accelerometer machine learning 12 physical activity 9 wearable sensors 9 aging 8 gait analysis 8 older adults 8 rehabilitation 8 inertial measurement units 7 inertial sensor 7 kinematics 7 stroke 7 walking 7 IMU 6 calibration 6 cerebral palsy 6 clinical 6 deep learning 6 gait 6 signal processing 6 wearables 6 Parkinson's disease 5 accelerometers 5 accelerometry 5 adolescents 5 biomechanics 5 dynamic time warping 5 exercise 5 feature extraction 5 inertial measurement unit 5