State Observation And Semi-Active Control Strategy Of Commercial Vehicle Seat Suspension

The driving condition of commercial vehicle is complex and the running time is long for one time. Driving on a bumpy road makes the driver expose in a bad vibration environment for a long time, which is harmful for the driver’s health. Usually we selecte more comfortable seat cushion and adjust the seat structure in the traditional passive seat. However this will only bring limited improvement of vibration transmission, and result in the the seat vibration amplification with low frequency excitation. Recently commercial vehicles use the scissor seat with a shock absorber; however there is an irreconcilable conflict on the shock absorber damping coefficient selection:suspension with small damping coefficient can improve the seat comfort, but will increase the seat suspension travel on the other side. Using semi-active seat suspension system can balance the seat comfort and smoothness effectively, so it has very important practical significance to study semi-active seat suspension system for commercial vehicle in this paper.This paper will will be based on the commercial vehicle semi-active seat suspension system development project, use the semi-active seat suspension with solenoid valve type damper as the research object. The research content will focus mainly on how to consider the effect of human body vibration in the establishment of seat suspension dynamics model; how to design the control strategy to acquisite the state variables in the actual engineering application with the least sensor observations. The work will be carried out from the following aspects in this paper:1) Build the people-seat suspension system dynamic model. Considering the influence of human body vibration on the vibration of seat suspension system, we will add the human body vibration model in suspension model; according to the national standard, which presents the spectral density power of commercial vehicle cab floor to seat vibration excitation input, we will obtain the seat suspension vibration excitation input in time domain through the method of time domain reconstruction.2) Develop the semi-active control strategies of seat suspension system. The design must be simple in engineering application, so we will contrast different skyhook control strategies by frequency response characteristics of semi active suspension system; adopt genetic algorithm to optimize the control parameters according to different driver quality section; analysis the response of semi active suspension system from the point of view of the time domain and frequency domain, contrast passive suspension and semi-active suspension through the SEAT value and VDV value; analysis the degree of improvement for the driver health vibration environment visually by the vibration exposure for the driver.3) Design the state observer for seat suspension system. A state observer will be constructed for four freedoms driver seat suspension system by using the method of Caiman state observation, with the acceleration signal measured on an acceleration sensor in the up-bottom of the seat suspension. So it can observe on the speed of up-bottom seat suspension and damper relative velocity.4) Compile the driver mass online identification algorithm. In order to reduce the influence for state observation accuracy rate of driver quality, we will identify the driver’s quality by implementation of the recursive least square algorithm; the identification error must be controlled within 5%. The parameters of state observer will be updated by the driver quality identification.5) Construct a seat bench test. To verify the stability and practicability of the semi-active seat control system from the angle of comparison test, the seat bench test will be given sinusoidal vibration with different amplitude and different frequency excitation.