Fundamentals for the application of eccentric joints in parallel kinematic machine tools

并联运动机床具有与串联运动机床相比的刚度和运动动力学方面的优点。但其应用范围仍然有限。寻找原因通常会产生运动精度的非有效提供以及工作空间不足。在这两种情况下，被动关节中使用的运动结构构成的基本弱点。一般来说，要求保护旋转接头轴线的交叉点。这简化了运动学模型，但也有缺点。作为原则问题，设计潜力受到很大限制。高关节刚度和大的枢转范围是相互矛盾的要求。接头的设计和制造受到折衷的约束。到目前为止，优化的解决方案导致昂贵的专用设计，这限制了其经济应用。该项目的目的是通过使用替代接头设计避免接头特定缺陷来增强PKM的应用范围。这种方法是放弃交叉关节轴的要求，导致偏心关节。因此，大的枢转范围和高的关节刚度不再是相互矛盾的要求。虽然偏心关节轴的想法并不是什么新鲜事，但它们在PKM中的使用仍然缺乏理论，设计以及应用特定方面的基础知识。在这个项目中，这些基础知识的开发和证明偏心联合作为单一的部分，以及应用到并联机床的实验研究。工作程序分为两部分。该项目的第一部分侧重于作为单个部件的偏心接头。在这方面，已经取得了可喜的成果。该项目的第二部分，现在有其重点的整体系统的PKM偏心关节。具体应用的基础知识将被开发和研究。这一方面涉及到控制安全和准确使用增强运动能力的具体要求，另一方面涉及到有关偏心接头可实现的整体系统性能增强的声明的推导。广泛的实验研究计划在这里的例子的六足FELIX的IWM德累斯顿。该试验台可确保在相同条件下对同一机器结构中的不同接头配置进行研究，从而获得最佳的结果可比性。

Parallel kinematic machine tools have advantages relating stiffness and motion dynamics com- pared to serial kinematic machines. However their application range is still limited. Looking for rea- sons often yields a non-efficient provision of motion accuracy as well as an insufficient workspace. In either case the passive joints used in the kinematic structure pose essential weak points. In general the intersection of the rotational joint axes is claimed. This simplifies the kinematic model but also has drawbacks. The design potentials are strongly limited, as a matter of principle. High joint stiffness and a large pivoting range are conflicting demands. The design and manufacturing of the joints is constrained to compromises. As of today optimized solutions lead to expensive special purpose designs, which restrict their economic application.Aim of the project is the enhancement of the application range of PKMs by avoiding joint specific drawbacks using an alternative joint design. The approach is to abandon the claim of intersecting joint axes, leading to eccentric joints. As a consequence a large pivoting range and a high joint stiffness are no longer conflicting demands. Though the idea of eccentric joint axes is not really new, their use in PKMs still lacks basics in theory, design as well as application specific aspects. In this project these basics are developed and proved by experimental investigations of eccentric joint as single parts as well as applied to a PKM. The working program is divided into two sections. The first section of the project focused on eccen- tric joints as single parts. Herein, promising results have been reached. The second section of the project now has its focus on the overall system of the PKM with eccentric joints. Application specific basics are to be developed and investigated. This relates on the one hand to control specific requirements for a safe and accurate usage of the enhanced motion capabilities and on the other hand to the derivation of statements about the enhancement of overall system properties realizable with eccentric joints. Extensive experimental investigations are planned here on the example of the hexapod FELIX of the IWM Dresden. This test bed ensures for investigations of different joint con- figurations in the same machine structure with identical conditions and thus for an optimal comparability of the results.