Three dimensional knee kinematics are an interesting tool to gain a better understanding of this joint’s function and of the evolution of pathologies like osteoarthritis. Nowadays this evaluation takes places mostly in labs, using often expensive motion capture systems. A low cost ambulatory tool which could be used for routine clinical exams would be very beneficial. In order to produce such a tool, the use of inertial sensors seems to be a very interesting alternative to traditional systems.
The aim of this study is to evaluate the feasability of measuring 3D knee angles using two inertial motion units (IMU), each containing one 3D accelerometer and one 3D gyrometer. The methodology used to calculate these angles is divided into the three following steps : first, we have to compute the orientation of a single IMU and express it in a global coordinate system, using only the acceleration and angular rate data given by the IMU. Secondly, we have to compute the relative orientation of two IMUs, using a movement of circumduction of the leg for the alignment procedure. Finally, we have to establish a calibration method that allows us to follow as close as possible the recommandations of the International Society of Biomechnics for the description of knee joint angles.
The validation process allowed us to evaluate the precision of each step of the method, and to underline those that are key to its refinement. Indeed, the results are encouraging but their precision is not yet equal to that of the reference method.
Fauconnier, P. (Author),
Aissaoui (Supervisor) &
Hagemeister (Co-supervisor),
10 Oct 2013Student thesis: Master's thesis › Master in Engineering: Engineering