Development of a body joint angle measurement system using IMU sensors

Abstract

This paper presents an approach for measuring and monitoring human body joint angles using inertial measurement unit (IMU) sensors. This type of monitoring is beneficial for therapists and physicians because it facilitates remote assessment of patient activities. In our approach, two IMUs are mounted on the upper leg and the lower leg to measure the Euler angles of each segment. The Euler angles are sent via Bluetooth protocols to a pc for calculating the knee joint angle. In our experiments, we utilized a motion capture system to accurately measure the knee joint angle and used this as the ground truth to assess the accuracy of the IMU system. The range of average error of the system across a variety of motion trials was 0.08 to 3.06 degrees. In summary, the accuracy of the IMU measurement system currently outperforms existing wearable systems such as conductive fiber optic sensors and flex-sensors.

Accelerometer based human joints' range of movement measurement

“…Method II for Joint Angle Measurement According to the study by [4,8], joint angles can be determined by subtracting absolute angles of the neighboring segments. Therefore to find the angle of a knee joint ( knee ), the angles for the absolute segments are initially computed, i.e.…”

“…This extensive interest is due to its great potential in a variety of applications and in recent times, has played a major role in many health related applications [3]. Research has shown that the ability to monitor human activities that include, human activity recognition and joint angle measurement [4] can effectively improve the quality of healthcare provided to patients [5].…”

“…An alternative method for measuring joint angles range of motion is with electrogoniometers. However, this approach requires a trained clinician to operate, it is time consuming to perform and is not sufficiently robust for daily clinical use [4,8].…”

“…Bakhshi et al [4] focused on measuring knee joint range of movement using two IMUs placed near the joint. Bennett et al [13] developed an algorithm to measure knee angles using two IMUs and artifitial neural networks.…”

Inertial Motion Capture Costume Design Study

“…Remote measurements of human subjects can improve the general health and the quality of life or limit the overall healthcare costs. The user-worn inertial measurement units (IMUs) has been proven to be suitable for unrestrained tracking of body segments’ orientations because they are small, light, affordable and completely self-contained [3,6,7,8,9]. …”