Robot Arm Kinematics

Abstract

Kinematics is the branch of mechanics that studies the motion of a body, or a system of bodies, without consideration given to its mass or the forces acting on it. A seriallink manipulator comprises a chain of mechanical links and joints. Each joint can move its outward neighbouring link with respect to its inward neighbour. One end of the chain, the base, is generally fixed and the other end is free to move in space and holds the tool or end-effector.

Figure 7.1 shows two classical robots that are the precursor to all arm-type robots today. Each robot has six joints and clearly the pose of the end-effector will be a complex function of the state of each joint. Section 7.1 describes a notation for describing the link and joint structure of a robot and Sect. 7.2 discusses how to compute the pose of the endeffector. Section 7.3 discusses the inverse problem, how to compute the position of each joint given the end-effector pose. Section 7.4 describes methods for generating smooth paths for the end-effector. The remainder of the chapter covers advanced topics and two complex applications: writing on a plane surface and a four-legged walking robot.