<![CDATA[Knee exoskeletons are proving to be highly effective tools for people with leg impairments, using external mechanical support to help their knees move more easily. However, to achieve an accurate trajectory tracking, nonlinearities and torque interaction due human–robot interaction can significantly affect the dynamic performance of the system. In this study, a fixed-time synergetic control (FTSC) strategy is proposed for the motion control of the knee-joint of an exoskeleton robot system. Furthermore, the performance of the proposed FTSC scheme is optimized using the Arctic Puffin Optimization (APO). A comparative study between the FTSC and conventional synergetic control (CSC) is carried out under step and sinusoidal motion-tracking scenarios. The results demonstrate the superior tracking performance of the proposed FTSC compared with the conventional CSC. The Integral Time of Absolute Error (IAE) performance index is selected as a quantitative measurement for improvements. The numerical data of the results reveal that the tracking error of the system controlled by the FTSC is reduced by 37.34% and 79.1% compared to that of the system controlled by the CSC for the unit step and sinusoidal signal inputs respectively. Furthermore, the FTSC demonstrated a substantial enhancement when a parameter variation was augmented in the simulation for the sinusoidal signal inputs.]]>
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