Research On Vibration Control Algorithm Of Seat Suspension Based On An Energy Saving Continually Controllable Electromagnetic Variable Damping System

Long-term exposure to vibration will cause severe health and security problems to drivers and passengers,especially for off-road vehicles,engineering vehicles and heavy vehicles with poor vibration environment.The drivers and passengers exposed to severe vibration environment usually work for a long time,which will not only cause health problems,but also cause fatigue driving and traffic accidents.An energysaving semi-active controllable electromagnetic damping(EMD)system,which can provide good vibration isolation performance and consume little energy,is proposed.An EMD system,which is consists of a permanent magnet synchronous motor(PMSM),a three-phase rectifier,a MOSEFT switch and an external resistance,is designed and tested firstly.Its model parameters have been identi fied based on the test results.The damping characteristics of the EMD system can be controlled by exerting PWM signal with different duty cycles on the MOSFET switch.A test bench is built to focus on the damping characteristics and energy harvesting pote ntial of the EMD system.The relevant control problems based on a seat suspension equipped with the EMD system are studied.In order to understand and eliminate the influence of the seat suspension friction,several control algorithms are studied based on the seat suspension friction.Frist of all,friction-displacement experiments are conducted and the Bouc-Wen friction model is selected to represent the seat suspension friction.The parameters of the Bouc-Wen friction model are identified by parameter identification technology.Applying a constant model to describe the friction is unreliable due to the long term tear and wear.An observer,based on the measurable data,i.e.acceleration,relative displacement and circuit current,is designed to estimate seat suspension friction force and used for the compensation of frictional influence in a robust controller.Finally,a state observer-based Takagi-Sugeno fuzzy controller is proposed to control the seat suspension friction with nonlinear and hysteresis characteristics directly.Considering the disadvantage of the semi-active device at high-frequency vibration control,we propose a hybrid control method,in which we can control the lowfrequency vibration with the friction observer-based robust controller,and switch to a low damping passive system at high frequency based on the dominant frequency of the vibration.In order to reduce the switching frequency of the EMD system,save communication resources and filter the vibration excitation,the event-triggered scheme is researched based on the EMD system.Considering the influence of seat suspension friction,we solved the co-design problem of controller-observer-event-triggered scheme and experiments are conducted to validate the effectiveness.The ultimate goal of the suspension system is to reduce the vibration transmitted from the uneven road to the human body.Therefore,it is crucial to study the relevant control algorithm of human-body-in-the-loop.A robust controller based on state observer and friction compensation is proposed to control the acceleration of human body and the unmeasurable human body signals is estimated by the state observer.In conclusion,all controllers designed in this thesis is helpful for the engineering application as it applies practically measurable variables as feedback and considers the performance of the semi-active device reality.The test results show that the energy consumed by the EMD system is very low and can be neglected.Therefore,this variable damping seat suspension can improve the ride comfort with ignorable energy cost.This thesis provides a new idea and solution for vibration isolation of seat suspension,which has certain academic and engineering significance.