Abstract
Metamorphic parallel mechanisms (MPMs) are a class of mechanisms that possess adaptability and reconfigurability to change permanent finite mobility based on topological structure change. Metamorphic parallel mechanisms keep the advantages of traditional parallel mechanisms in terms of high load-carrying capacity, good positioning accuracy and low inertia but with reconfiguration. MPMs are a new class of reconfigurable parallel mechanisms and have not been studied much. Therefore, this thesis is devoted to explore the fundamentals of mechanism theory on MPMs by focusing on two parts:(1) Systematic Methods of Synthesizing and Designing Metamorphic Parallel Mechanisms: A general strategy using reconfigurable joint to construct reconfigurable limbs has been proposed on synthesizing metamorphic parallel mechanisms and a general synthesis procedure has been provided based on screw theory. With two invented reconfigurable joints, many metamorphic parallel mechanisms have been obtained using the proposed method and their reconfiguration has been modelled in terms of geometric constraints. From the design point of view, the design parameters need to serve all phases of a metamorphic parallel mechanism. Thus a unified design performance representation is desired. Based on this, motion/force transmissibility is proposed to unifying the performance representation for optimal design of metamorphic parallel mechanisms considering all working phases and performance in each phase. Optimal design examples are demonstrated on some selected metamorphic parallel mechanisms.
(2) Unified Kinematics and Dynamics Modelling of Metamorphic Parallel Mechanisms: Since each of all reconfigured phases of a metamorphic parallel mechanism is equivalent to a traditional parallel mechanism and all phases with different mobility share the same mechanical structure, a unified strategy has been proposed by considering the reconfiguration of the joint and taking the reconfigured phases as special cases of the general configuration. Some selected metamorphic parallel mechanisms have been studied and their unified kinematics, workspace representation, and dynamics modelling are solved.
Thus this thesis provides basic synthesis, design, and modelling theory for metamorphic parallel mechanisms considering their reconfiguration and variable mobility.
| Date of Award | 2018 |
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| Original language | English |
| Awarding Institution |
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| Supervisor | Jian Dai (Supervisor) & Lakmal Seneviratne (Supervisor) |