Research On Joint Control Of Active Suspension And Brake For Reducing The Incidence Of Carsickness

With the increasing number of car ownership in the world and the increasing popularity of autonomous driving technology,the problem of motion sickness has become increasingly prominent.The difference between the road input of the front and rear axles during the running of the vehicle will cause the pitching vibration of the vehicle at different frequencies.However,the natural frequency of the pitching vibration of the passenger car is about 1.1 Hz,and the high-class car may even be lower than 1 Hz,which causes the pitching vibration of the vehicle.It will be amplified near the natural frequency.In addition,the driver's acceleration braking operation will also cause the pitching vibration,especially the “head-up” rebound of the vehicle in the late braking period,which is equivalent to giving the vehicle a tapping forced vibration,and its pitching vibration frequency is the natural frequency of the pitching vibration.According to numerous literature studies on the study of motion sickness,an important factor causing motion sickness is the low-frequency pitching vibration of the vehicle.0.1-0.5 Hz is the recognized motion sickness frequency,but vibrations exceeding this frequency band can also cause motion sickness problems at 0.8-2 Hz.The pitching vibration in the interval has the most obvious influence on the motion sickness problem.The traditional suspension of the vehicle has limited space for improving the pitching vibration.Therefore,the active suspension is first introduced to control the lowfrequency pitching vibration of the vehicle.Secondly,the braking control is caused by the “head-up” vibration which is easy to cause motion sickness in the later stage of the braking condition.Therefore,this paper further proposes that the combined braking system can assist the active suspension control in the non-emergency braking state to solve the pitching vibration in the late braking condition.Firstly,this thesis carries out the integrated dynamics modeling of the braking system and the active suspension system,and further establishes the road input model and the tire model.Secondly,the fuzzy adaptive PID active suspension control algorithm is designed.Simulink simulation results show that the active suspension and passive suspension under the fuzzy adaptive PID control designed in this paper control the pitch vibration in all stages of the braking process.Obviously,the rebound "headup" is almost completely eliminated in the suspension rebound in the late braking stage.From the evaluation of the low-frequency weighted averaging of the pitch angle acceleration,the fuzzy adaptive PID control method is reduced by 96.69% compared with the passive suspension.It basically offsets the pitching vibration of the braking process and reduces the incidence of motion sickness caused by pitching vibration.Subsequently,this paper deconstructs the pitching vibration of the vehicle in the late stage of braking from the dynamic point of view,and finds that if the cosine attenuation is simply applied to the braking torque in the later stage of braking,the lowfrequency pitching vibration of the vehicle body in the later stage of braking can be reduced.After adding the cosine-attenuation brake control proposed in this paper,the simulation results show that the cosine-damped brake control is 57.64% attenuated relative to the no-brake control from the averaging of the pitch-weighted acceleration,and the cooperative active suspension and cosine attenuation system.The dynamic control has a relatively no control attenuation of 98.33%,and the impact on the braking distance is 0.15%.The brake safety can be controlled below 10 cm without affecting the non-emergency braking state.Finally,a NI-based LabVIEW and Carsim hardware-in-the-loop joint simulation platform was built.The BP-based driver's braking intention recognition neural network is trained by using the platform.The driver's braking intention can be identified by the driver's braking behavior,and the coordinated control strategy application scene proposed in this paper is clearly positioned.The brake control is only in non-emergency state.Compile the collaborative active suspension and brake control program into a real-time controller to run the LabVIEW program and simulate it.The whole system runs smoothly,and the results show that the performance in the normal braking condition is consistent with the simulation results of Simulink,and does not affect the safety of emergency braking.Therefore,the joint control scheme of active suspension and brake control proposed in this paper not only theoretically attenuates the lowfrequency pitching vibration which is easy to cause motion sickness,reduces the incidence of motion sickness,and has the ability to expand in practical applications.