Abstract Limited rotational angles caused by the interference between the moving platform and kinematic chains of parallel mechanisms (PMs) has always been an issue. Hence a class of two-rotation and one-translation (2R1T) generalized parallel mechanisms (GPMs) with a high rotational capability, where the end effector is placed on the joint to avoid the problem, is presented. This type of GPM consists a multiple joint element and binary links connected by kinematic pairs. Hence the GPM can offer advantages in terms of a simple structure, high machining accuracy, and low machining cost. By combining the Grubler criterion and Euler's equation, the acceptable number of links and kinematic pairs is derived. Depending on the number synthesis results, joint arrangements are considered in each kinematic chain. Then the structure of kinematic chains is synthesized by virtual work. Examples of the 2R1T GPMs constructed by enumerated chains are shown. Finally, a kinematic analysis is performed on an example. The rotational performance and the singularity conditions are investigated. According to the above analyses, the rotational performance of 2R1T GPMs is excellent.

中文翻译：

---

新型2R1T广义大转角并联机构设计与分析

摘要 移动平台与并联机构（PMs）运动链之间的干涉引起的有限旋转角度一直是一个问题。因此，提出了一类具有高旋转能力的两转一平移 (2R1T) 广义并联机构 (GPM)，其中末端执行器放置在关节上以避免出现问题。这种类型的 GPM 由一个多关节元件和由运动对连接的二元连杆组成。因此，GPM 具有结构简单、加工精度高、加工成本低等优点。通过结合 Grubler 准则和 Euler 方程，可以导出可接受的连杆和运动对数。根据数量综合结果，在每个运动链中考虑关节安排。然后通过虚功合成运动链的结构。显示了由枚举链构建的 2R1T GPM 的示例。最后，对一个例子进行了运动学分析。研究了旋转性能和奇异条件。根据以上分析，2R1T GPM 的旋转性能非常好。