以3-PRRR三自由度移动并联机构为例提出一种考虑杆件空间复合弹性变形(包括弯曲、拉伸和扭转变形)的过约束并联机构受力分析方法。提出并定义分支约束力螺旋系刚度矩阵,建立分支约束力螺旋系幅值与分支末端弹性变形之间的映射关系;然后结合动平台受力平衡方程推导得到了分支约束力螺旋系幅值的一般解析表达式,分析施加给动平台的约束力螺旋与运动副实际约束反力之间的内在联系,从而求解得到了驱动力和所有被动运动副的约束反力。基于ADAMS仿真软件提出了一种建立过约束并联机构受力仿真模型的方法,所建刚柔混合模型与理论模型完全一致,且仿真结果与理论计算结果的最大误差不超过2%,有效地验证了提出的过约束并联机构受力分析的正确性。
A method for force analysis of the overconstrained parallel mechanism(PM) is proposed considering the link's spatial composite elastic deformations, including bending, tensile, and torsional deformations. Stiffness matrix of the supporting limb's overconstraint wrenches is put forward and defined, and the mapping relation between the magnitudes of the constraint wrenches and the elastic deformations of the supporting limb's end is established. Incorporating the force balance equation of the moving platform, the general analytical expression for the solution of each supporting limb's constraint wrenches is derived. The internal relation between the constraint wrenches imposed on the moving platform and the actual reactions of the kinematic joints is analyzed, and the actuated forces/torques and reactions of all the passive kinematic joints are solved. Based on ADAMS simulation software, a method to set up the force simulation model of the overconstrained PM is put forward, the established rigid-flexible model is completely consistent with the theoretical model, and the error between the simulation result and the theoretical calculation result is less than 2%, which effectively verifies the correctness of the proposed method for force analysis of the overconstrained PM.