IMU-based Smart Knee Pad for Walking Distance and Stride Count Measurement

Teng-Chia Wang1, Yan-Ping Chang1, Chun-Jui Chen1, Yun-Ju Lee1, Chia-Chun Lin1, Yung-Chih Chen2, Chun-Yao Wang3
1National Tsing Hua University, 2Yuan Ze University, 3Dept. CS, National Tsing Hua University


To calculate the knee angle, stride counts, and walking distance, we propose a system, iKneePad, fusing two 9-axis sensors with Bluetooth equipped on the thigh and shank segments. The changing rates of hip and knee angles are used to determine the beginning and the ending of a stride. The thigh length, shank length, hip angle, and knee angle are used to calculate the walking distance. The experimental results show that the accuracy of stride count is 100%, the absolute mean errors of knee angle are 2.99 degrees and 1.42 degrees for the maximum and minimum flexion angles, respectively. For walking distance, the mean error rates are \linebreak-2.40% and -2.26% for short (10m) and long (33m) distances, respectively. The proposed system also instantly provides feedback to users by showing on an Android smartphone when conducting rehabilitation or exercise with iKneePad.