LFT gain scheduled H-infinity control for a robotic manipulator
机器人LFT变增益∞控制

A new approach to design an LFT gain scheduled H-infinity controller guaranteeing good dynamic performance in the whole operation range for a planar two-joint direct drive robotic manipulator was presented. The robot system was translated into an LPV (linear parameter varying) model taking the cosine of joint between two joints as the varying parameter. This LPV model was expressed as LFT structure about the varying parameter. Using the measured value of the varying parameter, the LPV H-infinity controller was designed with the same LFT structure. The controller design was equivalent to the robust LTI controller design taking the varying parameter as uncertainty term. The solvable LMIs (linear matrix inequalities) condition of the designed controller was given and the solved method to obtain the controller was induced. The designed controller not only overcomes the limitation of the conventional gain scheduled controller, but also reduces the conservation via the measured varying parameter. Experiment results prove the effectiveness and advancement of the designed controller.