The Study Of Nonlinearity On The Backlash In The Mechanical Drive System

As a main nonlinearity in mechanical drive systems, backlash exists broadly in various systems such as machine tools, robots, astronomical telescopes, radars, artilleries, missile launchers, aerocrafts etc., and is an important factor influencing the dynamic and static properties of drive systems. Due to the non-differentiable trait of backlash, its compensation is much difficult. This brings austere challenge to the high-precision drive systems that have strict demand to quality and reliability. So, making deep study into the backlash nonlinearity in mechanical drive systems is much important in both theory and engineering.In this dissertation, backlash nonlinear control in the mechanical drive systems is studied .A switching control scheme with time optimal compensation is presented for the systems containing inner backlash. First of all, with a linear fuzzy PID controller used in contact period, the system output could track the expected target. And the reason of choosing a linear fuzzy PID controller is that it makes the system to have smaller overshoot, shorter regulation time and better dynamic response characteristic and steady-state characteristic. And then, a sliding control with time optimal surface is switched into when system enters the backlash. Finally, a supervising mechanism is introduced to find suitable time switching between linear fuzzy PID control and time optimal sliding control, ensuring BIBO stability of the whole system. The design can effectively eliminate the colliding disturbance resulting from the backlash and improve the robustness of the controller.