Kinematic modeling of cable-driven parallel robots with unlimited rotational axis

在工业用机械手中，绕轴无休止地旋转是很普遍的。机械手，如铰接式机器人、Delta或SCARA机器人，提供围绕至少一个轴的无休止旋转，以任意改变被处理工件的方向。另一方面，对于能够进行这种操作的并联机械手来说，这是相当不常见的，但对于绳索驱动的并联机器人来说，这种能力还有待探索，这是非常罕见的。由于其固有的性质，这些系统提供了与其他运动学机械手相比的关键优点，这些机械手与绕任意轴无限旋转的组合将为绳索驱动的并联机器人在生产中带来新的应用。在本提案的准备工作中，首次记录了绳索驱动的绕一轴无限旋转的并联机器人的具体设计。然而，由于缺乏描述和指定这类机器人的方法，这种方法还没有推广到更广泛的应用领域。绕任意轴的无限制旋转可以通过被动运动链的方式来机械地描述，从而导致已经冗余的绳索驱动并联机器人的内部自由度增加。这种物理扩展的模型确实需要显著扩展的运动学规范，以捕捉所有运动链和电缆传动链的相互作用。这种描述方法尚未被探索，但对于研究绕任意轴无限转动的绳索驱动并联机器人的一般设计是必不可少的。在提出者的准备工作中，描述是基于结构方程的特定用途的扩展，这为所给例子提供了解决方案。然而，这种方法不可能推广到包括其他产生旋转的机械方法。在本项目的范围内，将探索缆索驱动并联机器人的建模和综合方法的扩展，通过该方法可以一致地将绕任意轴的无限旋转融入到现有的方法中。这项工作的目的是在运动学和几何特性的扩展描述的基础上，找到这类绳索驱动并联机器人的通用设计。除了理论描述，实验验证将表明，存在绕任意轴无限旋转的可实现设计。

Endless rotation about an axis is widespread among manipulators for industrial use. Manipulators, such as articulated robots, Delta, or SCARA robots, provide endless rotation about at least one axis to arbitrarily change the orientation of the workpiece handled. It is quite uncommon, on the other hand, for parallel manipulators to be capable of such operations, yet alone for cable-driven parallel robots for which this capability is yet to be explored. Due to their intrinsic properties, these systems offer key benefits over other kinematic manipulators, combination of which with an endless rotation about an arbitrary axis will beckon new applications for cable-driven parallel robots in production.The first record of a particular design of a cable-driven parallel robot with an endless rotation about one axis has been given in preparatory works to this proposal done by the proposer. However, generalization of this approach to a broader selection of applications is yet to be completed as methods for describing and specifying such robots are lacking existence.Endless rotation about an arbitrary axis may mechanically be described by means of a passive kinematic chain resulting in an increase in the number of internal degrees of freedom in the already redundant cable-driven parallel robots. This physically extended model indeed requires a significantly extended kinematic specification to capture the interaction of all kinematic chains and the cable drive trains. This method of specification has not been explored but is essential to the investigation of generalized designs of cable-driven parallel robots with an endless rotation about an arbitrary axis. In the proposer's preparatory work, the description is based on an application-specific extension of the structural equation, which provides a solution for the example given. However, it is not possible to generalize this approach such that it also covers other mechanical means of generating rotations.Within the scope of this project, extension of modeling and synthesizing methods of cable-driven parallel robots shall be explored, by means of which endless rotation about an arbitrary axis can be consistently integrated into such existing methods. The aim of this work is to find generalized designs for such cable-driven parallel robots types based on the extended description of the kinematic and geometric properties. Besides the theoretical description, experimental validation will show that there are implementable designs with an endless rotation about an arbitrary axis.