Dynamics of the human head and torso during activities that require stable vision

Abstract

The dynamics of the head and torso during activities that require clear vision is a topic that has previously been studied. These studies have examined the relationships between the angular velocities of the head in pitch and yaw in activities that either require clear vision or do not. However, many of these studies have been performed in artificial settings and so have required the subject to perform uncommon activities. The present study attempts to overcome the limitations of studying head and torso dynamics in artificial settings and determine whether the relationships found in previous studies apply during more natural activities where subjects move freely and track moving targets. Equipment was developed to measure the movements of the head and torso. This equipment used several different sensors to measure both the rotational velocities and linear accelerations of all degrees of freedom for both the head and torso. Several experiments were conducted using this equipment with subjects who were required to catch a ball. The subjects in this experiment walked with no visual task portion, ran with no visual task, and also ran while trying to catch a ball. It was found that during these activities, the yaw of the head was stabilized when clear vision was required. The pitch of the head however, became less stable when completing activities that required clear vision. These findings are consistent with previous studies in the field of head and torso dynamics.