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SERVO MOTORS. Tech Topic By Ryan Bidlack. Background. A servo motor is composed of a DC, AC, or an AC induction motor and a feedback control. Servo Motor Control. DC Servo motors are controlled with a PWM signal (square wave)
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SERVO MOTORS Tech Topic By Ryan Bidlack
Background • A servo motor is composed of a DC, AC, or an AC induction motor and a feedback control.
Servo Motor Control • DC Servo motors are controlled with a PWM signal (square wave) • In order to accurately hold a position servos need a pulse every 20ms • The duration of the pulse decides how far the servo rotates.
Most applicable for our uses. Cheap ($5-$40) Usually consist of a geared DC motor Need to have mechanical stop removed for 360 degree rotation. RC Servos
RC Servo Typical DC Servo Motor DC motor Housing Feedback controller Gears
Servo vs. Stepper motor • Servo Motors provide: • Higher rotational torque • Higher max RPM • Positive Feedback Control • Stepper Motors provide: • Higher holding torque • More precise movement
References • Seattle Robotics Society http://www.seattlerobotics.org/guide/servos.html • Electric Motors Reference Center http://www.electricmotors.machinedesign.com • WOODWEB knowledge base http://www.woodweb.com/knowledge_base/ • A1 Servo Motor Repair http://www.servorepair.com/