1. SERVO MOTORS Tech Topic By Ryan Bidlack

2. Background A servo motor is composed of a DC, AC, or an AC induction motor and a feedback control. A servo motor is composed of a DC, AC, or an AC induction motor and a feedback control.

3. Servo Motor Control DC Servo motors are controlled with a PWM signal (square wave) DC Servo motors are controlled with a PWM signal (square wave) In order to accurately hold a position servos need a pulse every 20ms In order to accurately hold a position servos need a pulse every 20ms The duration of the pulse decides how far the servo rotates. The duration of the pulse decides how far the servo rotates.

4. Servo Motor Control

5. RC Servos Most applicable for our uses. Most applicable for our uses. Cheap ($5-$40) Cheap ($5-$40) Usually consist of a geared DC motor Usually consist of a geared DC motor Need to have mechanical stop removed for 360 degree rotation. Need to have mechanical stop removed for 360 degree rotation.

6. RC Servo Typical DC Servo Motor DC motor Gears Feedback controller Housing

7. Servo vs. Stepper motor Servo Motors provide: Servo Motors provide: 1. Higher rotational torque 2. Higher max RPM 3. Positive Feedback Control Stepper Motors provide: Stepper Motors provide: 1. Higher holding torque 2. More precise movement

8. References Seattle Robotics Society Seattle Robotics Society http://www.seattlerobotics.org/guide/servos.html Electric Motors Reference Center Electric Motors Reference Center http://www.electricmotors.machinedesign.com WOODWEB knowledge base WOODWEB knowledge base http://www.woodweb.com/knowledge_base/ A1 Servo Motor Repair A1 Servo Motor Repair http://www.servorepair.com/

9. Questions ?