Trajectory Tracking Control of a 3-DOF Planar Wire-Driven Robot

Wire-direct-driven robots are a type of parallel manipulator. In this paper, a 3-dof planar wire-driven robot is stated. Taking this robot as the research object, the comprehensive research is made on how to maintain all wire tensions positive for all motion. Based on the idea of force/position hybrid control, the robot dynamics equation is established using the Newton-Euler method. Considering that wire-driven robots have the characteristics of nonlinearity, strong coupling and MIMO, a sliding mode control algorithm is utilized to realize the trajectory tracking. The control principle is based on the exponential approach law. A saturation function is introduced to solve the problem of chattering. Finally the robot control system is simulated and analyzed. The results of simulation experiments have shown that the tracking accuracy is much better and the control system has strong robustness.