The PPR planar manipulator

Abstract

In the last few years, we have witnessed great interest in the control of robot manipulators with elastic joints and links. In this chapter, we will consider a planar elastic manipulator with three actuated joints, wherein the third actuated joint is coupled to the end effector through an elastic joint. This system is in fact a planar robot with two prismatic and one revolute (PPR) joints, moving on a horizontal plane so that no gravitational forces appear in the system. The three PPR joints are actuated, while the elastic degree of freedom appearing in the system is not actuated. Therefore, the system is underactuated, since it has four degrees of freedom with only three control inputs. This example is a type of robot manipulators that exhibit features of joint elasticity and kinematic redundancy [88].