儿童安全座椅低频振动的仿真与优化设计

Simulation and Optimization Design of Child Safety Seats for Low Frequency Vibration

为降低儿童安全座椅低频振动对儿童乘坐舒适性的影响,建立六自由度汽车与安全座椅动力学模型。利用Matlab/Simulink模拟汽车在B级路面以20 m/s速度行驶的工况,分析车辆和座椅的振动情况。建立优化目标泛函,为保证结果的客观性,采用层次分析法(AHP)确定优化泛函的各项加权系数。采用拉丁超立方抽样进行被动减振优化,采用LQG线性二次调节器进行主动控制,用这两种方法来实现乘坐舒适性的优化。对比仿真结果可以得出被动控制对低频处的共振峰值衰减没有效果,而主动控制在4 Hz、7 Hz、10 Hz、12 Hz、15 Hz处与初始值产生的共振峰值相比有明显的衰减。两种实验得到的安全座椅垂直振动加速度均方根值表明,被动减振优化值比初始值降低了78.9%,主动控制情况下比初始值优化了60.5%。

In order to reduce the influence of low frequency vibration on the riding comfort of the child safety seats,adynamic model of the vehicle and the safety-seats with6degrees of freedom is established.The driving condition of thevehicle on the B-grade road at20m/s is simulated by means of Matlab/Simulink and the vibration condition of the vehicleand the safety seats is analyzed.The main optimization objective functional is built.To ensure the objectivity of the results,the analytic hierarchy process(AHP)is used to determine the weight coefficient of each term in the optimization functional.To obtain the better riding comfort,the Latin hypercube sampling test is applied to the passive vibration reduction and theLQR control is used to the active vibration control.The simulation results indicate that the active vibration control cansignificantly reduce the original resonant peak values at the frequencies of4Hz,7Hz,10Hz,12Hz and15Hz respectively.While the passive control doesn’t have this effect.The simulation of RMS of the vertical acceleration of the safety seatsshows that the optimal values of the passive reduction and the active control are reduced by78.9%and60.5%respectivelyin comparison with the initial values.