Copyright © 2006 The Institute of Electronics, Information and Communication Engineers
Regular Section -- Papers -- Biological Engineering |
Estimating Torque-Angle Relations of Human Elbow Joint in Isovelocity Flexion Movements
1 The author is with the Department of Biomedical Engineering, Faculty of Engineering, Osaka Institute of Technology, Osaka-shi, 535–8585 Japan. E-mail: aakzawa{at}bme.oit.ac.jp, 2 The author is with the Graduate School of Information Science and Technology, Osaka University, Suita-shi, 565–0871 Japan.
We investigated relations between torque and elbow joint angle for constant muscle activations in isovelocity flexion movements of the forearm in three normal subjects. The reference angular velocity was from 0 to 90°/s and the applied torque from 0 to 15% of maximum voluntary contraction. Integrated surface electromyograms (IEMGs) of six muscles, torque, angle and angular velocity of the elbow joint were measured. A mathematical model describing the relationship between these variables was constructed with an artificial neural network. We estimated elbow joint torque by presenting different elbow joint angles, constant IEMGs and constant angular velocity to the model. For elbow joint angles greater than 60°, the slope, which was defined as the rate of torque increase with respect to elbow joint angle, was negative. For elbow joint angles less than 50°, the slope changed from positive to negative when the angular velocity increased. This implied that the flexor muscle-elbow joint system could change from unstable to stable when the angular velocity increased.
Key Words: elbow joint, isovelocity flexion movements, electromyogram, artificial neural network
Manuscript received March 22, 2005. Manuscript revised January 6, 2006.