Análise comparativa do torque em atuadores robóticos acionados por controle de 6 passos e controle por orientação de campo (FOC) aplicados à reabilitação de membros superiores

Abstract

Loss of upper-limb motor function, often resulting from stroke, is one of the main challenges in physical rehabilitation, and assistive robotics has emerged as an alternative for delivering more intensive, consistent, and measurable therapy. In this context, the control strategy adopted by the electric actuator directly affects the quality of the torque delivered to the patient. This work aims to compare the performance of two driving techniques for permanent magnet synchronous motors (PMSM) — six-step commutation and Field-Oriented Control (FOC) — with respect to torque generation, within the context of a robotic rehabilitation platform for the upper limbs inspired by the MIT-Manus. Both strategies were modeled and compared in a MATLAB/Simulink environment; in parallel, a custom outrunner PMSM (14 pole pairs) and a dedicated driver built around the STSPIN32G4 system-in-package were developed, and the experimentally identified electrical parameters of the physical motor were incorporated into the simulation model for a higher-fidelity validation. Results showed that, for an equivalent average torque (approximately 1.03 N.m), FOC produced a peak-to-peak torque ripple of 0.323 N.m (31.4 \%), about 4.8 times lower than that observed with six-step commutation (1.547 N.m, 150.1 \%), along with a superior speed dynamic response. It is concluded that FOC is the most suitable control strategy for rehabilitation applications requiring smooth and precise torque delivery, with physical experimental validation of the prototype remaining as the next development step.