A Systematic Review of Sensing and Control Strategies of Wearable Active Ankle Exoskeletons/Exosuits, with Performance Assessment based on a Complexity Index

Many people worldwide suffer from motor impairments, with aging and stroke being two of the main causes, resulting in limited mobility for carrying out activities of daily living, reduced walking speed, increased metabolic consumption, and higher risk of falling. Exoskeletons are widely seen as a promising assistive technology for addressing these major challenges and mitigating the impacts of motor impairments. This review provides a comprehensive assessment of wearable active exoskeleton technologies, including their sensing, actuating, and control strategies, for elderly support in healthy aging applications. Specifically, we focus on actuators, sensors, and control strategies for active exoskeleton technologies applied to the ankle joint, as these play a critical role in human mobility assistance. By defining a complexity index that accounts for both mechanical and computational complexity of different exoskeleton solutions, we provide a comparative analysis of the landscape and conclude with a new perspective on future trends in soft, wearable, and modular ankle exoskeleton technologies.