Design and control of minimum-phase flexible arms with torque transmission mechanisms

A flexible arm with a special transmission mechanism is analyzed, and a method for integrated design of the arm structure and controller is presented. Control of flexible arms is a difficult problem because of the complicated dynamic coupled with the nonminimum-phase nature which is due to the noncollocated construction of sensor and actuator. The transmission mechanism developed relocates the torque-actuation point on the arm and modifies the flexible arm to a minimum-phase system. The resulting flexible arm is analyzed in terms of poles and zeros that are changed by relocating the torque-actuation point. A simple prototype arm is designed and compared with a nonminimum-phase arm. The effectiveness of the special transmission is discussed with regard to control performance, and an integrated structure/control design methodology is proposed