Patent ID: 9163933
Filing Date: 2015-10-20
Classification: A63F,G01B,G01C

Abstract:
1. A lightweight, wearable head tracking system comprising: a head worn structure; a head worn structure forward illuminating infra-red (IR) distance measuring apparatus, coupled to said head worn structure and configured to measure a forward distance to the ground in front of a person walking wearing said head worn structure; a head worn structure rearward illuminating infra-red distance measuring apparatus, coupled to said head worn structure; and configured to measure a rear distance to the ground behind a person walking wearing said head worn structure; an infra-red distance comparator configured to monitor changes of said forward distance and said rear distance and to generate a calibration signal representative of rotation of said head worn structure around a predetermined axis if, and only if, said changes of said forward distance and said rear distance are used to calculate corresponding forward head worn structure sensor rotation and rear head worn structure sensor rotation which are opposing each other; a gyro mounted to said head worn structure and generating a gyro output signal, which indicates a rotation rate of said head worn structure around said predetermined axis of rotation; a drift controller for selectively augmenting said gyro output signal when indicating gyro rotation rate about said predetermined axis of rotation when said calibration signal is representative of rotation, which is inconsistent with said gyro rotation rate; and a head tracking controller configured to utilize said gyro out signal after being augmented by said drift controller.