Research On Multi-cylinder Synchronous Control Method Of Jacking-up Steel Platform Under Long Distance And Uneven Load

The technology of jacking-up steel platform(hereinafter refers to the platform)is commonly used in the construction of super high-rise buildings.The hydraulic system of the platform is used as the main driving device to jack and support the platform.Under the influence of external environmental factors and the uneven load,the platform may tilt or even collapse during the jacking process.Therefore,the good stability,safety and reliability of the hydraulic system and the synchronization and antiinterference of the jacking cylinder are the key factors deciding whether the system works properly.Based on the requirements of the function and technology in the hydraulic system,the article takes the hydraulic system of the platform of jacking-up steel platform and its synchronous control system as an object,designs the strategy of the hydraulic system and the synchronization control,and studies the dynamic response characteristics and synchronization performance of the system.Based on the mechanical structure of the platform and the cylinders' action,the article has comprehensively designed the hydraulic system,including its principle,circuit,cylinder,safety,component selection and so on.The article analyzes why the four cylinders are out of synchronization,and then synchronously control the cylinders according to the parallel closed-loop PID and adaptive fuzzy PID control algorithm.The article also conducts a force analysis on the hydraulic cylinder to deduce the mathematical model and open-loop transfer function of the single valve-controlled cylinder.An open-loop Bode diagram is used to analyze the stability,which shows the system is under-damped,stable and without significant overshoot.The hydraulic system simulation model is designed in the AMESim software.According to the component parameters of its selection,the two control models are established in MATLAB/Simulink and the corresponding control programs are written for co-simulation.The result shows,compared to the traditional PID control algorithm,the adaptive fuzzy PID control algorithm has a faster response time,smaller overshoot,and smaller synchronization error,which verifies the effectiveness of the algorithm and meets the synchronous control accuracy of the system.In order to obtain a better control performance,control strategies and control parameters need to be optimized.Based on parallel mode of synchronous control,the synchronization error will become larger and larger with time going on due to the relatively independent control of each cylinder.Therefore,the phased shutdown is required to eliminate the error,which greatly reduces the working efficiency of the system.Given that,a control strategy,based on a virtual axis tracking of the masterslave method,is proposed,which can eliminate the errors between the hydraulic cylinders in time and eliminate the accumulated errors without stopping the machine.This greatly improves the system's working efficiency and ensures that the synchronization errors are within the required range.