Workspace tracking control of two-flexible-link manipulator using distributed control strategy

A distributed nonlinear control strategy for two-flexible-link manipulators is presented to track a desired trajectory in the robot's workspace. the inverse dynamics problem is solved by transforming the desired trajectory from the workspace to the joint space using an intermediate space,called virtual space,and then using the quasi-static approach. to solve the nonminimum phase problem,an output redefinition technique is used. this output consists of the motor's angle augmented with a weighted value of the link's extremity. the distributed control strategy consists in controlling the last link by assuming that the first link is stable and follows its desired trajectories. the control law is developed to stabilize the error dynamics and to guarantee bounded internal dynamics such that the new output is as close as possible to the tip. the weighted parameter defining the noncollocated output is then selected. the same procedure is applied to control and stabilize the first link. the asymptotical stability is proved using lyapunov theory. this algorithm is applied to a two-flexible-link manipulator in the horizontal plane,and simulations showed a good tracking of the desired trajectory in the workspace. © 2013 fareh raouf et al.