Kinematics, singularity, and workspace analysis of a balance rehabilitation parallel manipulator

Abstract Rehabilitation treatment is often labor-intensive and time-consuming, but it also lacks quantitative and objective assessment. With regard to the matter of balance rehabilitation machines, the continuous advancement of parallel robot technology provides new solutions for balance rehabilitation. However, these robots have inherent limitations, including a confined workspace, excessive height, a complex structure, and unstable movement due to singularity in workspace. Therefore, this study presents a new 3-2PUS double-triangular construction mechanism with six degrees of freedom for use in balance rehabilitation therapy. First, the forward and inverse kinematic models are established, and then the Newton–Raphson method is employed to resolve the forward kinematics. Subsequently, the velocity model is analyzed and its singular configuration is determined. Finally, the workspace of the 3-2PUS parallel mechanism is delineated, and the findings indicate that its structure is compact and that the workspace is free of singularities. This ensures that the rehabilitative devices will remain stable throughout the rehabilitation process, thus preventing any additional injuries that might otherwise result from unstable movement. To validate the study of the full parallel mechanism, a series of simulations is conducted using computational analysis software. Based on the analysis results, a prototype of a balance rehabilitation parallel manipulator is presented.