2012-098 – Velocity Updates in Personal Inertial Navigation

The invention refines the well-known idea of zero velocity updates for the purpose of personal inertial navigation. The velocity of the IMU is not precisely zero under most conditions, so the invention uses an innovative means to measure the small velocities involved and these measurements improve the performance of personal inertial navigation. The fundamental idea is that when the foot is in contact with the ground the actual point of zero velocity is a single point on the sole of the foot that moves from heel to toe in a somewhat predictable fashion. The IMU is not on the sole of the foot so it is never in a state of zero velocity. We measured the actual magnitude of this velocity to be on the order of 1 mm/sec for slowwalking. Such an error can cause tens of meters of error after a one hour period of inertial navigation. Meghan Hayes meghanh@andrew.cmu.edu 412-268-1241