| In this paper,a hydraulic driving servo system for the vertical motion is designed based on a series of three-degree-of-freedom heavy-duty swing platform with vertical,roll,and pitch motions.The system includes four sets of drive subsystems.Aiming at the problem of fourcylinder synchronization of four groups of drive subsystems,the influencing factors of the dynamic characteristics of the drive subsystem are analyzed,and the load-initial pressure matching characteristics for the drive subsystem are obtained;the four-cylinder synchronization performance Evaluation index is proposed based on the least square method;Adopt cosimulation method to study the four-cylinder synchronous characteristic of hydraulic driving servo system for the vertical motion.On this basis,a synchronous control strategy based on load-initial pressure matching is proposed to further improve the synchronous performance of the four-cylinder vertical motion.The specific work of this article is as follows:First,for the heavy-duty swing platform,the load of the vertical motion is heavy(280t),the size is large(length and width are 13.7m and 12.5m,respectively),the motion amplitude is large(± 1.5m),and the speed is fast(1.89 m / s).It is more reasonable to design the drive system as hydraulic servo system.In order to increase the stability and safety during the vertical motion of the swing platform,four groups of drive subsystems are used for driving.Each group of drive subsystems includes a vertical drive hydraulic cylinder,a vertical load bearing hydraulic cylinder,a vertical drive valve group and a vertical load-bearing power source,wherein the vertical load-bearing hydraulic cylinder and the vertical load-bearing power source are used to balance the gravity of the system,and the vertical drive valve group controls the vertical drive hydraulic cylinder to drive the swing platform to complete the vertical motion.This system drives the swing platform on the basis of balanced gravity,which reduces the instantaneous power of the system,but at the same time introduces the problem of four-cylinder synchronization of four driving subsystems.Secondly,the dynamic model of vertical motion and the mathematical model of the driving subsystem were established.Aiming at factors such as eccentric load,initial pressure of the load-bearing power source,the length of the pipeline between the load-bearing power source and the hydraulic cylinder,and the inflation pressure of the load-bearing power source,dynamic response simulation of the drive subsystem was carried out.The analysis found that the partial load and the initial pressure of the load-bearing power source have a greater influence on the dynamic response of the drive subsystem.Based on this phenomenon and the mathematical model of the drive subsystem,the load-initial pressure matching characteristic formula is derived.The simulation results show that the application of the formula effectively reduces the effects of eccentric load and the initial pressure of the load-bearing power source,thereby verifying the validity and correctness of the formula.Thirdly,referring to the least square method,the four-cylinder synchronous performance evaluation method is proposed.Based on the study of the dynamic characteristics of the drive subsystem,a joint simulation analysis of the hydraulic servo system of the swaying platform was carried out,focusing on the dynamic response and synchronization performance of the swaying platform under different conditions of eccentric load and load-bearing power source initial pressure.The results show that the difference in initial pressure between the eccentric load and the load-bearing power source leads to an increase in the synchronization error of the sway platform vertical motion.Promote the load-initial pressure matching characteristic formula of the drive subsystem to the vertical-driving hydraulic servo system,and calculate the initial pressure of the accumulator group of each hydraulic drive device through the formula matching.The simulation results show that the initial load-bearing power source is set according to the calculated After the pressure,the error of the synchronous movement of the swing platform is reduced,which proves the correctness and effectiveness of the formula.Finally,the synchronization performance of the synchronous control strategy is studied.By comparison,the ring cross-coupling synchronous control strategy is proposed.The control strategy is improved based on the actual size of the swing platform.A ring cross-coupling dual PID synchronization control strategy is proposed.The joint simulation results show that This control strategy can reduce the synchronization error of vertical motion of heavy-duty swing platform to a certain extent,but the effect is limited.Therefore,a ring cross-coupled dual PID synchronization control strategy based on load-initial pressure matching characteristics is proposed,which can further reduce the synchronization error on the basis of load-initial pressure matching,thereby proving that the ring based on load-initial pressure matching characteristics Effectiveness of cross-coupled dual PID synchronization control strategy.During the process of studying the four-cylinder synchronization characteristics of the heavy-duty swing platform vertical hydraulic drive servo system,the four-cylinder synchronization performance evaluation index,the load-initial pressure matching characteristic formula and the ring-cross coupling double The PID synchronous control strategy enriches the theory of multi-cylinder synchronous control system,verifies the correctness of the design of the hydraulic servo system of the heavy load swing platform vertical drive,and guides the research work of the control strategy of the hydraulic servo system of the heavy load swing platform vertical drive.The successful development of the swing platform laid the theoretical foundation. |
