Phase in model-free perception of gait

Variations in human gaits are manifest in the timing of the many combined motions in the gait. In periodic systems, such as gait, timing reduces to phase. Therefore, in order to capture the important information in the timing patterns in a gait, one must consider phase. Gaits vary for several reasons, including different builds, moods of individuals, fatigue, and injury. We investigate the relationship between the model-free shape-of-motion phase analysis and a subjective description of gait, such as a normal gait versus a tired gait or a shuffle, by analyzing several gait image sequences that differ subjectively. A simple model based on a phasor representation of gait motion relates the pendulum-like motion of limbs to shape-of-motion features. Our ultimate goal is to develop a gait feature space that can be partitioned according to subjective perception of gait. Gait features that vary with subjective changes in gait lead in this direction.