Arm-type robots or robot manipulators are a very common and familiar type of robot. We are used to seeing pictures or video of them at work in factories doing jobs such as assembly, welding and handling tasks, or even in operating rooms doing surgery. The first robot manipulators started work over 50 years ago and have been enormously successful in practice — many millions of robot manipulators are working in the world today. Many products we buy have been assembled, packed or handled by a robot.
Unlike the mobile robots we discussed in the previous part, robot manipulators do not move through the world. They have a static base and therefore operate within a limited workspace. Many different types of robot manipulator have been created, but the most common is the 6DOF arm-type of robot comprising a series of rigid-links and actuated joints. This serial-link manipulator is the principle topic of this chapter.