Servo motors, or servomechanism motors, are used to position robotic appendages such as arms, grippers, and sensor mounts or to create other movements where position is the important factor. Unlike the wheel motors (DC motors), where speed is the factor, these motors are used where (to some level of accuracy) a position of 90 degrees or 110 degrees might be required. Code can be used to control these precise positioning movements or a sequence of them. The following photo shows a small selection of servo motors:
These come in many sizes, from the very small at around 20-30 mm (shown in my photo) to those large enough to move heavy machinery. The next photo shows some of these servos in use for a small variety of my robots:
SpiderBot uses 18 servo motors to precisely position...