Assistive devices of human knee joint: A review

Knee dysfunction, such as knee osteoarthritis, meniscus injury, ligament injury, spinal cord injury and stroke, considerably impacts the normal living ability and mental health of these patients. Developing more effective knee assistive devices is in urgent need for effectively recovering their motion capabilities and improving their self-living activities. In this paper, we review and discuss the mechanical system design, sensing and control systems design, and performance evaluation of the main research advances in knee assistive devices. Firstly, in order to clearly illustrate and compare the mechanical system design, the mechanical system design is classified into four components to discuss: human attachment design, joint alignment design, actuation design and power transmission design. Then, the sensing and control systems design, which includes human biological signals based control systems, human–device interaction signals based control systems and device signals only based control systems, is compared and discussed. Furthermore, the performance evaluation methods and effectiveness of most of the knee assistive devices are reviewed. Finally, a discussion of the existing problems in the current studies and some recommendations for future research are presented.