Background: While efforts have been made to differentiate fall risk in older adults using wearable devices and clinical methodologies, technologies are still infancy. We applied a decision tree (DT) algorithm using inertial measurement unit (IMU) sensor data and clinical measurements to generate high performance classification models of fall risk of older adults. Objects: This study aims to develop a classification model of fall risk using IMU data and clinical measurements in older adults. Methods: Twenty-six older adults were assessed and categorized into high and low fall risk groups. IMU sensor data were obtained while walking from each group, and features were extracted to be used for a DT algorithm with the Gini index (DT1) and the Entropy index (DT2), which generated classification models to differentiate high and low fall risk groups. Model’s performance was compared and presented with accuracy, sensitivity, and specificity. Results: Accuracy, sensitivity and specificity were 77.8%, 80.0%, and 66.7%, respectively, for DT1; and 72.2%, 91.7%, and 33.3%, respectively, for DT2. Conclusion: Our results suggest that the fall risk classification using IMU sensor data obtained during gait has potentials to be developed for practical use. Different machine learning techniques involving larger data set should be warranted for future research and development.

Musculoskeletal disorders are generally caused by physical activity and job stress, lack of exercise, neck, shoulders, and back. In this paper, we were implemented using the IMU(Inertial Measurement Unit) sensor rehabilitation contents and measurements of the cervical range of motion that can help the rehabilitation of patients with musculoskeletal system. It was compared to the CROM method for verification of the IMU sensor data, the error rate was the result of less ±0.3󰔆. In other words, the results indicate that there is no problem to measure the cervical range of motion. So we were calculated the quaternion angle for each flexion, extension, and lateral flexion and extension, the contents for these was implemented. In addition, the implementation of a virtual reality-based contents using the Google cardboard was to show the possibility to replace existing high virtual reality contents.

본 논문에서는 소형 선박용 관성측정장치(Inertial Measurement Unit, IMU) 개발에 적합한 MEMS(Micro-Electro Mechanical System) 기반의 관성 센서 평가와 선정에 관하여 기술했다. 먼저, 오일러 공식에 기초한 관성 센서의 오차 모델과 잡음 모델을 정의하고, 앨런 분산(Allan Variance) 기법과 몬테카르로(Monte Carlo) 시뮬레이션 기법을 도입하여 관성 센서를 평가하였다. ADIS16405, SAR10Z, SAR100Grade100, LIS344ALH, ADXL103 등 다섯 가지 관성 센서에 대한 평가결과, ADIS16405의 자이로와 가속도계를 조합한 경우 오차가 가장 작게 나타났는데, 600 초 경과시 속도 오차의 표준편차가 약 160 m/s, 위치 오차의 표준편차가 약 35 km로 나타났다. 평가를 통해 ADIS16405 관성 센서가 IMU 구축에 최적임을 알았고, 이러한 오차 감소 방법에 대해서 참고문헌을 조사하여 검토하였다.