NONLINEAR ULTIMATE BOUNDEDNESS CONTROL AND STABILIZATION OF A FLEXIBLE ROBOTIC ARM

We treat the question of control of an elastic robotic arm of two link s. Of course, this approach can be extended to other elastic arms. A n onlinear ultimate boundedness controller (UBC) is synthesized such tha t in the closed-loop system the joint angle tracking error is uniforml y bounded and tends to a certain small neighborhood of the origin. The controller includes a reference joint angle trajectory generator and integral error feedback. Although the joint angles are controlled usin g the UBC, elastic modes are excited. A feedback stabilizer is designe d for the linearized model including the UBC about the terminal state that is switched only in the vicinity of the equilibrium state for sta bilization. Simulation results are presented to show that in the close d-loop system including the UBC and the stabilizer accurate joint angl e trajectory following and elastic mode stabilization are accomplished in the presence of uncertainty.