Gait Kinematics Intersegmental Coordination Law An Analytic Approach M.Sc. Thesis

The Law of Intersegmental Coordination is a well known kinematic law that correlates between the elevation angles of the segments of the lower-limb (thigh, shank, foot) during locomotion. This correlation reduces the degree of freedom of the angles to two and hence, the elevation angles covary along a plane in the angular space. The properties of the plane that constrains the time course of the elevation angles, have been extensively studied and measure of its orientation was correlated to gait velocity and energy expenditure. We have developed a mathematical model that explains what are the conditions on the time course of the elevation angles that must hold in order for the angular covariation to be planar. Moreover, an analytical formulation is proposed for both the orientation of the plane and the eccentricity of the looped shape that is produced on this plane. The normal to the plane and the eccentricity of the loop are given only in terms of amplitudes of the first harmonic of each of the segments’ elevation angels time course, and the phase shifts between these harmonics. Additionally, an intersegmental coordination was found for the upper-limb when considering the arm, forearm and the hand as its segments. The proposed model was able to predict both orientation of the plane for the lower-limb and the pattern of coordination for the upper limb with high accuracy. Finally, we have shown that the intersegmental coordination applies for the lower-limb while expressing different kinds of emotions during locomotion, such as, angry, fear, happiness and sadness. Pattern of coordination on the plane was found to be similar to that of neutral gait but with different plane characteristics. However, for the upper-limb pattern of coordination was found to be different from that of neutral gait and the model is not particulary useful in that case. We hypothesize that higher harmonics cannot be ignored while expressing emotion and their role in the encoding of emotion is yet to be discovered. An investigation of the ratio between the amplitudes of the first two harmonics of each of the segments of the lower limb during expression of emotion, reveals that this measure could be used as a classifier for emotions, and thus as a mechanism for emotion recognition in human gait.