Full wireless goniometer design with activity recognition for upper and lower limb

Abstract

People must move using their lower and upper extremities to complete their work. Depending on these extremities' using frequency or different effects such as age, genetics, and body weight, the extremities' ability may decrease. The joints' range of motion(ROM) is measured to evaluate this decrease. Different systems, such as conventional goniometers, mobile phone applications, and sensor-based systems, can measure the ROM value. Still, it can be challenging to measure this parameter in different situations, such as training, moving activities, etc. The partial wireless goniometer and a companion 3D visualization and control GUI were developed in our previous study. However, it was difficult to mount it on the limbs at a distance, or it was impossible to use it for both legs to measure the hip angles. Therefore, this study presents a full wireless goniometer system that can simultaneously measure in real-time and show joint movements in a 3D model for the upper and lower extremities. The angle values required for the ROM were measured with two IMU sensors. Two ESP32s were used as microcontrollers in the system, and a fully wireless system was enabled by transferring data via ESP-NOW and Bluetooth. Thanks to ESP-NOW, the system has less latency compared to other protocols and can transmit data over longer distances. The developed system can also perform activity recognition which is not available in other goniometers. The measurements of the system were compared with a conventional goniometer, and their results were found to be completely correlated $\left({\rho }_c=1\right)$.