Advanced motion control in robotics

An analysis of robustness and a design principle for advanced motion control in robotics are presented. The performance of motion control in a single joint is evaluated according to its robustness. A robust control technique for robotic motion is developed. For quick recovery, the feedforward loop compensates the interactive torque, which the observer identifies with a certain time delay. If the time delay of the observer is negligibly small, an acceleration controller is realized. In the observer-based system, it is possible to show that this delay also determines the sensitivity function, which is the index of how the controller reduces the effect of not only the interactive torque but also the parameter variations. In a multi-degree-of-freedom motion system, the total mechanical system is described by the dynamical equations and the kinematic equations. If a drive system in each joint is an observer-based acceleration controller, only the kinematics need be taken into account in the motion control. Several examples in robotics of motion systems applied to position control and force control systems are discussed