Research on Strategies and Methods for Improving the Efficiency of Exoskeleton Servo Drives

Abstract

Exoskeleton robots, as key assistive devices for human motion, hold broad application prospects in fields such as medical rehabilitation, industrial production, and military logistics. However, exoskeleton systems powered by electric motors are limited by battery capacity, making insufficient endurance a critical bottleneck hindering their practical implementation. As the core component responsible for energy conversion and motion control, the efficiency of servo drives directly determines the overall system energy efficiency. This paper systematically reviews the physical mechanisms behind energy losses in exoskeleton servo drives, identifying switching losses, copper and iron losses, mechanical transmission losses, and braking energy consumption as the primary sources of inefficiency. Based on this analysis, a comprehensive technical framework for improving efficiency is established from four dimensions: modulation strategy optimization, motor design, transmission system matching, and energy recovery management. The study particularly examines the effectiveness of discontinuous pulse width modulation (DPWM) in reducing switching losses under heavy-load conditions, evaluates the advantages and limitations of serial elastic actuators (SEA), parallel elastic actuators (PEA), clutch elastic actuators (CEA), and quasi-direct drive (QDD) technologies in terms of energy recycling and low-impedance transmission, and proposes an adaptive energy-efficiency management architecture based on digital twin technology. Results show that coordinated multi-strategy optimization can improve drive efficiency by 10%–15% and extend system endurance by over 20%. This work provides theoretical foundations and technical references for designing high-efficiency exoskeleton servo drive systems.