基于刚柔接触动力学的打结器虚拟打结方法研究

Virtual Knotting Method of Knotter Based on Rigid-flexible Contact Dynamics

摘要:

针对打结器结构改进或参数调整后在设计阶段难以评判优劣而增加制造投入成本的问题，以打结器能否打出绳结为评判准则，提出了一种基于刚柔接触动力学的打结器虚拟打结方法。该方法利用ADAMS的Bushing连接建立大变形柔性捆绳的动力学模型，通过对捆绳和刚性构件之间设置多接触约束和载荷施加，实现了完整的打结器虚拟打结仿真过程，研究了捆绳在拉力作用下成结的刚柔交互力学行为。通过对打结器样机的成结动作与虚拟打结的仿真结果进行对比分析，验证了捆绳动力学模型与刚柔接触动力学仿真模型的正确性，可作为评价设计优劣、保证打结器一次性制造成功的有效方法。利用该虚拟打结方法分析了打结嘴与夹绳盘动作时序差φ对打结器成结的影响，对判定打结器参数匹配后能否成结或成结优劣起到了直观验证作用。

Abstract:

Aiming at the problem of increasing investment cost of knotter production due to difficulty in evaluation of good or bad design after structure improvement or parameters adjustment of the knotter, a kind of virtual knotting method of knotter based on rigidflexible contact dynamics was presented according to the judgment rule of whether the knotter could tie a knot during design phase. The method used the Bushing connection tool under ADAMS to build up dynamic model of flexible rope with large deformation. A complete virtual knotting simulation process of the knotter was implemented by setting up multiple contact constraint between the rope and rigid component of the knotter and applying load to the rope. Rigidflexible interactive mechanical behaviors of tying a knot of the knotter were studied under the action of pulling force of the rope. The comparison analyses between knotting movements of the knotter prototype and virtual knotting results validated the correctness of dynamic model of the rope and simulation model of rigidflexible contact dynamics. It may be regarded as an effective method to evaluate good or bad design and guarantee disposable successful production of the knotter. The effects of the timing sequence difference value φ between the motion of knotting hook and the motion of ropeholding plate on knotting motion of the knotter were analyzed by using the proposed virtual knotting method, which can play visual validation role to judge whether the knotter can knot or tie a good and bad knot after parameters match of the knotter.