Shape Adaptive Modular Reconfigurable Systems

本研究的目的是开发一种基于模块的方法，用于形状自适应模块化可重构系统（SAMRS）的设计、分析和运动规划，以满足整个系统（例如飞机变形机翼）的整体形状变化。我们提出的SAMRS是基于变几何桁架机构（VGTM）的原理，通过改变结构成员的长度来改变系统的形状和几何形状。为了减少执行机构的数量，同时满足运动和刚度的要求，将欠驱动并联机构的思想与过约束并联机构的概念相结合。我们的SAMRS的每个模块由主动构件和可锁定的被动构件组成，称为可变可锁定桁架（VLT）。我们的VLT模块是作为一个完整的系统开发的，其运动是确定的，并且在均衡和超静态之间经历拓扑重构。结果表明，对于给定的一组形状变化，通过求解不同被动构件在锁定作用下对应的过约束体系，可以预先确定所有桁架构件的长度。实际的形状变化是通过几个步骤来实现的，称为驱动序列，通过在所有被动成员之间切换锁定/解锁。在VLT思想的基础上，提出了三柱式三维SAMRS的研究方案。设计支柱包括三个要素。系统分解元素是开发一种方法，通过离散化和整合，找到需要改变的给定形状集所需的模块数量。模块设计元素侧重于使用枚举方法开发三维VLT模块。系统设计元素是为了系统的形成，并将开发一种搜索方法来寻找具有最少数量的执行器但又满足系统移动性和刚性的SAMRS。分析支柱还包括三个要素。动静力分析单元是开发新的方法，能够对可锁定被动构件产生的可变约束进行建模，并进行运动和静力分析。动力分析要素是建立模块和系统的动力学方程，并进行惯性方面的研究。振动分析单元是导出模块和系统的振动方程，解决结构振动问题。第三个支柱是运动规划，包括三个要素。首先是序列枚举，提出了一种新的枚举方法来确定所有可能的驱动序列。第二部分是序列选择，开发一种基于物理约束的选择算法，生成一组可行的驱动序列。最后一个要素是序列优化，即应用优化方法从一组可行的驱动序列中寻找最优解。

The objective of this research is to develop a module-based method for design, analysis and motion planning of a shape adaptive modular reconfigurable system (SAMRS) that is designed to satisfy the overall shape change of an entire system, for example, aircraft morphing wings. Our proposed SAMRS is based on the principle of variable geometry truss mechanism (VGTM) that changes the system shape and geometry by varying the lengths of structural members. In order to reduce the number of actuators yet still meeting the requirement of motion and stiffness, the idea of under-actuated parallel mechanism is applied to combine with the concept of over-constrained parallel mechanism. Each module of our SAMRS is composed of actuated members and lockable passive members, called variable lockable truss (VLT). Our VLT module is developed as a holonomic system whose motion is determinate and undergoes topological reconfiguration between isostatic and hyperstatic. As a result, for a given set of shape changes, all the truss member lengths can be pre-determined through solving the over-constrained systems corresponding to different passive members under locking. The actual shape change is realized through several steps, called actuation sequence, by switching locking/unlocking among all passive members. Based on the idea of VLT, this research program is put forward to develop a 3D SAMRS comprising three pillars. The design pillar includes three elements. The system decomposition element is to develop a method to find the number of modules, through discretization and consolidation, needed for a given set of shapes required to change. The module design element is focused on the development of 3D VLT modules with enumeration methods. The system design element is for system formation and a search method will be developed to find a SAMRS with a minimal number of actuators yet meeting system mobility and rigidity. The analysis pillar also includes three elements. The kinetostatic analysis element is to develop new methods that will be able to model the changeable constraints resulting from lockable passive members and carry out motion and static force analysis. The dynamic analysis element is to formulate module and system dynamic equations and carry out studies in respect to inertia. The vibration analysis element is to derive module and system vibration equations and address the problem of structural vibrations. The third pillar is motion planning and consists in three elements. The first element is sequence enumeration to develop a new enumeration method for the determination of all possible actuation sequences. The second element is sequence selection to develop a selection algorithm based on physical constraints to generate a set of feasible actuation sequences. The last element is sequence optimization to apply an optimization method to find an optimal solution from a set of feasible actuation sequences.