一种新型2-CPR/RRR平面移动并联机构的设计与分析

Design and analysis of a novel 2-CPR/RRR planar translational parallel mechanism

为了解决并联机构因结构耦合产生的强运动耦合性等问题,设计了一种含有恰约束运动链的新型2-CPR/RRR平面移动并联机构。基于螺旋理论研究了机构的自由度和输出特性,利用机构的几何关系建立了其位置矢量方程,推导出了不同形式主动输入情况下机构的运动数学模型;使用了Admas和Matlab分别对机构进行了运动学仿真,验证了理论分析的正确性;最后给出了该机构的一种3D打印机应用实例。研究结果表明:当以圆柱副的角位移作为主动输入时,速度雅可比矩阵为对角阵,因此机构具有无耦合运动特性;当以圆柱副的线性位移作为主动输入时,速度雅可比矩阵为单位阵,故机构具有完全各向同性的运动学特性。

In order to solve the problem of strong motion coupling caused by structural coupling of parallel mechanisms, a novel 2-CPR/RRR planar translational parallel mechanism with one pure constrained kinematic chain was proposed.Based on the screw theory, the degree of freedom and output motion characteristics of the mechanism were analyzed.The position vector equations were established in terms of the geometric conditions of the mechanism, and the kinematic mathematical mode were derived under the different input forms, rotary or linear.Kinematic simulation was performed by using Admas and Matlab, the kinematical curves of displacement, speed and acceleration were described.Finally, a new hybrid 3D printer was designed based on the parallel mechanism proposed.The experimental results show that when the rotary displacements of the cylindrical pair is selected as the actuated inputs, the Jacobian matrix is a diagonal one and the mechanism has the uncoupled kinematics. Especially, while the linear displacements of the pair is as the inputs, the Jacobian becomes an unit matrix and it shows fully-isotropic throughout its whole workspace.