Efficiency Analysis And Control Strategy Research Of Electro-hydraulic Servo Steering System For Multi-axle Vehicle

Multi-axle vehicle is a large engineering equipment necessary for national defense modernization and civil infrastructure construction.With the development of China’s economy,the market demand for multi-axle vehicle has increased year by year.As one of the core systems of multi-axle vehicle,the multi-axle steering system directly restricts its stability,flexibility and high efficiency,and it has also become an important indicator of the research and development for moderm large wheeled vehicle.Therefore,it’s of greet significance to deepen the basic theoretical research of multi-axle steering technology so as to improve the steering performance of multi-axle vehicle and overcome some drawbacks in multi-axle steering system.The key that affects multi-axle steering performance lies in its abilities of driving and dynamic steering.Electro-hydraulic servo steering is favored for its capability to balance both large loads and high-precision dynamic steering.However,the low efficiency of the existing electro-hydraulic servo steering system has severely limited its technological breakthrough.Therefore,based on the theoretical research of the electro-hydraulic servo steering system,this paper analyzes the efficiency characteristics of the steering system and studies the design of a compound control strategy for the pump and valve system,aiming to achieve energy-saving and high-precision control of the steering system.Firstly,based on the physical model of the steering system and its basic principle,the theoretical model of single-axle electro-hydraulic servo steering system efficiency is established.Based on the Lagrangian dynamic equation,a nonlinear mathematical model of the steering mechanism is established.The mathematical model of the hydraulic control system for the valve-controlled double steering cylinders is obtained.A mathematical description among the working pressures of important system components is obtained.The efficiency of hydraulic control system is theoretically studied and a mathematical model for the efficiency of the electro-hydraulic servo steering system is established.Second,based on the mathematical model of steering system efficiency,the static efficiency characteristics of the system are analyzed.A static efficiency model for single-axle electro-hydraulic servo steering system is built.After analyzing the influence of mechanical structure on the static efficiency of the system,a simplified model of system static efficiency is established.The basic efficiency characteristics is revealed through system static efficiency analyses under different operating conditions.Considering the influence of system parameters on the static efficiency,a law explicitly describing the influence between key system parameters and system efficiency is obtained.Then,based on the static efficiency analysis results of steering system,an energy-saving and high-precision control strategy based on the compound control for pump and valve is designed.Focused on the core issues for saving energy and reducing consumption of electro-hydraulic servo steering system,the existing steering system is improved,and the corresponding energy-saving control strategy is designed.Combined with energy-saving control and traditional PID control strategy,a composite control strategy for the pump and valve is proposed,and a comprehensive control model of the system is established.Based on genetic algorithm to adjust the parameters of PID,the energy-saving high-precision control of the electro-hydraulic servo steering system is achieved.Finally,a single-axle electro-hydraulic servo steering test system is built to verify the accuracy of the theoretical model of the steering system efficiency.The static efficiency test scheme of the steering system is designed,and an electro-hydraulic servo steering test system is built combined with the MLC controller and the LabVIEW data acquisition system.The accuracy of the mathematical model of the steering system efficiency is verified by comparing the measured results of the system static efficiency with the simulation analysis results.The effect of key parameters on the efficiency of the system under actual operating conditions is studied,and the corresponding influence degree on efficiency is defined.The innovation of this paper is to establish a nonlinear mathematical model and an efficiency mathematical model of single-axle electro-hydraulic servo steering system.Combined with actual loading conditions,the system static efficiency of the system under different operating conditions is analyzed.It reveals the basic efficiency characteristics of the system so as to provide a theoretical guidance for the energy-saving and high-precision compound control of the electro-hydraulic servo steering system.Aiming at the core problem in low system efficiency,a high-precision and energy-saving compound control strategy based on pump-valve control is designed.By taking into account the control accuracy and working efficiency of steering system,it can achieve both energy-saving and high-precision of the electro-hydraulic servo steering system.