Abstract: A general 3-RPS parallel mechanism was proposed herein， whose moving platforms and fixed platforms were similar arbitrary triangles， and the axis of rotation pair was perpendicular to the connecting line between the center and the vertex of the fixed platform. Then mechanism， a new dish solar concentrator was designed. The closed vector method was used to obtain the inverse kinematic position solution of the mechanism. Then the screw theory was used to analyze the speed mapping relationship between the input and output of the mechanism， and the Jacobian matrix of the mechanism was established. Taking global dexterity， global stiffness and global bearing capacity as optimization indexes， the optimal design of structure parameters of the mechanism were obtained by genetic algorithm， and the radius of the fixed platform of the mechanism was determined. The distribution of each performance index in the reachable workspace of the mechanism before and after optimization was quantitatively compared and analyzed by means of the performance map method， and the static verification analyses of the mechanism before and after optimization were carried out by ANSYS software. Results show that the dexterity， stiffness and bearing capacity of the new type dish solar tracking platform are improved in varying degrees when the fixed platform radius is as 860 mm. 

Key words: solar tracking, parallel mechanism, performance evaluation index, dimensional optimization

摘要： 提出了一种通用3-RPS并联机构，其动平台、定平台为相似的任意三角形，且转动副轴线垂直于定平台中心与顶点的连线，基于该机构设计了一种新型碟式太阳能聚光器。采用封闭矢量法求得机构的运动学位置逆解，并以此为基础，运用螺旋理论分析机构输入与输出的速度映射关系，建立了机构的雅可比矩阵。以全域灵巧度、全域刚度性能及全域承载能力为优化指标，利用遗传算法对机构的结构参数进行优化设计，确定了定平台半径，借助性能图谱法定量地对比分析了优化前后各性能指标在可达工作空间内的分布情况，并采用ANSYS软件对优化前后机构进行静力学验证分析，结果表明：新型碟式太阳能跟踪装置的定平台半径为860 mm时，其灵巧度、刚度及承载能力等均有不同程度的提高。

关键词: 太阳能跟踪, 并联机构, 性能评价指标, 尺度优化