Process for establishing the driving direction of a vehicle with an electronic compass

US4729172A · kind A · utility

Assignee

• Robert Bosch GmbH · DE

Inventors

• Gunther Alberter · Wendelstein, DE
• Harald Bauer · Ehningen, DE
• Gerhard Hettich · Roßtal, DE

Key dates

• Filing date: Nov 7, 1985
• Grant date: Mar 8, 1988
• Expiry date: Nov 7, 2005

Classification

• Technology area (CPC G): Physics
• CPC primary: G01C17/38
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

In a process for establishing the driving direction of a vehicle by an electronic compass fixedly mounted in the vehicle and which is provided with a magnetometer having a computerized evaluation circuit the local curve (O) of the earth field (He) is determined from five measuring points (M1 . . . M5) which are established by turning the vehicle and corresponding signals are stored. The parameters for the center point displacement (Hs), the shape (ellipse) and the turning (angle .alpha.) of the local curve (O) in the vector diagram (x,y) are calculated by the computer by means of an algorithm with five unknowns for the five measuring points and thereafter the direction of the earth field (He) is computed. Subsequently, the vehicle is oriented to a predetermined cardinal direction and a correction angle is determined from the difference of angles between the cardinal and north directions and the earth's magnetic field direction measured by the compass. In the subsequent measurements the correcting angle is then taken into consideration when establishing the driving direction (.phi.) from the local curve (O).