Research On Positioning Control Of Pneumatic Muscles Actuator Servo-system

Pneumatic technology,which has a series of obvious advantages,is applied widely in industral production,and becomes a regular means of automation.However,PMA as a new type of pneumatic actuator,it has the advantage of simple structure,higher power to weight ratio,good flexibility,no leakage,long serving life.In this thesis,an improved static and dynamic mathematical model of PMA is developed by means of theoretical analysis,and a improved single neuron self-adaptive PID control tactics is adaped according to the characteristics of PMA servo system preperty to control the system.Firstly,a discussion was made to analyze the reasons why there is a great cliscrepancy between the ideal static mathematical model and the experimental results.As a result of the discussion,a new improved static mathematical model which take into account the influence of PMA's wall thickness,the friction between rubber tube and braided mesh shell and PMA's terminal radian is developedSecondly,it is developed that the PMA system can be treated as a pneumatic transmission system and PMA can be treated as a cylinder with variable cross section.At this point of view,a relatively simple nonlinear dynamic model of PMA is developoed based on the dynamic equation of pneumatic cylinder.Simulation of PMA dynamic property is done and the result shows that PMA servo system is of strong nonlinearity.Thirdly,due to the complex nonlinear dynamics of PMA and difficulties in obtaining accurate mathematical model,classical control method is not suitable for the system.A improved single neuron self-adaptive PID control tactics is presented to control the position of PMA servo system.The result of simulation with PID control method shows that conventional PID control causes system response's jitter easily,which can't get better dynamic characteristics,and has poor ability to adapt different pressure,while improved single neuron self-adaptive PID control not only improves system dynamic characteristics,but responses smoothly.PMA servo system's position control accuracy can reach±0.1mm.As concerning PMA servo system,improved single neuron self-adaptive PID control is feasible and appropriate.The work is the basis for taking other better effective methods to control PMA servo system's position.