Sensitivity and Stability Analysis of a Kinematic Model for Human Joints (An Application to Human Ankle)

Biologic tissues tend to arrange themselves in order to achieve the optimal mechanical resistance (functional adaptation). In a previous work, a joint kinematic model has been proposed exploiting this concept. The joint capability to withstand an applied load has been hypothesized to be proportional to a measure of the joint congruence, which indicates how well mating surfaces fit together in a given joint configuration. The envelope of maximum congruence configurations defines a spatial trajectory along which the functional adaptation is satisfied and it is thus called functionally adapted trajectory. In this paper, the sensitivity of the kinematic model to the parameters defining the congruence measure is analyzed, together with the algorithm stability with respect to initial guess variations.