Vehicle land navigating device

Claim 1

A vehicle land navigating device, adapted to measure and update vehicle heading by North-seeking and navigating, comprising: (a) means for sensing vehicle heading and for generating vehicle heading measuring and updating data, comprising: (1) a flip table, adapted to be rotated so as to sequence through a series of angular positions and drift measurements to find North; (2) means for rotating the flip table so as to sequence the flip table through the series of heading positions; (3) a gyroscope, of the dual-axis type, adapted to have a first degree of freedom defining a first generally horizontal sensitive axis for North-seeking by aligning the gyroscope generally horizontal sensitive axis orthogonal to the horizontal component of the Earth Rate, and a second degree of freedom defining a second generally vertical sensitive axis for navigating, offset from the first sensitive axis, the output from which represents the heading rate of change, which gyroscope is further adapted to be mounted on the flip table to rotate therewith and to be rotated thereby through a sequence of heading positions to seek North and calibrate the gyroscope parameters including the horizontal axis drift and vertical axis drift and the vertical axis scale factor; and (4) an inclinometer, adapted to be mounted on the flip table for movement therewith and to define the pitch or roll axis of the vehicle body depending on the flip table position; (b) a housing for supporting the heading sensing and data generating means, adapted to be strapped down to the vehicle; (c) means for sensing the speed of the vehicle for navigating in conjunction with the updated heading angles for the Northing coordinates generated by the vehicle speed times the cosine of the heading, and for Easting coordinates generated by the vehicle speed times the sine of the heading; (d) means for enabling entry of data including coordinates, latitude, and map information; and (e) means for computing vehicle heading data from the heading sensed and data generated in the heading sensing and data generating means, including the inclinometer, temperature of the gyroscope, and the angle of the flip table, and in the speed sensing means, and from information entered in the data entry enabling means by coordinating the integral of the heading rate of change with the initial heading found during North seeking.