A joint-space command generator for Cartesian control of robotic manipulators

Many recently developed control schemes for robotic manipulators require as inputs the desired position, velocity, and in some cases, acceleration of each joint of the manipulator. However, it is most natural to specify the desired trajectory of the end effector in Cartesian coordinates. Thus it is desirable to have a command generator which has as input a desired Cartesian trajectory, and as output a vector of joint positions, velocities, and accelerations that correspond to the demanded trajectory. Such a command generator is presented in the form of a nonlinear feedback system that has the advantage of being related to a linear system. The linear system can be used to compute precise bounds on the performance of the nonlinear system. Simulation results for a nonspherical wrist manipulator are given