FWOTM899 - Identification of Time-Varying Joint Impedances for the Application to Bionic Devices


The rotation of the human bones around the joints of the legs (hip, knee, ankle) is essential to perform daily tasks. The movements are regulated by the central nervous system (CNS), which changes the contraction of the muscles around a joint, resulting in a different joint stiffness. The action of the CNS is synchronized with the task at hand. For instance, when walking, the leg touching the ground is stiffer than when swinging forward.
A defective coordination of joint stiffness causes serious motor disabilities, which can be alleviated by prostheses (in the case of amputations) or orthoses (for external support to the leg), called bionic devices. The ultimate goal of bionic devices is to replicate the stiffness of a joint in concert with the human's motor plan. Therefore, a model of the changes of the joint stiffness during daily tasks is needed.
Currently, the modeling techniques used for bionic devices are approximative and only valid for extremely simple movements.
Thanks to the application of advanced time-varying modeling techniques, this research aims at obtaining more realistic models that are subject-specific and valid for multiple tasks. The results will be validated on relevant applications on bionic limbs, for which it is essential to have an accurate representation of the joint stiffness.
Dealing with the unpredictability of the humans, and complying with important requirements such as the safety and the comfort of the users, are among the expected challenges.


Rik Pintelon
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