Impedance Control Strategies for Rehabilitation Safety in Wearable Assistive Exoskeletons: Comparative Analysis

Abstract

The integration of wearable assistive exoskeletons in rehabilitation protocols has introduced paradigm-shifting capabilities for motor recovery in neurologically impaired patients. Central to the clinical efficacy of these robotic systems is the control architecture governing the physical interaction between the human operator and the machine. This paper presents a comprehensive academic investigation into impedance control strategies, specifically evaluating their impact on rehabilitation safety and interactive compliance. As traditional rigid position control mechanisms frequently compromise patient safety by applying excessive interaction forces during human-robot misalignment, impedance control has emerged as a fundamental solution. By modulating the dynamic relationship between position errors and interaction forces, impedance controllers provide a compliant interface that accommodates human volition and physiological limitations. This study systematically compares fixed impedance control and variable impedance control paradigms through a rigorous methodological framework. The analysis encompasses kinematic tracking accuracy, dynamic force modulation, and stringent rehabilitation safety criteria, including the mitigation of spasticity-induced joint torque overloads. Through detailed simulated experimental evaluations, the findings demonstrate that adaptive and variable impedance control architectures significantly enhance patient safety by reducing peak transient forces while maintaining therapeutically adequate trajectory tracking. The paper concludes by discussing the clinical implications of these control strategies, addressing implementation challenges, and outlining future trajectories for the development of safe, intelligent, and highly compliant wearable assistive exoskeletons.