A servocompensator approach to the control of flexible space robotic manipulators with application to teleoperation

A control concept applicable to the teleoperation of multilink, structurally flexible manipulators, based on commanded velocity of the end-effector, is presented. A velocity-tracking controller is used to effect the desired motion of the manipulator. The controller seeks to minimize the velocity tracking error at the cost of allowing the links to flex. This controller is designed by precomputing gains based on a set of dynamics equations, obtained by linearizing over a space of predetermined geometrical configurations and casting them into state-space form. Appropriate real-time controller gains are determined by interpolating between a subset of those precomputed gains, corresponding to geometrical configurations, in the neighborhood of the desired configuration. The system is augmented with a second-order integrator (for torque smoothing) and further augmented by a servocompensator whose input is the error between the actual end-effector velocity and the reference (command) velocity. Although principally motivated by teleoperation, the controller can also be used in an autonomous mode, which is the focus of this paper