1. Tony Yi 5/2/2015 CENG4480 TUTORIAL 3

2. ABOUT ME I am “the other” tutor of CENG4480 You can find me at Rm116 in SHB Email : wyyi@cse.cuhk.edu.hk

3. THE FULL PICTURE Environment Sensor Input Control System Actuator Output We focus on this part.

4. ACTUATOR To convert the digital signals into mechanic motion Motor (mainly), heater, buzzer, LED, LCD Internal Signal Actuator Feedback

5. ACTUATOR Introduce Pulse-Width-Modulation (PWM) Focus on servo motor Internal Signal Actuator Feedback

6. PULSE WIDTH MODULATION (PWM) Pulse-width-modulation (PWM) is a fancy term for describing a type of digital signal Changing ‘HIGH’ time of the output signal HIGH LOW “HIGH” time

7. PULSE WIDTH MODULATION (PWM) Duty cycle On Time Off Time

8. PULSE WIDTH MODULATION (PWM) Example https://www.youtube.com/watch?v=X1ZmNHg0G30

9. SERVO MOTOR A servomotor is a rotary actuator that allows for precise control of angular position, velocity and acceleration.

10. SERVO MOTOR Small device that has an output shaft Angular position of that shaft controlled by the input signal (typically PWM) Shaft Body Input Signal

11. SERVO MOTOR A servo motor itself is a close loop control system. Gear Control Circuit Position Sensor (connected to shaft) DC Motor

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