Automatic north direction determn. for vehicles - using gyroscope and computer deriving transformation matrix from two accelerometer outputs

摘要

A device for automatically determining the direction of North in a vehicle using a gyroscope affected by the rotation of the earth derives the North deviation economically compared to complex conventional devices. The North deviation computer derives estimated values for vehicle to earth axes transformation matrix elements from the outputs of two accelerometers parallel and perpendicular to the vehicle longitudinal axis. The initial vehicle course in the earth axis system is derived from the matrix element extimates, the estimated values of vehicle revolution rate, the latitude, and the earth's rate of rotation. A dual axis gyroscope is used whose pitch axis is parallel to the vehicle vertical axis and whose input axes each have a torquer as in Parent Cert. No. 2741274.