基于向量键合图法的3-PPR型平面并联机构动力学分析

Abstract

为提高平面并联机构动力学分析的效率及可靠性，提出了相应的向量键合图法。根据3-PPR型平面并联机构构件间的运动约束关系，将平面运动刚体、旋转铰及移动铰的向量键合图模型组合起来，建立了3PPR型平面并联机构向量键合图模型。针对该类机构构件间非线性几何约束所导致的微分因果环问题，提出了有效的解决方法，克服了其给机构自动建模与动力学分析所带来的代数困难。应用相应的算法，实现了3-PPR型平面并联机构计算机辅助动力学建模与分析。通过实际算例说明了所述方法的可靠性及有效性。 For improving the reliability and efficiency of the dynamic analysis for planar parallel mechanism, the corresponding vector bond graph procedure is proposed. From the moving constraint relations between components of 3-PPR planar parallel mechanism, the corresponding vector bond graph model of the mechanism is made by assembling the vector bond graph models of planar rigid body, revolute joint and translational joint. For the problem of differential causality loop brought by nonlinear geometric constraints between components of the mechanism, the corresponding effective method is proposed. As a result, the algebraic difficulty in the mechanism automatic modeling and analysis is overcome. By the corresponding algorithm, the computer aided dynamic modeling and analysis of 3-PPR parallel mechanism is realized. By a practical example system, the reliability and validity of the procedure proposed are illustrated.