ABSTRACT
Knee braces are a kind of wearable lower extremity exoskeleton that can enhance people’s strength and provide desired locomotion. It is possible to use knee braces to assist elderly or disabled people in improving their mobility to solve many daily life problems, like going up and down stairs and over obstacles. A well-designed actuator is the key component for assistive knee braces. In this design, magnetorheological (MR) fluids are integrated into a motor to work with multiple functions as a motor, clutch, and brake in order to meet the requirements of normal human walking. To design multifunctional actuators, several design considerations including configurations, mechanical and electromagnetic designs, and the influence of a permanent magnet on MR fluids are discussed. Finite element models of the actuator are built and analyzed. Modeling of the actuator in different functions is presented. A prototype of the actuator is fabricated and each function is tested. Torque tracking in brake function of the actuator is investigated. The results show that the developed multifunctional actuator is promising for assistive knee braces.
