A new approach to accurate measurement of uniaxial joint angles based on a combination of accelerometers and gyroscopes

• Published in: IEEE transactions on biomedical engineering Vol. 52; no. 8; pp. 1478 - 1484
• Main Authors: Dejnabadi, H., Jolles, B.M., Aminian, K.
• Format: Journal Article
• Language: English
• Published: United States IEEE 01-08-2005; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Acceleration; Accelerometer and gyroscope; Accelerometers; Adult; Aged; Algorithm design and analysis; ambulatory system; biomechanics; Computer Simulation; Diagnosis, Computer-Assisted - instrumentation; Diagnosis, Computer-Assisted - methods; Female; gait analysis; Goniometers; Gyroscopes; Humans; joint angle; Joints; Knee; Knee Joint - physiology; Legged locomotion; Male; Middle Aged; Models, Biological; Motion measurement; Movement - physiology; Range of Motion, Articular - physiology; Reproducibility of Results; Sensitivity and Specificity; Studies; Transducers; Velocity measurement
• ISSN: 0018-9294; 1558-2531
• DOI: 10.1109/TBME.2005.851475

A new method of measuring joint angle using a combination of accelerometers and gyroscopes is presented. The method proposes a minimal sensor configuration with one sensor module mounted on each segment. The model is based on estimating the acceleration of the joint center of rotation by placing a pair of virtual sensors on the adjacent segments at the center of rotation. In the proposed technique, joint angles are found without the need for integration, so absolute angles can be obtained which are free from any source of drift. The model considers anatomical aspects and is personalized for each subject prior to each measurement. The method was validated by measuring knee flexion-extension angles of eight subjects, walking at three different speeds, and comparing the results with a reference motion measurement system. The results are very close to those of the reference system presenting very small errors (rms=1.3, mean=0.2, SD=1.1 deg) and excellent correlation coefficients (0.997). The algorithm is able to provide joint angles in real-time, and ready for use in gait analysis. Technically, the system is portable, easily mountable, and can be used for long term monitoring without hindrance to natural activities.