ABSTRACT
This chapter presents a brief description of electrical machines used in robots. The term “electrical machine” defines devices that convert mechanical energy to electrical energy or vice versa. In this chapter, we will cover the basic concepts and describe the relevant issues required to choose a suitable system for powering robots. Since the requirements of motion differ from robot to robot, it is imperative to know the particular requirements of a robot before choosing a drive system. For example, a robot designed to work in a car-manufacturing factory may need the same speed requirements in all the joints, but may need different requirements of torque depending on the joint. (Torque is defined as the rotational force that rotates a shaft and it is usually measured in newton-meters. In comparison, force pushes along a straight line and is measured in newtons.) The actuators at the robot end effector may need only relatively less torque when compared to the base motion joints. On the other hand, a humanoid robot may need high torque in its “roll” joints (joints that sway the robot sideways), however, rotating with less speed. The knee joints may have exactly opposite requirements.
