Research on Dynamics Modeling and Simulation of Constrained Metamorphic Mechanisms

This paper presents a method for establishing a unified dynamics model of constrained metamorphic mechanisms. Based on the equivalent resistance, the influences of geometric constraints and/or force constraints on metamorphism are discussed, and the kinematic characteristics of metamorphic joints are described and analyzed in detail. On this basis, the metamorphic configurations of augmented Assur groups can be classified into three types, including non-collision, internal collision and external collision configurations, and the configuration complete dynamics models of augmented Assur groups are established. Then, the dynamics models of active parts, Assur groups and augmented Assur groups are summarized into a unified mathematical framework, and the unified dynamics model of constrained metamorphic mechanisms can be obtained. Based on the research mentioned above, the initial conditions of all components and the motion law of the active parts are given. The motion laws of all components, the driving force/torque of the active parts and the constraint force/torque of the metamorphic joints can be obtained by iteration and solution based on the theory that velocity and acceleration are same in an extremely brief period. Taking the planar double-folded metamorphic mechanism and the metamorphic nipper swing mechanism as examples, the computer numerical analysis and dynamic simulation are carried out to verify the correctness and effectiveness of the proposed theory and method.