Framework for Knee Joint Movement Analysis with Inertial Sensors and Recursive Filters

Health and sports monitoring based on wireless low power and low range communication devices have been proposed by a number of commercial and scientific solutions. Low cost and small form devices allow data transfer and processing without cumbersome cabling. Inertial Measurement Units (IMU), that include an accelerometer, a gyroscope and sometimes may include one magnetometer, are used to determine body movement profile. Despite their inherent inaccuracy, these sensors are used for computing three-dimensional space object orientation. These computations are usually implemented with sensor fusion algorithms within devices that have enhanced computational capabilities. This paper presents a work that aims at estimating the limb and body trunk movements of a pedaling user/patient in a bicycle like device. The presented study has been undertaken within the Exobike project. The Exobike is a bicycle like exoskeleton where the lower limbs and the trunk of a user/patient are to be monitored using IMU data transferred through a radio frequency Bluetooth Low Energy protocol. This paper focuses on the use of IMU sensors and a type of recursive filters to estimate movement profile.