Development of the Automatic Knee Joint Control System for a Knee-Ankle-Foot Orthosis Using an Electromechanical Clutch

전자-기계식 클러치를 이용한 장하지 보조기용 무릎관절 자동 제어 장치의 개발

  • 이기원 (연세대학교 보건과학대학 의공학과, 의공학연구소, 의용계측 및 재활공학 연구센터) ;
  • 강성재 (연세대학교 보건과학대학 의공학과, 의공학연구소, 의용계측 및 재활공학 연구센터) ;
  • 김영호 (연세대학교 보건과학대학 의공학과, 의공학연구소, 의용계측 및 재활공학 연구센터) ;
  • 조강희 (충남대학교 의과대학 재활의학과)
  • Published : 2001.08.01


A new knee-ankle-foot-orthosis(KAFO) which uses an automatically-controlled electromechanical wrap spring clutch for the knee joint was developed in the present study. It was found that the output voltage from the foot switches of the developed KAFO was proportionally increased with respect to the applied load. The output voltage from the infrared sensor also decreased as the knee flexion angle increased. The knee joint system for the new KAFO weighs only 780g lighter than any other commercially available developed system. In addition, the solenoid reduces the reaction time for the automatic control of the knee joint. The static torque of the clutch was measured for three persons, and it satisfied the normal knee extension moment during the pre-swing. Three-dimensional gait analyses for three different gait patterns (normal gait, locked-knee gait, controlled-knee gait) from five normal subjects were conducted. Controlled-knee gait showed the maximum knee flexion angle of 40.56$\pm9.55^{\circ}$ and the maximum knee flexion moment of 0.20$\pm$0.07Nm/kg at similar periods in the normal gait. Our KAFO system satisfies both stability during stance phase and free knee flexion during the swing phase at the proper period during the gait cycle. Therefore, our KAFO system would be very useful in various low extremity orthotic applications.


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