Research On The Method Of Determining The Delay Boundary Of CAN Bus Communication For Intelligent Valve

With the continuous advancement of intelligent construction machinery,intelligent valves with communication functions have attracted widespread attention and research as the core of construction machinery.Applying bus communication technology to intelligent valves can greatly simplify system wiring,enhance anti-interference,and improve standardization.However,the application of bus communication technology can also bring problems such as data transmission delay,data packet loss,and bus shutdown,affecting the control performance of intelligent valve systems,and even causing control failure.Therefore,it is crucial to analyze the maximum communication delay boundary allowed by the intelligent valve system and ensure that it operates within the allowed communication boundary.Therefore,this article takes the delay caused by CAN bus communication,which is the most widely used in intelligent valves,as an example to conduct the following research:(1)Introduce the control structures of centralized and distributed intelligent valve systems,design CAN bus communication data instructions and formats,and analyze the data transmission process of intelligent valves,the delay links generated by CAN bus in the intelligent valve system,and the time used to transmit each delay link of a frame of data.(2)A mathematical model of a single valve position closed-loop control system is established in two types of control structures,centralized and distributed.Using the Lyapunov Krasovskii functional and free full matrix method,the maximum communication delay boundary of the forward channel,feedback channel,and given signal after the communication delays of the three links are superimposed is derived while ensuring system stability.Verify the accuracy of the delay boundary determined during data transmission in the system using MATLAB/Simulink;Study the impact of sampling period,packet loss in data transmission,and disturbance in CAN bus transmission on the delay boundary of displacement sensors with CAN bus interfaces.Obtain the allowable sampling period range of the sensor,the allowable packet loss range for data transmission,and the allowable disturbance range during CAN bus transmission within the maximum communication delay boundary.(3)In two types of control structures,centralized and distributed control,establish a communication delay mathematical model for the closed-loop control system of the multi way valve position,and use integral inequality and free weight matrix to derive the communication delay boundary that ensures the stability of the multi way valve system.Taking CAN bus communication as an example,considering two scenarios: no delay and random delay within the communication delay boundary,to verify the accuracy of the maximum delay boundary.(4)Building a multi-channel intelligent valve position closed-loop control system experimental platform,design the hydraulic system and electronic control system of the experimental platform,and conduct reliability experiments,load rate experiments,and delay characteristic experiments on the CAN bus communication system.The experimental results show that when the CAN bus load rate is within 50%,the stability of the single valve position closed-loop system can be met;The closed loop control system of single valve position can realize step response and sinusoidal following response of different target displacement;Within the allowed communication delay boundary,the response time and stability of the single valve position closed-loop control system can be met;Under the conditions of a sampling period of5-11 ms,interference data information less than the original information,and CAN communication packet loss within 10%,the communication delay boundary of the single intelligent valve position closed-loop control system is not affected,and the stability of the single valve main valve position control system meets the requirements;In both centralized and distributed control structures,the multi way valve position closed-loop control system equipped with CAN bus can achieve synchronous control of the position of the triple main valve within the allowable range of their respective communication delay boundaries.Among them,centralized control takes a shorter time and has poor synchronous control performance;The distributed control structure takes a long time and has good synchronous control performance.