NREX, an upper limb exoskeleton robot, was developed at the National Rehabilitation Center to assist in the upper limb movements of subjects with weak muscular strength and control ability of the upper limbs, such as those with hemiplegia. For the free movement of the shoulder of the existing NREX, three passive joints were added, which improved its wearability. For the flexion/extension movement and internal/external rotation movement of the shoulder of the robot, the ball lock pin is used to fix or rotate the passive joint. The force and torque between a human and a robot were measured and analyzed in a reaching movement for four targets using a six-axis force/torque sensor for 20 able-bodied subjects. The addition of two passive joints to allow the user to rotate the shoulder can confirm that the average force of the upper limb must be 31.6% less and the torque must be 48.9% less to perform the movement related to the axis of rotation.

Abstract
1. 서 론
2. NREX 기구 개선
3. 힘/토크 측정
    3.1. 실험 방법
    3.2. 실험 결과
4. 결 론
References

• 송준용(Department of Rehabilitative & Assistive Technology, National Rehabilitation Center) | Jun-Yong Song
• 이성훈(Department of Rehabilitative & Assistive Technology, National Rehabilitation Center) | Seong-Hoon Lee
• 송원경(Department of Rehabilitative & Assistive Technology, National Rehabilitation Center) | Won-Kyung Song Corresponding author