Workspace trajectory tracking control for two-flexible-link manipulator through output redefinition

In this paper, a control strategy and stability analysis for two-flexible-link manipulator are presented to track a desired trajectory in the workspace. The inverse dynamics problem is solved using virtual space and the quasi-static approach. Flexible manipulators are non-minimum phase systems when the controlled output is the tip position. To overcome this problem, an output redefinition technique is used. Two steps are presented to control the manipulator's tip position. First, assuming that the first link is stable, we develop the control law for the last link to stabilise the error dynamics using the feedback linearisation approach. The weighted parameter defining the non-collocated output is selected to guarantee bounded internal dynamics such that the output is as close as possible to the tip. Second, the same strategy is followed for the first link. Simulation results are presented to show good tracking of desired trajectory in the workspace.