It is known that powertrain mount system plays an important role in vehicle design. For the steering wheel of a car shaking violently in the idle condition, its powertrain and suspension parameters were measured, and a 6-DOF math-ematical model of the powertrain mount system was established. The decoupling analysis showed that the coupling effect was serious in all the directions. Therefore, system optimal design was done. Firstly, the mount position was adjusted based on the impact center theory. Then, choosing the rigidity of the mount system and the mount inclination angle as the con-straint variables and the minimum decoupling of the 6 directions as the objective function, the optimal design was done us-ing the multi-objective optimization function“fgoalattain”of the Matlab. The results show that this method can realize bet-ter decoupling in all directions within a certain range of constraints and has high practical application values.%以某车型怠速运转时方向盘剧烈抖动为背景，测量动力总成和悬置参数，建立了动力总成悬置系统的6自由度数学模型，通过解耦计算，发现各个方向耦合比较严重，需要进行系统优化设计；应用撞击中心理论，对前后悬置位置进行调整，然后以悬置系统的刚度、悬置倾斜角度为约束变量，使用Matlab的多目标优化函数fgoalattain，以6个方向的耦合最小为目标函数进行优化设计，结果表明此方法能够在一定的约束范围内较好的实现各个方向的解耦，具有较高的实用价值。
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