Casting motion controller for multilinked manipulator utilizing output zeroing

This paper describes fly-casting motion control for a multilinked manipulator named `fly-casting manipulator´, which consists of a casting rod, a fly line and a sinker. This manipulator simulates fly-fishing rod and has flexible potential. Flexible structure such as fly-fishing rod has advantages of accumulating energy because of its flexibility. Fly-casting motion has three phases, back-casting motion, collision and forward casting motion. Back-casting motion and forward-casting motion are energy accumulating phases and collision is energy losing phase. Additionally, the number of control inputs is less than the degree of freedom of the fly-casting manipulator. Thus, it is not possible to control all the states. Since this property makes it difficult to handle the casting rod, control problem of fly-casting motion is interesting as a point of view of control theory. Fly-casting manipulator is modeled as a multilinked underactuated manipulator. Only base joint is active joint, while the others are passive and constrained by torsion springs. The springs generate bending force which makes manipulator control easier. The proposed controller for casting motion is based on an input-output linearization and an output zeroing control to constrain the sinker on the desired path. Simulation results show the effectiveness of the proposed controller.