This paper presents the kinematic modeling of the human forearm rotation constructed with a spatial four-bar linkage. Especially, a circumduction of the distal ulna is modeled for a minimal displacement of the position of the hand during the forearm rotation from the supination to the pronation. To establish its model, four joint types of the four-bar linkage are, firstly, assigned with the reasonable grounds, and then the spatial linkage having the URUU (Universal-Revolute-Universal-Universal) joint type is proposed. Kinematic analysis is conducted to show the behavior of the distal radio-ulna as well as to evaluate the angular displacements of all the joints. From the simulation result, it is, finally, revealed that the URUU spatial linkage can be substituted for the URUR (Universal-Revolute-Universal-Revolute) spatial linkage by a kinematic constraint.

Abstract
1. 서 론
2. 관절 타입 선정
    2.1 근위 요척 관절
    2.2 원위 요척 관절
3. 기구학 해석
    3.1 모빌리티(Mobility)
    3.2 정기구학
    3.3 역기구학
4. 시뮬레이션
    4.1 제안된 전완 회전 모델
    4.2 근위 요골 관절의 기구학적 제한
5. 결 론
References

• 윤덕찬(Department of Electronic Systems Engineering, Hanyang University) | Dukchan Yoon
• 이 건(Department of Electronic Systems Engineering, Hanyang University) | Geon Lee
• 최영진(Department of Electrical and Electronic Engineering, Hanyang University) | Youngjin Choi Corresponding author