This paper examines the use of noncollocated passivity-based control on a 5-bar-linkage manipulator with the last link flexible. By defining appropriate output variables such that the resulting transfer functions are passive, very simple low-order controllers can be designed. Previous work on this robot allowed only horizontal vibrations in the last link to take place, thus simplifying the problem. In this paper, the last link can have transverse vibrations in two dimensions. Gravitational effects must also be considered. Experimental and simulation results are shown which demonstrate the feasibility of this approach.

In this paper, H/sub /spl infin// control of a single flexible link with a shoulder joint is discussed. The cross-section of the flexible link is such that only horizontal vibrations are possible. Simulations were performed using a simplified model. An H/sub /spl infin// controller was designed that provides a fast step response with low overshoot, but inadequate disturbance rejection. Experiments were performed using a five-bar robot with one side joint locked. Using linear transfer functions obtained via system identification for several beam inclinations, an H/sub /spl infin// controller was found that has a good step response with the exception of large overshoot. Trajectory tracking is also shown. The performance is compared to that of a conventional PID controller.