Body Time-delay Damping Control Research Under Idle Speed Condition

The engine motivation is the underlying factor that caused vehicle vibration and affected the ride comfort under idle speed condition.It has been one of the main research direction the vehicle vibration reduction technology about how to block or weaken the engine vibration to the car body.Currently widely used engine mounting technology is the rubber mount or passive hydraulic mount,but they only can produce good results in certain frequency range and are unable to achieve vibration reduction in various driving conditions.In recent years,the active control technology which can adjust itself to adapt all kinds of working condition got rapid development.Aimed at this problem,this paper researched engine mounting technology that contained the active control technology.To achieve the effect of decreasing body system vibration through introduced the delay feedback active control technology into the engine mounting system.Its main contents as follow shows:(1)Vehicle idle system model is established.This paper’s study is about three models.They are the 1/4 and 1/2 vehicle idle speed model based on the state of body displacement,velocity and acceleration feedback,and the 1/2 vehicle idle speed model based on the state of engine displacement,velocity and acceleration feedback.(2)Stability analysis.Using the Routh Hurwitz stability criterion to determine the critical feedback gain and time delay system stability when lag is zero,applying the method of generalized Sturm rule and stability switch to further determine the delay system stability when lag isn’t zero,and got the corresponding stability and instability regions.The models in the paper all had stability interval and can make further analysis and research.(3)Parameter optimization.In view of the 1/4 vehicle time-delay feedback system model,established the optimized objective function that based on the body acceleration and engine acceleration.Aiming at the 1/2 vehicle body and engine time-delay feedback system model,established the optimized objective function that based on the body acceleration and pitching acceleration.This paper used particle swarm optimization(PSO)to optimize in the area of the stability and obtained the best time-delay control parameters of the every state feedback and made the vehicle vibration to get maximum inhibition.(4)Putting the optimal time-delay control parameters that under different state feedback into the corresponding model respectively,and comparing with no-delay feedback control system from frequency domain and time domain two aspects using MATLAB.In frequency domain,analysis studied the amplitude-frequency characteristics of time-delay system.In the time domain,in view of the 1/4 vehicle delay feedback system model,analysis compared the displacement,velocity and acceleration of car body.Aiming at the 1/2 vehicle body and engine time-delay feedback system model,analysis compared the displacement of the car body,engine displacement and the pitch acceleration.And comprehensive data and numeric analysis to measure control effect of different state feedback.By the results of simulation analysis shows,the system that included delay feedback control parameters has more obvious vibration damping effect compared with the system of no delay feedback control.