Upper Limbs Extension and Flexion Angles Calculation and Visualization Using Two Wearable Inertial Measurement Units

Abstract

Human motion analysis is widely used in many fields such as physical rehabilitation, athlete training, health status diagnosis and many others. Range of motion (ROM) is an important parameter to evaluate limb’s performance during activity of daily. Goniometer is a device often used by physiotherapist to evaluate and analyse the ROM of individual’s limb movement. The objective of this works is to develop a system to measure ROM using multiple Inertial Measurement Units (IMU) and transfer data to host computer by using Bluetooth Low Energy (BLE). A software program was develop using Phyton to visualize the motion. In this works, Intel CurieNano board, a six degree of freedom IMU that consist of an accelerometer and a gyroscope was used to calculate the ROM using sensor fusion algorithm. The data from accelerometer and gyroscope were fused using the complementary filter to get the ROM. The motion data was acquired by IMU sensor was sent to a custom program developed in Python through BLE. This custom program displayed the acquired data and visualized the motion in 3D visual model. The IMU sensor was used to measure certain angles at 10°, 30°, 60° and 90° to test its accuracy. The results showed that the angle measurement using IMU sensors has correlation coefficient of 0.9967 where the reference method was goniometer.  The wrist flexion and extension angle have maximum error of 7.49° for flexion and minimum error of 1.14° for extension. The ROM measured using IMU sensor has maximum error of 3.57% compared to goniometer. It showed that the IMU’s ROM measurement method is as good as goniometer.

(Manuscript received: 21 March 2022 | Accepted: 6 May 2022 | Published: 8 July 2022)