Robotic Arms, are a particular type of robotic actuator. The arm is actually constructed with several servos. If the arm is described as a 5-axis arm, then there are normally five servos, and a six axis arm has six servos, and so on. Normally the arm has a gripper, and any of... wrist, elbow, shoulder and rotator.
So controlling the arm requires the co-ordinated manipulation of all the servos. The actual logic of which servos to move (and by how much) will be performed by the controller... the actual commands to move the servos may be done by the controller itself, or by a SSC (Serial Servo Controller), driven by the controller.
