Servos

Combat robots use servomotors as actuators, positioning devices, and sometimes as drive motors. These servos are the same type used in remote-controlled devices such as model aircraft, boats and cars, as well as other hobbies. Most common radio-control receivers have connections for several servos, allowing them to be directly operated by the controls on the transmitter with very little setup.

These devices take a pulsed electrical signal (usually PWM, or Pulse-width modulation), and respond by moving a lever, slide, or shaft to a specific position. This motion is usually over a range of rotation such as 90° or 180°.

How to select a servo

In combat robotics, the limiting factors for servos are weight, voltage, torque, and cost.

A very durable servo with metal gears may be far too heavy for a small bot

Servos are usually powered by 5 volts from the receiver (instead of directly from battery voltage). The receiver might need a battery eliminator (BEC) module that generates enough power to run both the receiver and all the servo(s).

How to connect and use

Nearly all servos have a common type of 3-wire connector, although the wire colors vary:

• Ground wire – Black (or Brown)
• DC power wire – Red (or Orange)
• Signal wire – White (or Yellow)