Topological design and performance analysis of a single-loop two-degree-of-freedom parallel mechanism with dual-mode output

A two-degree-of-freedom (DOF) parallel mechanism (PM) with dual-mode output, based on a simple single-loop configuration, is proposed and analyzed. Without requiring changes in its topological structure, the PM achieves two distinct motion outputs, that is, one-translation-one-rotation (1T1R) and three-translation-one-rotation (3T1R), by alternately using different components as the moving platform, which enables distinct manufacturing processes. First, a topological analysis of the PM is conducted, calculating its topological characteristics such as the position and orientation characteristics, DOF, and coupling degree. Subsequently, following the kinematic modeling and analysis method based on topological characteristics, symbolic forward and inverse position solutions for the PM are derived. The excellent motion decoupling is verified using the position parameters obtained from the forward solution. The workspace of the PM is then determined, and its singularities are analyzed based on the Jacobian matrix derived from the inverse position solution. To effectively enhance the workspace, a differential evolution (DE) algorithm is employed to optimize the dimensional parameters of the PM, targeting the attainable workspace as the objective. Afterward, dynamic modeling of the PM is performed using the virtual work principle-based ordered single-open-chain method, and the variation curves of the two required driving forces are obtained. Finally, a conceptual design for applying this PM to the application scenario in electromechanical cabinet assembly is presented. This research extends the design concepts and methodologies for reconfigurable or multi-mode mechanisms.