| The electric actuator has the advantages of high positioning precision and fast transmission of the signal,and is widely used in the field of automation.The positioning control process must ensure the continuity of power supply due to the enormous power consumption,the thrust of the electric actuator is not large however.While the pneumatic actuators have the advantages of simple structure,large output force under the same caliber and clean working medium.However the compressibility of the air leads to the poor stability of the pneumatic system.The pneumatic position servo system actuators are affected by many non-linear factors,which have a certain impact on the positioning accuracy of pneumatic systems,and even lead to the significant degradation of the performance.The integrated electro-pneumatic compound actuator in our research can solve the problem that the power consumption of the electric actuator is large and the accuracy of the pneumatic system is not high.The integrated electro-pneumatic compound actuator is a low-power two-phase hybrid stepper motor connected through a large lead ladder screw and piston rod of a cylinder.A torque sensor is added between the stepper motor and the trapezoidal lead screw for the real-time monitoring of the torque variation of the electropneumatic compound actuator.In the compound actuator in our research,the electric actuator is used to drive the piston rod and load movement of the cylinder within the load range.At this situation,the electric actuator guarantee position accuracy and speed of the control system.In this paper,the advantages and disadvantages of electric actuators and pneumatic servo systems and their status quos of the applications and developments are introduced.The control methods of electric actuator and pneumatic balance system are summarized.At the same time,the application value and application direction of the integrated electricgas compound actuator are put forward aiming at the application of the integrated electropneumatic compound actuator.Furthermore,the basic principle and structure of the integrated electro-pneumatic compound actuator are introduced.The mathematical models of the electric actuator and the pneumatic system are established respectively.The stepper motor,the core component of the electric actuator,is introduced,and its mathematical model is established.The driving mode and acceleration/deceleration control mode of stepper motor are analyzed,and the closed-loop control system of electric actuator is determined.Subsequently,the simulation model of the electric actuator and the pneumatic system is built respectively according to the established mathematical models.The simulation results of the electric actuator,such as the no-load starting characteristic,the load characteristic and the anti-disturbance characteristic are analyzed.The simulation model of the position control system of the electro-pneumatic compound actuator is formed by combining the closed-loop control system of the electric actuator and the aerodynamic servo system,and the final simulation results are analyzed.After studying the structure and simulation model of the integrated electropneumatic compound actuator,its application and value of are discussed.According to the application requirements,the overall structure of the robot is designed and the forward and inverse kinematics analysis is carried out.According to the requirements of the application environment,a position-based impedance control method is proposed,and an impedance control model is built.The simulation results are analyzed by the simulation model of the impedance control of the electro-pneumatic compound actuator.Finally,under the premise of the unknown load,the experimental discussion on the integrated electro-pneumatic compound actuator is carried out.Through the construction of the PID controller and the coding of the PLC programs,the simulation of the positioning control of the integrated electro-pneumatic compound actuator is completed. |
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