Active vibration control of a flexible base manipulator

A rigid (micro) robot mounted serially to the tip of a long, flexible (macro) robot is often used to increase reach capability, but flexibility in the macromanipulator can make it susceptible to vibration. A rigid manipulator attached to a flexible but unactuated base was used to study a scheme to achieve macromanipulator positioning combined with vibration damping of the base. Inertial interaction forces and torques acting at the base of the rigid robot were studied to determine how to use them to damp the base vibration.; The ability of the rigid robot to create inertial interactions varies throughout the workspace. There are also “inertial singularity” configurations where the robot loses its ability to create interactions in one or more degrees of freedom. A performance index was developed to quantify this variation in performance and can be used to ensure the robot operates in joint space configurations favorable for inertial damping. When the performance index is used along with appropriate vibration control feedback gains, the inertia effects, or those directly due to accelerating the rigid robot links, have the greatest influence on the interactions. By commanding the link accelerations out of phase with the base vibration, energy will be removed from the system. This signal is then added to the rigid robot position control signal. Simulated and measured interaction forces and torques generated at the base of a rigid robot are compared to verify conclusions drawn about the controllable interactions. In addition, simulated and experimental results demonstrate the combined position control and vibration damping ability of the scheme.