Journal of rehabilitation welfare engineering & assistive technology (재활복지공학회논문지)

Rehabilitation Engineering And Assistive Technology Society of Korea (한국재활복지공학회)
권호 표지

Design and Optimization of an Knee Joint of Fully-active Transfemoral Prosthesis for Stair Walking

계단 보행을 위한 능동형 대퇴의지 무릎 관절의 설계 및 최적화

  • 안형종 (인하대학교 기계공학과) ;
  • 이광희 (인하대학교 기계공학과) ;
  • 홍이 (인하대학교 기계공학과) ;
  • 이철희 (인하대학교 기계공학과)
  • Received : 2015.10.28
  • Accepted : 2016.02.05
  • Published : 2016.02.29
Download PDF
⟨ Previous Next ⟩

Abstract

In this study, a fully active transfemoral prothesis with a knee joint is designed considering stair walking conditions. Since the torque at the knee joint required for stair walking condition is relative high compared with the one in normal walking condition, the proposed design has high torque generating mechanism. Moreover, the transfemoral prothesis is designed in compact size to reduce its weight, which is related to comfortable fit and fatigue of patients. Flat type BLDC motor is used for simple and compact structure and various components are used to generate required torque with target working angle and speed. The weight reduction of structure is carried out using optimization method after the initial design process is complete. The optimization is conducted under the load conditions of stair walking. The optimized design is validated via finite element analysis and experiments. As a result, the weight is reduced using topology and shape optimization but maintaining the safety of structure. Also the space efficiency is improved due to its compact size.

본 논문은 계단 보행 조건에서 작동할 수 있는 능동형 대퇴의지를 설계하고 구조 최적화를 통해 경량화를 진행하는 것을 목적으로 한다. 계단 보행 시 무릎에 걸리는 토크는 일반 보행에 비해 크므로 능동형 상대적으로 큰 토크를 낼 수 있는 동력 시스템이 필요하다. 또한 의지의 무게는 사용자의 착용감과 피로감과 연관이 되므로 의지의 경량화 설계 또한 필수적이다. 계단 보행 시 필요한 토크를 만들어내고 경량화와 소형화 구조를 적용하기 위해 플랫형 BLDC 모터를 사용하였다. 다양한 감속 장치를 이용해 필요 토크를 생성하고 작동각도 및 속도를 만족할 수 있게 감속비를 선정하였다. 구조 및 구동부 설계가 완료된 후 최적화를 통해 구조 경량화를 수행하였다. 계단 보행 시 나타나는 하중 조건을 고려하여 최적화를 수행하였으며, 해석 및 실험을 통해 최적화된 구조의 안정성을 검증하였다. 결과적으로 구조물의 강성은 유지하면서 위상 최적화와 형상 최적화를 통하여 무게를 감량하였으며, 공간 효율이 좋아졌다.

Keywords

References

  1. Ministry of Employment and Labor of Korea, 2014 Statistics of Disabled, Report for Employment Development Institute of Korea, Report no. Statistic survey 2014-04, pp. 25-29, 2014.
  2. Ministry of Health and Welfare of Korea, 2011 Report of an actual condition on disability, Report no. 11-1352000-000568-12, pp. 127-130, 2011.
  3. F. Sup, H.A. Varol, J. Mitchell, T.J. Withrow and M. Goldfarb, "Self-Contained Powered Knee and Ankle Prosthesis: Initial Evaluation on a Transfemoral Amputee", IEEE 11th International Conference on Rehabillitation Robotics, Kyoto, Japan, pp. 638-644, 2009.
  4. F. Sup, H.A. Varol, and M. Goldfarb, "Upslope Walking With a Powered Knee and Ankle Prosthesis: Initial Results With an Amputee Subject", IEEE Transactions on Neural Systems and Rehabilitation Engineering, vol. 19, no. 1, pp. 71-78, 2011. https://doi.org/10.1109/TNSRE.2010.2087360
  5. M. Omasta, D. Palousk, T. Navrat and J. Rosicky, "Finite element analysis for the evaluation of the structural behaviour, of aprosthesis for trans-tibial amputees", Medical Engineering & Physics, vol. 34, no. 1, pp. 38-45, 2012. https://doi.org/10.1016/j.medengphy.2011.06.014
  6. H.A.M. Seelen, S. Anemaat, H.M.H. Janssen, and J.H.M. Deckers, "Effects of prosthesis alignment on pressure distribution at the stump/socket interface in transtibial amputees during unsupported stance and gait", Clinical Rehabilitation, vol. 17, no. 7, pp. 787-796, 2003. https://doi.org/10.1191/0269215503cr678oa
  7. M.S. Pinzur, W. Cox, J. Kaiser, T. Morris, A. Patwardhan, and L. Vrbos, "The effect of prosthetic alignment on relative limb loading in persons with transtibial amputation:a preliminary", Journal of Rehabilitation Research and Development, vol. 32, no. 4, pp. 373-378, 1995.
  8. M. Zhang, M. Lord, A.R. Turner-Smith, and V.C. Roberts, "Development of a non-linear finite element modeling of the below-knee prosthetic socket interface", Medical Engineering & Physics, vol. 17, no. 8, pp. 559-566, 1995. https://doi.org/10.1016/1350-4533(95)00002-5
  9. S. Au, M. Berniker, and H. Herr, "Powered ankle-foot prosthesis to assist level-ground and stair-descent gaits", Neural Networks, vol. 21, no. 4, pp. 654-666, 2008. https://doi.org/10.1016/j.neunet.2008.03.006
  10. B.E. Lawson, H.A. Varol, A. Huff, E. Erdemir, and M. Goldfarb, "Control of Stair Ascent and Descent With a Powered Transfemoral Prosthesis", IEEE Transaction on Neural Systems and Rehabilitation Engineering, vol. 21, no. 3, pp. 466-473, 2013. https://doi.org/10.1109/TNSRE.2012.2225640
  11. Z. Luo, N. Zhang, Y. Wang and W. Gao, "Topology optimization of structures using meshless density variable approximants", International Journal for Numerical. Methods in Engineering, vol. 93, no. 4, pp. 443-464, 2012.
  12. J. H. Bak, K. H. Lee, C. H. Lee, "Study on Advanced Knee Joint Linkage of Active Prosthesis Leg" Journal of Rehabilitation Welfare Engineering & Assistive Technology, vol. 6, no. 2, pp. 9-14, 2012.
  13. R. Riener, M. Rabuffetti, C. Frigo "Stair ascent and descent at different inclinations", Gait and Posture, vol. 15, no. 1 pp. 32-44, 2002. https://doi.org/10.1016/S0966-6362(01)00162-X
  14. A. Protopapadaki, W.I. Drechsler, M.C. Cramp, F.J. Coutts, and O.M. Scott, "Hip, knee, ankle kinematics and kinetics during stair ascent and descent in healthy young individuals", Clinical Biomechanics, vol. 22, no. 2, pp. 203-210, 2007. https://doi.org/10.1016/j.clinbiomech.2006.09.010