Practical Structural Design Approach of Multiconfiguration Planar Single-Loop Metamorphic Mechanism with a Single Actuator

As a type of multiconfiguration mechanism that can operate in an under-actuated state, metamorphic mechanisms were proposed more than two decades ago and attracted significant interest. Studies on structural synthesis of metamorphic mechanisms tend to focus more on metamorphic techniques and the structural synthesis of source mechanisms for metamorphic mechanisms. By designing different constraint architectures of metamorphic joints, multistructures can be obtained from the same source metamorphic mechanism. To determine the constraint architectures of metamorphic joints and their different assembly combinations, a kinematic status matrix and a corresponding constraint status matrix are constructed based on the metamorphic cyclogram of a source mechanism. According to the equivalent resistance gradient model and the constraint status matrix, an equivalent resistance matrix for the metamorphic joints is proposed. A structural synthesis matrix of the metamorphic mechanism is then obtained from the equivalent resistance matrix by deducing the constraint form vectors of the metamorphic joints. Furthermore, a kinematic diagram synthesis of the source metamorphic mechanism of a planar single-loop metamorphic mechanism is proposed, which is based on only the 14 one- or zero-degrees-of-freedom linkage groups. The entire structural design method of a metamorphic mechanism is based on the structural synthesis matrix and is presented as a systematic process. Finally, the proposed structural design approach is illustrated by two examples to verify its feasibility and practicality. This study provides an effective method for designing a practical multi-mobility and multiconfiguration planar single-loop metamorphic mechanism with a single actuator.

Structure Synthesis of Multi-DOF Planar Metamorphic Mechanisms With a Single Driver

This paper approaches the type synthesis of multi-degree of freedom planar metamorphic mechanisms with a single driver in a systematic process. The process is facilitated by implementing a constraint status matrix and a equivalent resistance matrix as a method for identifying an appropriate structure of planar metamorphic mechanisms with a single driver. Multi-structures can be obtained from the same source metamorphic mechanism by designing different constraint architectures of metamorphic joints. To determine the constraint architectures of metamorphic joints and their different assembly combinations, the constraint status matrix is built based on the task-based metamorphic cyclogram of a source mechanism. According to the equivalent resistance gradient model and the constraint status matrix, an equivalent resistance matrix for the metamorphic joints is proposed. A structural synthesis matrix of the metamorphic mechanism is then obtained from the equivalent resistance matrix by deducing the constraint-form vectors of the metamorphic joints. Furthermore, an effective kinematic diagram synthesis of the source mechanism of the planar metamorphic mechanism is proposed which is based only on the 14 one or zero degree-of-freedom (DOF) linkage groups. The entire structural design method of a metamorphic mechanism is based on the structural synthesis matrix and given in steps. Finally, a proposed structural design approach is illustrated by two examples.

A holographic matrix representation of the metamorphic parallel mechanisms

Metamorphic mechanisms belong to the class of mechanisms that are able to change their configurations sequentially to meet different requirements. In this paper, a holographic matrix representation for describing the topological structure of metamorphic mechanisms was proposed. The matrix includes the adjacency matrix, incidence matrix, links attribute and kinematic pairs attribute. Then, the expanded holographic matrix is introduced, which includes driving link, frame link and the identifier of the configurations. Furthermore, a matrix representation of an original metamorphic mechanism is proposed, which has the ability to evolve into various sub-configurations. And evolutionary relationships between mechanisms in sub-configurations and the original metamorphic mechanism are determined distinctly. Examples are provided to demonstrate the validation of the method.