Soft Ankle-Foot Exoskeleton for Rehabilitation: A Systematic Review of Actuation, Sensing, Mechanical Design, and Control Strategy

Robot-assisted rehabilitation therapy has become a mainstream trend for the treatment of stroke patients. It can not only relieve physiotherapists from heavy physical duties, but also provide patients with effective ankle-foot rehabilitation and walking assistance. Soft ankle-foot exoskeletons have rapidly evolved in the last decade. This article presents a compressive review of soft ankle-foot exoskeletons in terms of robot actuation, wearable sensor, mechanical design, and control strategy. Representative commercial and laboratory ankle-foot exoskeletons are demonstrated. Special attention is paid to the emerging soft actuators, wearable sensing techniques, and human-in-the-loop and hierarchical control methods. Finally, essential challenges and possible future directions are also analyzed and highlighted in this paper, which can provide reliable guidance on the development of next-generation soft ankle-foot exoskeletons.