Design Of Self-tuning PID Hydraulic Control System Based On Fieldbus Control System

With the full application of electronic engineering and information technology in industrial production process,China is completing the automation and intelligence of industrial production.Hydraulic system,as an important transmission mode in traditional industry,is widely used in various heavy industry,military equipment and engineering vehicles.Therefore,it is necessary to design an intelligent control system for precise control of hydraulic devices.This paper studies the hydraulic transmission system of vehicle launcher.The main controlled object is the launcher driving hydraulic cylinder,and the controlled quantity is the displacement and speed of the hydraulic cylinder.Traditional control strategy can accomplish automatic control,but it lacks in control accuracy and control quality.It is difficult to overcome the non-linearity and parameter uncertainty of hydraulic system,and can not adapt to the parameter changes caused by frequent disassembly and assembly.In order to improve the control quality and adaptability of the hydraulic system,the fuzzy self-tuning PID control strategy is used after comparing different PID tuning algorithms.Fuzzy self-tuning PID control takes PID controller as the main body,but no longer uses fixed parameters,but adjusts parameters by Mamdani two-dimensional fuzzy tuning algorithm based on the data collected by sensors,which is more compatible with the controlled object.In this design,the open-loop transfer function of the hydraulic cylinder is obtained through the analysis of the hydraulic system,and the simulation environment is constructed by using SIMULINK to obtain a large number of PID parameters with different control indexes.Based on the above parameters,a fuzzy PID control algorithm suitable for the design is designed.According to the project requirements of the control process,the design completed the self-tuning PID hydraulic control system hardware configuration and software development.ACS880 frequency converter driver manufactured by ABB company and PSXCAN series proportional valve block manufactured by HAVE company are selected as actuators.The node of CAN controller based on DSP is designed,which not only has the function of collecting controlled variables such as pressure,flow and displacement,but also has the self-tuning PID control algorithm to complete the control task.On the industrial computer equipped with PCI card of CAN bus,the monitoring software is designed with MATLAB,and a friendly man-machine interface is made to visualize the data.CAN bus is chosen as the communication network and CANopen as the high-level protocol.The field bus control system with strong anti-interference ability,strong real-time performance,long transmission distance,simple structure and low cost is constructed.The monitoring software running on the computer can display the displacement value of the hydraulic transmission system uploaded by each control node,the pressure value of the pressure sensor,the flow value of the flow sensor and the alarm and other measurement parameters in real time,which verifies the correctness of the design scheme.The velocity and displacement curves of launcher rise test show that the control system meets the design requirements.