电动轮系统中的轮毂电机会产生转矩波动，此转矩激励未经缓冲直接作用于轮 胎将会引起轮胎滑转率和纵向力波动等动力学问题． 为此，首先建立了电动轮纵扭耦合动 力学模型并分析电动轮的模态特征，提出用纵向加权加速度均方根值( W-ＲMS) 、滑转率 信噪比( SNＲ) 和负载转矩波动脉动率( DFＲ) 对电动轮纵向性能进行评价; 其次分析了系 统参数灵敏度，得出了评价指标受系统结构参数的影响规律:纵向加权加速度均方根值主 要受到车身质量和电机质量的影响，滑转率信噪比和负载转矩波动脉动率除受质量参数 影响外还取决于轮胎周向刚度和胎面刚度． 最后通过系统参数优化确定了使3 个指标改 善的参数取值，分析发现参数优化能够使各指标在对应模态下的最大值显著下降． 

 The in-wheel motor produces torque ripple，which exerts the wheel boss directly． It causes the longitudinal dynamic problems，such as fluctuation of tire slip rate and longitudinal force． Accordingly， the model characteristic of electric wheel is firstly analyzed and three indexes are proposed to evaluate the longitudinal performance of electric wheel． Secondly， the sensitivity of system parameter is analyzed，and the law is detected of longitudinal acceleration which is mainly affected by the mass of vehicle body and in-wheel motor． The error of slip ratio and fluctuation of load torque depend on mass parameters，circumferential rigidity of tire and tread rigidity． Finally， the parameter optimization determines the improvement of the parameter value of the three indexes and it is found that parameter optimization is able to cause each index to be radically reduced in maximum value under the condition of corresponding models．