基于等效运动副化及运动副退化的公差分析法

针对公差不仅在数值上具有随机性，其所约束的几何特征在空间的位置姿态上也具有随机性的特点，提出了公差约束等效运动副化及运动副退化法。等效运动副化将公差约束的几何特征转化为被运动副控制的几何特征，该等效运动副本身是虚拟的具有多自由度的等效运动副，将公差约束的几何特征转化为被多自由度运动副控制的几何特征，装配体转变为一个无误差的开环机械臂，考虑到因装配工艺而产生的不同运动副自由度之间的相互制约的现象，采用运动副退化法去除冗余自由度，由此建立装配体公差分析模型，并将装配体公差模型分析的数值与加工装配体的实验检测值进行对比。

Tolerance Analysis Based on Equivalent Kinematic Pair and Degradation of Kinematic Pair

Subject to the random characteristics in deformations, position and value of the features which were constrained by tolerance, a method to analyze the stack-up of tolerance by deeming tolerance constrains to equivalent kinematic pair was proposed herein. Under the situation of equivalent kinematic pair, the features constrained by tolerance were transformed to the features constrained by n-DOF of kinematic pair and the assembly would be transformed to a robot arm, which connected by the rigid parts and without any errors. As the results of the assembly processes, the affections of interaction among different kinematic pairs were the emerging problems after transformed. To deal with that problems, the method of degradation for kinematic pair was proposed herein. Then the formula to analyze stack-up of tolerance was established based on the method of equivalent kinematic pair and degradation for kinematic pair. Finally, those methods were used to analyze a realistic assemble product, and compared the calculated values with the experimental results.