Research On Active And Passive Control Of Vibration Isolation System Of Vehicle Seat

During vehicle driving,tire and suspension have isolated the vehicle body from road-induced excitation,which will otherwise be transmitted to the passengers.In the design of tire,handling stability and riding comfort are two conflicting requirements.Since suspension must support the vehicle over a range of loading conditions,maintain directional and attitude control during handling maneuvres and also provide isolation from road surface irregularities,the parameter and structure optimization of suspension is also limited.Active vehicle suspension system,which can ensure both handling stability and riding comfort,have been extensively researched in order to find a viable alternative to the conventional suspension system.But it hasn't been widely used.Studies show that most passengers are exposed to low-frequency and high-amplitude vibration,which is a major factor in health disorders.It may cause damage to viscera and spinal system over a long period.Seat is the last vibration isolation part in the road excitation transmitted to human body,the active control system of seat can effectively attenuate vibration and enhance riding comfort.Furthermore,the optimization of seat has little effect on the vehicle performance,especially driving stability,and is easy to implement.This article takes the seat suspension as the research object,carries on the active control system's design and the simulation verification,in order to enhance the seated human body's riding comfort.In this paper,considering the problem of poor low-frequency tolerance of the human body in the sitting position,a six-degree-of-freedom "wheel-body-seat,body"vibration isolation system model was established,only considering the vertical,pitching movements of the body and the vertical movement of the seat.Acceleration based Particle Swarm Optimization algorithm is used to optimize the parameters of the seat suspension under the premise of ensuring that the vertical most sensitive frequency range of the human body is located in the damping area and avoids the natural frequency of the vehicle body,which improves the vibration isolation performance of the low frequency band.In order to further attenuate the vertical acceleration response amplitude of the "seat-human" in low frequency band,a linear quadratic optimal controller is used to control the seat suspension system,and a state observer is designed to ensure the system is fully measurable.The traditional controller weight matrix is determined by human experience and it is easy to fall into the local optimum.This paper uses the acceleration based particle swarm optimization algorithm to optimize the controller weight matrix.Comparing with Simulink simulation results of parameter optimization system and optimal control system based on genetic algorithm,the optimal control seat suspension system based on acceleration based particle swarm optimization algorithm can effectively attenuate the vertical most sensitive frequency segment of the human body and greatly enhance riding comfort.Because the fully measurable state variables of the optimal control system often depend on the state observer,an exact mathematical model needs to be determined.In order to facilitate the practical application,PID control and fuzzy control systems are proposed.They have the advantages of simple structure and no need to determine the controlled system model.The designed PID controller can effectively reduce the vertical acceleration of the "seat-human body",but due to the fixed parameters,online setting cannot be achieved and the control performance is limited.Due to the small value of the controlled quantity and poor control accuracy.Using fuzzy control alone cannot effectively improve the ride comfort.Using fuzzy control to achieve online tuning of PID control parameters,a fuzzy PID controller was designed.This not only solves the contradiction between control performance and robustness,dynamic and static performance,but also adapts well to time-varying operating conditions.Compared with the simulation results of the passive seat suspension system,the fuzzy PID control system significantly reduces the vertical acceleration of the "seat-human body" and effectively improves the riding comfort of the most sensitive vertical frequency segment of the sitting body.Using ADAMS,the virtual prototyping coupling model of "scissor seat-human body" was established,and the communication link with MATLAB/Simulink was established through ADAMS/Controls module.Through the joint simulation,it is verified that the fuzzy PID control system can effectively reduce the vertical acceleration of the human body and enhance the ride comfort.