Backstepping adaptive position control for robotic manipulators

The paper presents a general approach for the design of an adaptive position control for a robotic system by the backstepping strict-feedback technique. The advantage of this control technique is that it imposes desired properties of stability by fixing the candidate Lyapunov functions initially, then by calculating the other functions in a recursive way. The adaptation of the parameters is made by the direct adaptive method. The results obtained by using this control method, which is valid for various types of robotic architectures, are very satisfactory when applied to a three d.o.f robot consisting of one prismatic axis (axis 1), and two others rotary axes. The results show that the robot follows exactly the triangular trajectory assigned to him. The trajectory tracking errors are negligible. Simulation results are included in order to evaluate the tracking performances and the global stability of the controlled system, and to justify the reliability of the proposed control technique