Research On Semi-active Control Of Vehicle Seat Suspension System

With the rapid development of driver’s requirements for ride comfort of commercial vehicles(truck)are increasing,thus the NVH performance of commercial vehicles has become the focus of the industry.How to reduce the vibration and noise of commercial vehicles in the process of driving,improve the sound quality,improve the driver’s comfort and safety has attracted more attention.As the force transmit component between human body and driver cab,the seat can alleviate the vibration and impact caused by road roughness and engine,which directly influences driver’s riding comfort.The use of semi-active seat can attenuate the vibration transmitted from the road to the human body through the cab,so the research on semi-active seat has high practical significance.This thesis studies the semi-active seat suspension systems based on cooperated study(3R119D592415),which can be divided by five parts.In the first part,MR fluid,MR damper and seat suspension systems are introduced.The advantages and disadvantages of passive,semi-active,fully active seats are compared and analyzed.The part reviews relevant research results,describes the development process of MR damper and its application in semi-active seat suspension.Combined with other scholars’ research,it shows that it is necessary to study at semi-active seat suspension.In the second part,due to the complex identification process and plenty unknown parameters of Bouc-Wen dynamic model,DBSCS optimization algorithm is proposed based on two meta heuristic optimization algorithms.General test functions are used to test the performance of the DBSCS algorithm.Compared with the test results of several commonly used algorithms,the proposed DBSCS algorithm has the advantages of both strong search ability and fast convergence performance.Based on DBSCS algorithm,the unknown parameters of Bouc-Wen dynamic model of MR damper are identified,and the forward dynamic model of MR damper is established.In the third part,the experimental data of dynamic characteristics of MR damper are preprocessed,and the BP neurol network is used to establish the reverse dynamic model of MR damper.The statistical characteristics of road roughness are analyzed and the time domain road input model is established by using harmonic superposition method.The half vehicle model of commercial vehicle is established.Wan & Schimmels human body model is selected by referring to relevant research,and the human-seat model is established by coupling MR seat suspension model.In the fourth part,the amplitude frequency characteristic of ideal skyhook control is analyzed theoretically,and the simulation model of skyhook control is established by the actual skyhook damper control equation.A weighted fuzzy PID control strategy is proposed,and the optimal weight coefficient is identified by the DBSCS algorithm.The simulation model of weighted fuzzy PID control is established based on incremental PID controller.The C class road simulation result shows that compared with passive seat,both skyhook and fuzzy PID strategy can effectively attenuate the vibration of human body,and the proposed weighted fuzzy PID strategy has better performance which reduces the acceleration response of human head by 27%.In the last part,the software of semi-active seat controller is programed based on STM32,and the hardware composition of the controller and the communication with AD sampling peripheral are introduced.The design requirement of MRD current driver is discussed.The current driver is designed based on amplifying circuit and the response characteristics are simulated in Multisim.The test circuit of current driver is built on bread board and the actual response characteristic is measured by oscilloscope.The step response time of the current driver is about 5ms,which can effectively meet the requirements of MR damper and in great agreement with the simulation results.