The study and optimization of kinematically redundant parallel manipulators

运动冗余并联机械臂的研究与优化

• 批准号: DDG-2015-00057
• 负责人: Boudreau, Roger
• 金额: $ 0.73万
• 依托单位: Université de Moncton
• 依托单位国家: 加拿大
• 项目类别: Discovery Development Grant
• 财政年份: 2016
• 资助国家: 加拿大
• 起止时间: 2016-01-01 至 2017-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=612457
• 关键词: study; optimization; kinematically; redundant; parallel

A parallel manipulator is a mechanism that consists of an end effector that is linked to its base by at least two chains. A well-known use is a flight simulator. These manipulators have certain advantages compared to serial manipulators, especially when it comes to rigidity and the ratio of the payload to the mass of the manipulator. However, the workspace is smaller and there exists configurations that are called singular in which the manipulator cannot resist to external forces or moments. Kinematic redundancy is obtained when extra links and joints are added to a chain. This enlarges the workspace, reduces or eliminates singularities and modifies the performance. This research program is an extension of our previous work and will focus on kinematically redundant parallel manipulators. The first objective of this research program is to study the effects of the number of degrees of redundancy on the performance of parallel manipulators. Different performance criteria will be studied while varying the number of degrees of redundancy. The second objective is to study the dynamic behavior of kinematically redundant parallel manipulators with different degrees of redundancy. In particular, the effect of redundancy on the performance of a manipulator that is following a trajectory with sharp corners or that passes near a singularity will be examined. The third objective is to perform the synthesis of kinematically redundant parallel manipulators. The synthesis problem requires the determination of the architectural parameters, for example the position of the attachment points, the length of the members or the dimensions of the end effector to satisfy certain specified criteria. This problem is complex since an infinite number of possible geometric parameters exist. Furthermore, when there is kinematic redundancy, there are an infinite number of possible joint values for a specified pose even when the architectural parameters are known. To perform the synthesis, an optimisation algorithm that evaluates a performance criterion for different combinations of architectural parameters and that changes the latter to improve the criterion is used. For example, if a prescribed workspace is desired, the optimisation modifies the architectural parameters to obtain a solution as close as possible to that desired. If it is desired to optimise another performance criterion at the same time, another optimisation is necessary to obtain the best combination of joint variables. A two-level optimisation will thus be necessary, a first to obtain the architectural parameters and a second within the first to optimise the performance. Parallel manipulators are used in certain industrial applications, in particular as flight simulators and as machine tools. Studies are necessary to determine if kinematic redundancy is beneficial. The results of this research will be beneficial to designers of parallel manipulators.

并联机械臂是一种由末端执行器组成的机构，末端执行器通过至少两条链与其基座相连。一个众所周知的用途是飞行模拟器。与串联机械臂相比，这些机械臂具有一定的优势，特别是在刚性和有效载荷与机械臂质量的比率方面。然而，工作空间较小，并且存在被称为奇异的构型，其中机械手无法抵抗外力或力矩。当在链上添加额外的连杆和关节时，可以获得运动冗余。这扩大了工作空间，减少或消除了奇异点，并修改了性能。本研究计划是我们先前工作的延伸，并将重点放在运动冗余并联机械臂上。本研究计划的第一个目标是研究冗余度数对并联机械臂性能的影响。在不同冗余度的情况下，将研究不同的性能标准。第二个目标是研究具有不同冗余度的运动冗余并联机器人的动力学行为。特别地，冗余对机械臂性能的影响是沿着一个轨迹与尖角或通过一个奇点附近将被检查。第三个目标是进行运动冗余并联机器人的综合。综合问题要求确定结构参数，例如附着点的位置、构件的长度或末端执行器的尺寸，以满足特定的标准。这个问题很复杂，因为存在无限多个可能的几何参数。此外，当存在运动冗余时，即使在已知结构参数的情况下，对于特定的姿态，也存在无限数量的可能的关节值。为了执行综合，使用了一种优化算法，该算法为不同的体系结构参数组合评估性能标准，并更改后者以改进标准。例如，如果需要指定的工作空间，则优化会修改体系结构参数，以获得尽可能接近所需的解决方案。如果希望同时优化另一个性能标准，则必须进行另一次优化以获得联合变量的最佳组合。因此，有必要进行两级优化，第一级优化是为了获得建筑参数，第二级优化是为了优化性能。并联机械手在某些工业应用中使用，特别是作为飞行模拟器和机床。研究是必要的，以确定是否运动学冗余是有益的。研究结果对并联机器人的设计具有一定的参考价值。