Dynamics Modeling and Performance Evaluation of a 3-Cylindrical–Prismatic–Spherical Orthogonal SDelta Robot Based on the Virtual-Work Principle

Abstract

Abstract. The SDelta is a six-degree-of-freedom (six-dof) parallel kinematics machine (PKM) designed for high-speed operations. It features a cylindrical–prismatic–spherical (CPS) joint structure. The orthogonal SDelta (OSD) is a variant thereof, with a cube-shaped base platform (BP) and orthogonal limbs. The OSD offers better workspace and dexterity characteristics than the SDelta and the classical six-dof PKM, namely theStewart platform. This article reports the inverse-dynamics model of the OSD mechanism using the virtual-work principle. Joint forces and torques are computed for a predefined trajectory of its moving platform (MP). Simulation results verify the accuracy and effectiveness of the proposed dynamics model. Additionally, the dynamics performance of the mechanism is evaluated based on its force-transmission characteristics and three force-sensitivity indices defined for human–robot collaboration (HRC) across two types of workspace: translational and orientational. Comparative analysis with the Stewart platform indicates that the OSD mechanism exhibits high performance in terms of these indices, suggesting its potential for applications requiring safe interaction and external force measurement on the moving platform.