Motion control of underactuated flexible manipulator with moment-free joint and super-light link

This paper presents an underactuated manipulator (UAM) with super-light flexible links and demonstrates the validity of the optimal control trajectory on a 2-link UAM for two super-light arm cases. Utilizing a moment-free payload with a rotation axis and having the free joint device connected with small axes that reduce the generation of inertia moment, the arm achieves more lightness. Meanwhile, the manipulator possessing unactuated joints is categorized as a system subjected to nonholonomic constraints, hence its feedback control is difficult to realize. In this paper, the Fourier basis algorithm considering the flexibility of the super-light arm is employed to attain the optimal trajectory control of the manipulator. The effectiveness of the super-light mechanism and the optimal trajectory are verified through computer simulation and experimental tests; consequently, the adequateness of the control performance and the feasibility of the UAM with a super-light link are shown.