Studies of adaptive control methods based on VSC for trajectory tracking of robotic manipulators

Control methods are studied based on Variable Structure Control(VSC) thoery to make the trajectory tracking errors and response time of robotic manipulators be significantly reduced. By combining VSC and PID, a new control method has been proposed intially to improve the precision of the trajectory tracking. Furthermore, an adaptive fast control method based on VSC, which is to improve the performance of the reaching motion of conventional VSC method, is presented. The reaching motion would be optimized by proposing an adaptive reaching velocity, which can adjust to the changes of the errors as well as reduce chattering. The simulation results of a three degrees of freedom(DOF) robotic manipulator model have demonstrated that the performance of the two proposed methods is stable, with faster responses. Actually, the effectiveness of adaptive fast control method based on VSC has been further confirmed via experiments by the control of a two DOF robotic manipulator. Thus, the proposed adaptive fast control method based on VSC is superior to the conventional control methods.