Research On The Control Of Electro-Hydraulic Servo System For Extruder Based On DSP

Extruder is widely used in industrial production and plays a significant role in infrastructure and national defense industry. During working process, the extruder needs to achieve precise control of displacement and keep the extruder working in a steady speed in order to improve the production efficiency and ensure the quality of products. Therefore, This paper carries out study on position and speed hybrid control.Firstly, with studying the operational principle of the extruder and the movement performance of electro-hydraulic servo system, hydraulic part model and control part model of the hydraulic servo system are established respectively in AMESim and Simulink, and the co-simulation model of electro hydraulic servo system is built furtherly.Secondly, as the extrusion speed is a decisive element to extruder control, the speed control is set as the main part and the displacement control is the minor one. In the process of designing speed controller, several kinds of speed control models are established according to the three speed control stage of extruder of medium speed moving, low-speed extrusion and high speed return, which include fuzzy PID track following control model, PID speed control model and subsection PID speed control model. The results show that the subsection PID speed control model has the best control performance but can’t achieve a high displacement precision during the extruding period. For improving a displacement precision, Several kinds of displacement control models are designed and simulated, which include PID, fuzzy PID, Bang-Bang+PID and Bang-Bang+fuzzy PID displacement control model. The simulations show that Bang-Bang+ fuzzy PID displacement control model achieves fast response speed, high stability precision, well anti disturbance ability and robust performance. Based on the speed and displacement modeling analysis, position and speed hybrid control model is built and debugged on the co-simulation model. The result shows:the extruder have the function of infinite speed variation, achieve precise control of displacement and keep the extruder working in a steady speed in order to improve the production efficiency and ensure the quality of product.Finally, the PID closed-loop control experiment with the controller of DSP is conducted on the electro-hydraulic servo control platform, the result shows that the system has good static and dynamic performances, and the electro-hydraulic servo system can basically meet the control requirements.