7: Robot arm kinematics

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 serial-link 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.

This chapter covers:

  • describing the link and joint structure of a robot — Denavit-Hartenberg notation
  • determining the pose of the end effector given joint coordinates — forward kinematics
  • determining the joint coordinates given the pose of the end effector — inverse kinematics
  • generating smooth paths for the end-effector
  • motion through a singularity
  • joint angle offsets
  • modified Denavit-Hartenberg notation
  • Examples
    • drawing on a surface
    • a simple walking robot