Development of a Passive Modular Knee Mechanism for a Lower Limb Exoskeleton Robot and Its Effectiveness in the Workplace

Quasi-passive or passive mechanisms used for exoskeleton robots for load-carrying augmentation have been developed for reducing development cost, robot weight, and external energy consumption for augmentation. These mechanisms have been developed based on biomechanical analyses of specific motions; however, few mechanisms do not include mechanical elements, such as springs and dampers. In this paper, a movable instantaneous center of rotation (M-ICR) linkage mechanism developed for the knee in the lower extremity exoskeleton without using mechanical elements is presented. Wearability and augmentation functions are considered. Based on these functions, design optimization is achieved using the PIAnO tool. To verify the augmentation function, the Solidworks tool is used. To verify the effectiveness of the M-ICR knee mechanism, oxygen consumption and the vertical ground reaction force are measured while walking with a barbell (0 kg, 10 kg, 20 kg) and while standing with a grinder with and without wearing the exoskeleton robot.