Backstepping passivity adaptive position control for robotic manipulators

This paper presents a general approach for the design of an adaptive position control for robotic systems by the backstepping passivity strict-feedback technique. The advantage of this control technique is that it imposes desired stability properties by fixing for a given output, the storage, input and stabilizing functions with each recursive step of the system. Parameter estimation is made by the direct adaptive technique. The results obtained by using this control method, which is valid for various types of robotic architectures, are very satisfactory when applied to a four d.o.f robot consisting of one prismatic axis (axis 1) and three other rotary axes. The performance of the controller is illustrated by simulation results showing the tracking of a triangular trajectory. The results show that the robot follows exactly the triangular trajectory. The trajectory tracking errors are negligible.