Research On Active Suspension Technology Of High-mobility Multi-axle Emergency Rescue Vehicles

The existing emergency rescue vehicles mostly adopt the passive suspension system,which is limited by its inherent properties;this system does not easily cope with complex and varied driving conditions,and it is difficult to ensure the off-road driving capability of the emergency rescue vehicles.The active suspension system can offset road impact by output energy,which can effectively ensure vehicle body stability and ride comfort under off-road driving conditions,and meet the performance requirements of emergency rescue vehicles for suspension system.This study combines National Key Technologies R&D Program "Key Technology Research on Special Chassis and Suspension for High-mobility Emergency Rescue Vehicle(Including Fire Fighting Vehicle)”(Project Number: 2016YFC0802902),which aims to improve the body stability and ride comfort of a multi-axle emergency rescue vehicle.The active suspension system and the control algorithm have been deeply investigated.The following are the main research works of this study.(1)A servo control algorithm for active suspension hydraulic actuator is designed.To achieve the design requirements of the servo control algorithm,a two-degree-of-freedom dynamic model of a single active suspension for a multi-axle emergency rescue vehicle is established.The dynamic characteristics of the active suspension hydraulic actuator are analyzed,and the nonlinear model of the actuator is established.A nonlinear adaptive PID controller based on anti-windup algorithm is also proposed.The effectiveness of the controller is verified via simulation analysis,thus laying a foundation for the design of subsequent active suspension controller.(2)An active suspension sliding-mode predictive control algorithm is designed.A nine-degree-of-freedom dynamic model of the vehicle is established.The active suspension predictive model based on Taylor expansion algorithm is constructed.The active suspension sliding-mode predictive controller is designed on the basis of the model predictive and sliding mode control.The introduction of T–S fuzzy model and adaptive algorithm reduces the influence of model uncertainty on the control system and improves the real-time performance and robustness of the system.The closed-loop control of the active suspension system is realized by combining with the nonlinear adaptive PID servo control algorithm of active suspension described above.The simulation analysis reveals that the controller has good control effect on improving the stability and ride comfort of the multi-axle emergency rescue vehicle.(3)A robust H2/H? based active suspension and all-wheel steering joint control algorithm is designed for emergency rescue vehicles under steering conditions.The dynamic characteristics and stress of the multi-axle emergency rescue vehicle and tires under the steering condition are analyzed.The dynamic model of the active suspension and multi-axle steering system and the model of the tire are also established.A joint controller is constructed by applying robust H2/H? control theory,aiming at the nonlinear action and external disturbance of the coupled system.The joint controller design is verified with the road condition and wheel angles as control system inputs.The simulation results indicate that the joint controller further improves the stability and ride comfort of the vehicle while ensuring the steering capability.(4)A special test platform for active suspension system is designed and set up to test and verify the active suspension sliding-mode predictive control algorithm proposed in this study.The design and construction of the mechanical,hydraulic and control system of the special test platform are carried out.The proposed active suspension sliding-mode predictive control algorithm is used to conduct the obstacle test,with the pulse and continuous undulating pavements as the test conditions.The practical application effect of the active suspension control algorithm is further verified by comparing the test results of the passive suspension system.