Study On The Static And Dynamic Performance And Control Strategy For McKibben Pneumatic Artificial Muscles

As a new kind of air-operated component, Pneumatic Artificial Muscles has drawn extensive attention of scholars at home and abroad. In this paper, McKibben's Pneumatic Artificial Muscles were studied, its mathematical model was built and a relatively more integrated mathematical model of Pneumatic Artificial Muscles was constructed and tested through experiments and emulations under still and dynamic state. Based on analysis of the characteristics of Pneumatic Artificial Muscles control system and using an associative method of faintness-control and forecasting P.I.D control, a faintness-forecast P.I.D control strategy of McKibben's Pneumatic Artificial Muscles positioning control system was designed.Firstly the deficiency of the model built by Chou was analyzed, and a more practical molding of Pneumatic Artificial Muscles under ideal state was constructed. Then by analyzing the causation of difference between McKibben's Pneumatic Artificial Muscles' output strength and factual output strength, focusing on two main factors-rubber's elasticity and friction between rubber sleeve and fibre meshwork, a more integrated static-state mathematics model of McKibben Pneumatic Artificial Muscles was built. Experiments and computer simulations on two types of Pneumatic Artificial Muscles(MAS-10-700N-AA-MC-K and MAS-20-300N-AA-MC-K) revealed their static mechanical characteristics and validated the correctness of the static mathematics model.Secondly, Pneumatic Artificial Muscles system was studied as an air-pressure transmission system. Regarding Pneumatic Artificial Muscles as equivalent function area cylinder and based on cylinder dynamic energy- balance equation, experiments and computer simulations of the same two types of Pneumatic Artificial Muscles were done. The results showed the dynamic working characteristics of the Pneumatic Artificial Muscles and validated the correctness of the dynamic energy- balance equation. The transfer function and basic control equation of Pneumatic Artificial Muscles' closed-loop control system were deduced, too.Afterward, considering obvious nonlinearity and following difficulty to build accurate mathematics model, a faintness-forecast P.I.D control strategy of McKibben's Pneumatic Artificial Muscles was brought forward on base of systemic analyse of Pneumatic Artificial Muscles' characteristics. Classical PID control system and faintness-forecast P.I.D control system were compared, faintness-forecast model was built through the way of faintness identification, PID parameters were properly designed by forecast optimizing-implement, then Pneumatic Artificial Muscles system could be studied under appropriate control. Simulation results showed that under classical P.I.D control system it's hard to gain good control effects due to diversifications of inertia load and journey, and three parameters(inverse proportion, integral, differential coefficient)were hard to make certain, while faintness-forecast P.I.D control could improve dynamic capability, shorten response time, and reduce over-adjustment. It has been proved that for McKibben's Pneumatic Artificial Muscles control system, faintness-forecast P.I.D control strategy is feasible and rational.