Research On Low Time Delay And High Robust Control Strategy For Emergency Rescue Vehicle Driving Attitude

In recent years,disasters and accidents occur frequently,and show the characteristics of diversity and complexity.Emergency rescue vehicles play an important role as the main force of land rescue.In order to ensure the safety of the rescue equipment and avoid secondary injury to the injured,the vehicle body attitude should be stable during driving.The active suspension system can adjust the suspension parameters according to the external conditions and the running state of the vehicle to reduce the vibration of the vehicle.Therefore,by controlling the expansion and contraction of the active suspension actuator,the body attitude can be adjusted with the change of the road surface,so as to reduce the body bumps and vibrations caused by the road excitation,and improve the ride comfort and attitude stability of the vehicle in the rescue area with complex terrain.Low time delay and high robust are the characteristics that body attitude control must have.In this paper,the methods to reduce the time delay of body attitude control and improve the robustness of the system are studied,and a vehicle attitude control system with excellent performance is established,which provides support for the industrial application and promotion of active suspension control technology.This paper focuses on the following research work:(1)An active suspension actuator is developed.Firstly,considering the complex road conditions of emergency rescue vehicles,combined with computational fluid dynamics theory and dynamic grid technology,the complete fluid domain of passive suspension actuators is simulated;Secondly,the actuator structure is redesigned,and the structure is optimized through fluid simulation to improve the motion characteristics of the actuator.The actuator is developed as an active suspension actuator to meet the needs of the active suspension system on bumpy roads;Finally,the performance of the active suspension actuator is tested,which lays the foundation for the vehicle active suspension system to realize various advanced control algorithms.(2)The method of road level recognition based on vehicle speed is studied.Firstly,the dynamic model of the emergency rescue vehicle suspension system and the random road surface model are established to obtain the sprung mass acceleration and the suspension working space signal of the vehicle at each speed and at each level of road surface;Secondly,the most sensitive three statistical eigenvalues are selected by three-layer wavelet transform of the sprung mass acceleration signal and the suspension working space signal;Thirdly,ten neural network sub classifiers are designed corresponding to the ten gear speed,and the characteristic parameters are input into the sub classifiers of the corresponding speed for training one by one,and the road level is output;Finally,the accuracy of road surface recognition is verified by simulation.(3)A low time delay and high robust control strategy for vehicle body attitude is studied.Firstly,the vertical,roll and pitch motions of the vehicle body are decoupled,and the state space equations of vertical,pitch and roll motions are established;Secondly,the fast nonsingular terminal sliding mode controllers for vertical,pitch and roll motions are designed,and the finite time stability of the controller is proved.From the proof,it is known that the time for the system state to converge to the equilibrium state can be adjusted by setting the control law parameters of vertical,pitch and roll motions,which matches the control parameters required for the road level identification results.Finally,under the different road excitations,the simulation results of the proposed low time delay and high robust controller for vehicle body attitude are compared with those of skyhook control and passive hydro pneumatic suspension,which proves the superiority of the proposed control strategy in improving vehicle body attitude stability.(4)The control method of the electro-hydraulic servo actuator is designed.Firstly,the mathematical model of electro-hydraulic servo actuator force control system is established,and a reduced-order linear active disturbance rejection control is designed;Secondly,the convergence of the reduced order linear extended observer and the stability of the system are proved;Finally,the influence of different control gains on the controller is studied through simulation and experiment,and the tracking performance of the controller to the ideal force signal under different control methods is studied to verify the effectiveness of the reduced-order linear linear active disturbance rejection control,which provides guarantee for the performance realization of the low delay and high robustness controller designed in Chapter 4.(5)The whole vehicle test platform is built.Based on the chassis of the three-axis crane,the hydraulic system and the electric control system of the whole vehicle suspension system are built,and the test sample of the emergency rescue vehicle is finally formed;The control strategy is integrated,and the actual control effect of the control strategy proposed in this paper is verified by comparing the hydro pneumatic suspension system under the three working conditions of bump barrier,single bridge barrier and different level of pavement.