bridge PWM control DC motor control

18. DC motors only have two leads. The direction it spins is determined by which terminal has power applied and which is connected to ground. An H-bridge consists of four switches (in our case BJTs) and depending on which two are closed, allow the motor to operate in either direction We chose to use an L298 chip from STMicroelectronics because it has two H-bridges in one package. H-Bridge

19. DC motor control PWM control A pulse-width modulated signal is a rectangular waveform with a varying duty cycle. A longer duty cycle means the voltage is on for longer and the average voltage applied to the motor is higher and vice versa. Will be implemented using the PWM generator on our microcontroller.

20. Pulse-Width Modulation

21. Stepper Motor (uni-polar)

22. Stepper Motor 0001001001001000 Stepping Sequences for Single Coil Excitation Only one coil is active at a given instant of time

23. Stepper Motor Single Coil Excitation

24. Stepper Motor (Single Coil Excitation)

25. 1001001101101100 Stepping Sequences for Double Coil Excitation Two coils active at any given instant of time Stepper Motor (Double Coil Excitation)

27. Stepper Motor (Driver circuit)

29. Stepper Motor (sequence)

31. Servos motor

32. lDo not confuse “servos” with “servo motors”

33. Servos Motor

34. Motors and Encoders

35. Feedback measurement “optical encoder” Relative position - direction - resolution grating light emitter light sensor decode circuitry

36. Ideal mask/diffuser grating light emitter light sensor decode circuitry Real A diffuser tends to smooth these signals Optical Encoders

37. Relative position - direction - resolution grating light emitter light sensor decode circuitry Optical Encoders

38. Relative position - direction - resolution grating light emitter light sensor decode circuitry A B A B A lags B Optical Encoders

39. Relative position - direction - resolution grating light emitter light sensor decode circuitry A B A leads B Phase lag between A and B is 90 degree Optical Encoders

40. Design # 1 ( Stepper motor) Design problems Design controller for stepper motor  Switch for on/off  Switch for right/left rotation with single coil excitation method.  Switch for right/left rotation with double coil excitation method.  Switch for speed (1,2) selection.