Sliding-mode controller design of a single-link flexible manipulator under gravity

This is follow-up research of the regulator design for a single-link flexible manipulator using the sliding-mode technique (Yeung and Chen 1989). In this paper, we have extended the controller design for the regulation problem to that for the tracking problem when the single-link manipulator is moving on a horizontal plane. In addition, by placing strain gauges along the flexible arm (Hastings and Book 1985) we can substitute strain measurements for the need to estimate modal func- tions, which is a step close to implementational reality. Extension of the controller design is also carried out to the regulation of a flexible arm under gravity. A PID compensation is needed to compensate for the steady-state offset due to gravity. The controller design presented is simple and requires no inertia matrix inversion, no modal estimation and no payload forecast. Simulation studies demonstrate the robustness of the control against input disturbance and payload variations.