Dynamic torque analysis of a coaxial-actuated 3-DOF spherical parallel mechanism under varying working orientation
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https://doi.org/10.54939/1859-1043.j.mst.FMC.2026.117-124Keywords:
3-DOF spherical parallel mechanism; Simulation; Driving torque; Working orientation; Aerial platforms.Abstract
The coaxial-actuated three-degree-of-freedom (3-DOF) spherical parallel mechanism is a novel parallel robotic architecture that offers several advantages over conventional pan–tilt mechanisms and hexapods, including high structural stiffness, compact architecture, large payload capacity, low error accumulation, and high positioning accuracy. Furthermore, the coaxial arrangement of the mechanism limbs significantly reduces the installation space, improves structural symmetry, and facilitates integration into aerial platforms. However, the input driving torque varies considerably with the working orientation of the mechanism, directly affecting actuator selection, operational performance, and effective workspace utilization. This paper investigates the input driving torque characteristics of a coaxial-actuated 3-DOF spherical parallel mechanism under different working orientations. A virtual prototype of the mechanism is developed using Simscape Multibody and Simulink in MATLAB to evaluate the variation of the input driving torque. The working orientations are examined over an inclination angle ranging from 0° to 180° with an interval of 15°. Based on the simulation results, the distribution of the driving torque, the variation trend of the input driving torque with respect to the working orientation, and the orientations corresponding to the maximum torque demand are identified and analyzed. The results provide a comprehensive understanding of the relationship between working orientation and the input driving torque characteristics of the mechanism. The findings also establish a scientific basis for actuator selection, mechanical structure optimization, and control strategy development for spherical parallel mechanisms employed in applications requiring high positioning accuracy, high structural rigidity, and reliable operational stability.
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