Title: Design and control of an assistive exoskeleton with passive toe joint

Authors: Ali Taherifar; Afshin Shariat; Reza Khezrian; Ahmad Zibafar; Amir Reza Rashidi; Hossain Rostami; Gholamreza Vossoughi; Ali Selk Ghafari

Addresses: School of Mechanical Engineering, Sharif University of Technology, Tehran, 14588-89694, Iran ' School of Mechanical Engineering, Sharif University of Technology, Tehran, 14588-89694, Iran ' School of Mechanical Engineering, Sharif University of Technology, Tehran, 14588-89694, Iran ' School of Mechanical Engineering, Sharif University of Technology, Tehran, 14588-89694, Iran ' School of Mechanical Engineering, Sharif University of Technology, Tehran, 14588-89694, Iran ' School of Mechanical Engineering, Sharif University of Technology, Tehran, 14588-89694, Iran ' School of Mechanical Engineering, Sharif University of Technology, Tehran, 14588-89694, Iran ' School of Science and Engineering, Sharif University of Technology, International Campus, Kish Island, Iran

Abstract: Several exoskeletons with various configurations and degrees-of-freedoms (DOFs) have been introduced in the literature, but not many have addressed the optimal selection of the mechanism's DOFs. In the proposed system a semi-passive toe joint is introduced to achieve several advantages. The performance of the proposed novel passive toe joint is evaluated experimentally. In addition, the semi-passive abduction/adduction DOFs in the hip joint and eversion/inversion DOFs in ankle joint is proposed to facilitate turning while providing more comfort during normal walking. The effect of passive DoFs existence on the user comfortability is studied with the aid of three kinematic indices. In the proposed mechanism, a set of compact, low-backlash rotary series elastic actuators are designed and incorporated to actuate the joints. A novel torque control is also introduced and evaluated experimentally. Results show good performance of the robot in zero-force control and impedance control during swing phase of motion.

Keywords: lower limb exoskeleton; passive toe joint; kinematic indices; human-robot interaction; zero-force control; assistive robot; rehabilitation; impedance control; series elastic actuator.

DOI: 10.1504/IJMA.2018.094485

International Journal of Mechatronics and Automation, 2018 Vol.6 No.2/3, pp.83 - 93

Available online: 26 Aug 2018 *

Full-text access for editors Access for subscribers Purchase this article Comment on this article