The Research On The Servo Controller Of Pneumatic Rotary Actuator

Pneumatic technology, which has a series of obvious advantages, is applied widely in industry production more and more, and becomes a rigueur means of automation. Entering into 1990's, pneumatic technology is largely beyond the traditional blind area and comes through a quickly develop. As the leading study domain, pneumatic servo technique has a regard for the people. Pneumatic servo positioning technology can realize high accuracy arbitrarily point automatic positioning when cylinder moves in high velocity and break through the traditional pneumatic positioning method. Based on the requirement for engineering upgrading of pneumatic automatic equipment that has advantages such finer feasibility and higher ratio of property and price in middle and small enterprises, this paper introduced a low cost linear cylinder position control system based on a proportional pressure valve. The emulation result indicated that it has a satisfactory control performance, thus, it can be expected to generalize and utilize in variously engineering regions. In the field of industrial automation, there is a lot of requirements for rotation position servo control. Therefore, it has practical value to study on the pneumatic rotation position servo control.Pneumatic rotary actuator is an actuating device of rotate motion used widely in pneumatic system. However, its small stoke and large friction torque make it more difficult to implement angular position servo control of high performance. At present, the positioning precision could not meet the practical requirement. In this paper, a pneumatic rotary actuate position servo system with proportional pressure valves as the control devices is studied. The study is conducted in the following aspects: method of establishing linear model, compensation method of nonlinear friction, control strategy and so on. In order to obtain a better pneumatic servo control system.First of all, this paper has analyzed the characteristic of rotary and flow promotional valve, described the load and friction situation .On the basis of the analysis, this paper has derived the flow-pressure equation and Balanced equation of system, thus set up the non-linear mathematics model, has carried on the rational linearization.The system steady-state error and the stick-slip phenomenon caused by the nonlinear friction are analyzed. A dual-loop control strategy with friction compensation for the system are proposed. The controller has an inner pressure difference control loop and an outer velocity control loop. In the outer loop, a simple friction compensator is used to eliminate the negative effects of the nonlinear friction. Simulation results show that the system performance using the proposed control strategy is better than that using the control strategy with position control loop only. At the end, the pivotal job of this paper is to detailed research and design the control strategy, and to confirm the feasibility and the validity through the simulation. According to the system characteristic which is easily influenced by disturbing effect, my paper has analyzed and compared traditional PID control and grey PID. This method received good result. The simulation results indicated that grey PID is stable and effective. The system has enhanced both the anti jamming and the anti perturbation ability.