Abstract: According to the characteristic of friction in machine system, the friction force result in scalar case is extended to the vector space case, which makes the control problem of the external stochastic disturbance in robotic systems embodied. First, the robotic dynamical model based on Lagrange equation is transformed into a linear state equation via feedback control technique. Then, based on the linear state equation together with the Lyapunov stability theory, the robust compensated controller corresponding to the general trait of friction is designed to attenuate the effect coming from the unexpected friction force of robotic control systems. The aim is that the actual movement trace can converge to the desired position asymptotically in global sense. The designed controller exhibits some merits such as clear theory, easy design, and good robusteness and so on. Moreover, a completed theory proof is given. Finally, the simulation test results are given by taking a two-joint robot as an example. From the comparison between the two different simulation results which are obtained by using different controller, it can be seen that the presented robust controller performs well in application.

Key words: Global asymptotic stability, Friction, Robot, Robust control