A study on the movement capability of robot manipulators

A method is presented for characterizing the workspace and arranging the layout of a path for a robot manipulator from the viewpoint of movement speed performance. To measure the movement capability of a manipulator, the concept of speed radius is introduced. This index is defined on the basis of the relationship between the forces/torques exerted at joint actuators and the local geometric characteristics of the manipulator. Some properties of this measure are established. It is shown that the magnitude of the speed radius is not only constrained by the dynamics of the manipulator but also determined by the geometry of the path traced by the end-effector of the manipulator. To demonstrate the proposed scheme, a two-link planar manipulator is analyzed and its best posture is obtained by the developed measure for the movement speed capability. Applications of this scheme for path planning and workspace specification are presented. Simulations on several major issues are provided