Abstract
We illustrate how physical constraints of a biomechanical system can be taken into account when registering functional data from juggling trials. We define an idealized model of juggling, based on a periodic joint movement in a low-dimensional space and a periodic position vector (from an undefined joint to the finger tip) of approximately constant length along the observed trajectory. Our registration procedure first warps the cycles in the trial to each other and computes a periodic average, and then estimates the joint movement and the position vector of the abovementioned model.