Shape Adaptive Modular Reconfigurable Systems

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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.