Abstract

Recently, walking assistance systems are receiving a great attention according to the increase of elderly population. To effectively assist human motions, such systems are required to generate precise and large assistive torques. Moreover, the assistive systems should be light and compact for the comfort and safety issues. In this paper we designed lower extremity assistive device with compact rotary series elastic actuators(cRSEAs) that are designed considering those factors. A worm gear is utilized to amplify the motor torque in the limited space. Also, to generate joint torque as desired, a torsional spring is installed between the motor and the human joint. The device generates large assistive torques by using worm gear, but the large friction introduced by the warm gear makes the controller design challenging. In this paper, a feedback control algorithm is utilized to compensate for such undesired friction. The proposed method is verified by experiments.