Trajectory tracking control of a 2-DOF manipulator using computed torque control combined with an implicit lyapunov function method

Abstract

A combined control method based on computed torque control and an implicit Lyapunov function method for trajectory tracking controlling of a 2-DOF manipulator was investigated. The manipulator works under condition of random base vibration and payload uncertainty. Base vibration acts on the manipulator in two directions: in vertical direction and in pitching direction. The computed torque control employed here aims to linearize the strongly nonlinear coupling manipulator system, and also to decouple it. Implicit Lyapunov function control method is one type of continuous feedback control. Its control gains are differentiable function of system error variables, and as the system error variables tend to zero, control gains will turn to infinite. Even so, this method can guarantee the control forces bounded in norm through the control process. The combined method is analyzed based on analytical models of manipulator system, which are established via second kind Lagrange equation. Specially, the analytical models are established according to base vibration in two directions. Numerical simulation results show that the combined control method has strong robustness against random base vibration in both direction and payload uncertainty. Besides, under all conditions considered in this paper, the method can always have fast convergence and high tracking accuracy.