# Pneumatic Rotary Actuator Position Servo System Based on ADE-PD Control
## 1 Introduction  
Pneumatic systems have been rapidly developed in industrial production because of the advantages of low cost, quick response, and great energy-saving [1; 2; 3]. The pneumatic rotary actuator can realize the change of rotation angle, so it is widely used in the rotation of the mechanical arm, the rotation of the platform, the opening and closing of the valve, and so on [4]. At present, the \"two points\" control method is the most common method to control the rotation position of a pneumatic rotary actuator, but it is difficult to realize the pinpoint at any position [5]. The pneumatic servo control system can control the motion trajectory of the cylinder and make the positioning accurate and efficient, which has become a hot research topic in pneumatic technology [6]. Short working strokes and great friction of the pneumatic rotary actuator make it difficult to apply the control strategy of ordinary pneumatic actuator to the pneumatic rotary actuator [7]. Scholars in various countries have made thorough studies of the servo control system of ordinary pneumatic actuator, but the research on rotation position control of the pneumatic rotary actuator is rare. Therefore, it is necessary to study the model establishment [8; 9; 10], parameter identification, and control strategy of the pneumatic rotary actuator deeply [11]. Many scholars utilized the feedback of the actuator's position signal or the two chamber pressure to control the position accuracy. [PERSON] et al. [12] studied the method that the position precision was well controlled by position and pressure feedbacks of the actuator. [PERSON] et al. [13] only used the feedback of the position of the actuator to realize the tracking control of the position by an Adaptive Backstepping Sliding Mode Control (ABSMC) method, which reduced the cost of the pneumatic system. Adding the feedback of the pressure can solve the phenomenon of position slip caused by the dead zone of the proportional valve. By further testing the performance of widely-used proportionaldirectional control valves, we conclude that the valve MPYE-5-M5-010-B has very high sensitivity with virtually no dead zone. Therefore, in this text, only the position signal is fed back to the controller, and then the result is output to the proportional valve, the fast and accurate response of the position can be realized. The establishment of the model can lay a good foundation for the research [14; 15; 16; 17], and the application of control algorithm is also particularly important. Proportional-Integral-Differential (PID) control is a typical representative of the classical control theory, which has the characteristics of a simple algorithm, good robustness, high reliability, and relatively easy adjustment. However, due to the serious nonlinearity of the pneumatic servo system, the simple classical PID cannot effectively control it. The scholars, based on PID control, added some intelligent algorithms to improve the control accuracy. [PERSON] [18] established a mathematical model for the servo system of a vane rotary actuator, and three parameters of PID control are optimized by fuzzy controller. [PERSON] et al. [19] applied a pneumatic servo system to the PAM manipulator with artificial muscles and combined the traditional PID controller with the Neural Network (NN) to design a nonlinear Neural Network PID controller which did not need training in advance and adaptively adjusted the parameters. But, Fuzzy control has low control accuracy, and the structure of the neural network is too complex. These limit the application in practice. At present, the development trend of pneumatic servo control systems is high efficiency and energy saving [20; 21; 22; 23]. Simplifying the structure of the system and controller and maintaining good control accuracy and stability [24] have broad prospects in industrial applications. [PERSON] et al. [25] applied Genetic Algorithm (GA) to the design of robust controller.