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The Parameters Optimization Of A SUV's Hydraulically Interconnected Suspension And Study On Its Body Height Control

Posted on:2018-11-05Degree:MasterType:Thesis
Country:ChinaCandidate:X Z LiuFull Text:PDF
GTID:2322330542469714Subject:Mechanical engineering
Abstract/Summary:PDF Full Text Request
Hydraulically interconnected suspension can significantly improve the anti-roll performance and tire road holding ability of vehicle,and exert no obvious side effect on ride comfort.Moreover,through the operation of charging and discharging oil,the hydraulically interconnected suspension can adjust the height of the vehicle body;the main function of body height control is to change the ground clearance of vehicle chassis,which is important for improving vehicle safety,passing capacity and fuel economy.First of all,according to the theory of multi-body system dynamics,this paper establishes a seven degrees of freedom whole vehicle dynamics model and a whole car mechanical-hydraulic coupling dynamics model included hydraulically interconnected suspension,then establishes four wheel correlated road model to obtain a group of four wheel vertical input data,using the real vehicle test data verifies the accuracy of this whole vehicle model,and makes a brief analysis of the influence of key hydraulic parameters on vehicle performance;With vehicle body height control as main constraint,and the body acceleration and roll angle as the optimization objective function,the NSGA-II algorithm is used for optimizing key parameters of hydraulically interconnected suspension.Then,this paper establishes a 1/4 vehicle model and analyzes the effect of PID control,fuzzy control and neural network predictive control algorithm on vehicle body height control based on the Simulink platform.The results show that PID control and neural network predictive control response fast,and the steady-state error is small when there is no interference,but the control effect is poor under interference,and it is unable to accurately track the target body height;Fuzzy control has a slow response speed,and the steady-state error is large when there is no interference,but control effect is good under interference,as vehicle body height has a small fluctuations and the target body height tracking effect is good;Considering the integral part's elimination function of the steady-state error,introducing an integral part of error in fuzzy control input port to improve the fuzzy control.The results show that the improved fuzzy algorithm can well control the steady-state error,and can maintain the good anti-interference ability.Finally,the whole vehicle body height control model based on CarSim,AMES im and MTALB/Simulink joint platform is established.This paper defines four modes of vehicle body height and sets mode switching rules,and then designs the mode switching controller;A whole vehicle body height controller is designed based on improved fuzzy control algorithm,and then designs a variable duty cycle PWM signal controller;Finally,this paper simulates the whole vehicle body height control in quasi-static and dynamic condition,the results show that body height control effect of this improved fuzzy control algorithm is good,vehicle body height can accurately track the target body height both in quasi-static and dynamic conditions.In summary,this paper establishes a seven degrees of freedom vehicle dynamic model with hydraulically interconnected suspension and according to the multiple requirements of a SUV,a multi-objective optimization of key parameters of hydraulically interconnected suspension has been executed.On the basis of 1/4 vehicle model,this paper researches PID control's,fuzzy control's and neural network predictive control's effect on body height control,and then improves fuzzy control algorithm;Based on optimized parameters,the improved fuzzy algorithm and joint simulation platform,this paper realizes the whole vehicle body height control,and provides theoretical guidance for vehicle body height control used in the real vehicle.
Keywords/Search Tags:Hydraulically interconnected suspension, Multi-objective optimization, Control algorithm, Joint simulation, Vehicle body height control
PDF Full Text Request
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