The Research Of Clamping Force Control System On Pneumatic Manipulator

Pneumatic manipulators are widely used in industrial production lines such as automobile industry, pharmaceuticals industry, food processing industry and so on, especially in the harsh circumstances like high temperature, flammable, explosive, dust, magnetic, radiation. In some of these situations robots are required to crawl the fragile, yielding object, which need a high requirement on clamping force control the of robots. Therefore, it has become an important aspect in the force control of the pneumatic manipulator, which has better theoretical research and practical engineering value. Based on the domestic and international documents, this dissertation summarizes the current research status of pneumatic proportional servo force control system and pneumatic manipulator. The structure components and working principle of clamping force control system are introduced and analyzed in this dissertation. System performance indicators are proposed based on these analyses.The factors which affect accuracy of the clamping force control are proposed, and the theory of the factors is studied. Then we obtained its causes and improvement measures. Reasonable assumptions and approximations in the linear process based on the established pneumatic manipulator clamping force control system mathematical model to analyze the frequency is undesirable, including system modeling features, dead zone characteristics of proportional valve and the nonlinear characteristic of pneumatic system and other factors will affect the modeling accuracy. This dissertation is mainly from points of the dynamic characteristic of pneumatic system, cylinder friction and creep phenomena of nonlinear pneumatic system for correlation analysis. Pneumatic manipulator clamping force control system transfer function of the frequency domain characteristics were analyzed by MATLAB software.As the sliding mode control has a good anti-interference ability and capacity of the model parameter perturbation, for a series of non-linear factors of compression, friction, air pressure and load changing in the pneumatic system, the above control strategy is adopted to solve the unmodeled part of the pneumatic system dynamics and bounded disturbances, so it can improve accuracy and stability of the aerodynamic servo system. To overcome the chattering phenomenon of sliding mode control system, through the analysis of controller designing, selection of quasi-sliding mode control designing and design a sliding mode controller based on saturation function of reaching law to avoid or reduce the chattering.Pneumatic control system combined with controller is simulated in the Matlab software. Simulation result is compared with no controller or the control system with PID controller. Simulation result shows that the system combined with intelligent variable structure controller has better robustness. The system response speed and stability are improved. The control accuracy is improved from2.6%to0.8%. And the Bandwidth is improved from0.53Hz to5.54Hz, which gets a better comprehensive control effect.