提出了一种应用于发动机电磁气门系统的改进LuGre摩擦模型,对传统的LuGre摩擦模型进行了修正,增加了加速度分部和非线性连续开关函数.改进的摩擦模型解决了传统LuGre模型应用在高速离散场合下容易发散的固有缺陷,同时不仅保留了传统LuGre摩擦模型对于预滑动区域滞环效应的描述能力,又增加了对于滑动区域滞环效应的预测能力.将混沌搜索和高斯变异算子融入传统人工鱼群算法中形成优化的人工鱼群算法(IAFSA),用来对改进的LuGre摩擦模型中的参数进行辨识.通过静态特性试验和动态摩擦试验验证了IAFSA算法的有效性.利用所建立的精确摩擦力数学模型预测了在不同频率和不同位移下的摩擦力,并与实测的摩擦力进行了对比,结果表明,改进的LuGre摩擦模型能够准确地模拟电磁气门系统的动态摩擦特性.所提出的建模和参数辨识方法也适用于其他具有摩擦的高速机械系统.%A new modified LuGre friction model is presented for electromagnetic valve actuator system. The modification to the traditional LuGre friction model is made by adding an acceleration-dependent part and a nonlinear continuous switch function. The proposed new friction model solves the implementation problems with the traditional LuGre model at high speeds. An improved artificial fish swarm algorithm (IAFSA) method which combines the chaotic search and Gauss mutation operator into traditional artificial fish swarm algorithm is used to identify the parameters in the proposed modified LuGre friction model. The steady state response experiments and dynamic friction experiments are implemented to validate the effectiveness of IAFSA algorithm. The comparisons between the measured dynamic friction forces and the ones simulated with the established mathematic friction model at different frequencies and magnitudes demonstrate that the proposed modified LuGre friction model can give accurate simulation about the dynamic friction characteristics existing in the electromagnetic valve actuator system. The presented modelling and parameter identification methods are applicable for many other high-speed mechanical systems with friction.
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