Backstepping control design of flexible joint manipulator using only position measurements

A tracking controller is presented for flexible joint robot manipulators with only position measurements and without any restrictions on the joint stiffness gains. The controller is developed based on the integrator backstepping design method and on the two observers: one for the filtered link velocity errors and the other for the actuator velocities. The proposed controller achieves exponential tracking of link positions and velocities while keeping all internal signals bounded. It also guarantees exponential convergence of the estimated signals to their actual ones.