I. Introduction
Industrial robots have applications in many areas, such as manufacturing, monitoring, and transporting. Parallel robots are new generation robots that have the advantages of perfect structural stiffness, strong bearing capability, and high kinematic accuracy [1]. Research on parallel robots can be divided into two categories. The first of these is parallel mechanism analysis, which includes mechanism, dynamics, and path planning. Due to the high complexity of parallel robots, most researchers concentrate on the mechanism design and optimization. The other category is parallel mechanism synthesis, where innovative work relies on the designers' experience and inspiration. As a result, mechanism synthesis has become the hotspot of parallel robot research [2], with many scholars working to find a mechanism synthesis method with universal significance.