Process for determining the direction of the earth's magnetic field

• US 6,009,629 A
• Filed: 11/10/1997
• Issued: 01/04/2000
• Est. Priority Date: 03/13/1996
• Status: Expired due to Term

• Current Assignee: Leica Geosystems AG (Hexagon AB)
• Original Assignee: Leica Geosystems AG (Hexagon AB)
• Inventors: Weilenmann, Juerg, Gnepf, Silvio
• Primary Examiner(s): Fulton, Christopher W.
• Application Number:
  US08/945,797
• Time in Patent Office: 785 Days
• Field of Search: 33/357, 33/304, 33/313, 33/316, 33/319, 33/321, 33/355 R, 33/356, 702/92, 702/150
• US Class Current: 33/357
• CPC Class Codes: G01C 17/28 Electromagnetic compasses with north seeking magnetic elements and having electric pick-offs G01C17/26
• CPC Class Codes: G01V 3/40 specially adapted for measuring magnetic field characteristics of the earth

Abstract

A method for determining the direction of the Earth'"'"'s magnetic field, which may be interfered with by magnetic materials built into equipment and by electric currents, using an electronic magnetic compass which contains three magnetic field sensors and two devices for measuring inclination is provided. The electronic magnetic compass is arranged in N different spatial positions, in each of these N positions, the inclination sensor signals and the magnetic field sensor signals being measured and inclination values and magnetic field values being determined from these signals. On the basis of these inclination values and magnetic field values, the magnitude of the Earth'"'"'s magnetic field vector is determined using the vector equation

const=b.sub.g =b.sub.E sin(i)=g.sup.T L(b.sub.E)=g.sup.T m(b.sub.mes

-b_o)

with ##EQU1## N having to be at least equal to the number of parameters to be determined in the vector equation.

Claims

1. Method for determining the direction of the Earth'"'"'s magnetic field, which may be interfered with by magnetic materials built into equipment and by magnetic fields produced by electric currents, using an electronic magnetic compass which contains three magnetic field sensors and two devices for measuring inclination,

the electronic magnetic compass being arranged in N different spatial positions,

in each of these N positions, the signals from the devices for measuring inclination and the signals from the magnetic field sensors being measured and inclination values and magnetic field values being determined from these signals, and

on the basis of these inclination values and magnetic field values, the magnitude of the Earth'"'"'s magnetic field vector being calculated using the vector equation

View Dependent Claims (2, 3, 4, 5, 6, 7, 8)

2. Method according to claim 1, characterized in that one of the following scale definitions

b_g =const.;

m₁₁ =const.;

m₁₁ +m₂₂ +m₃₃ =const.;

m₁₁² +m₂₂² +m₃₃² =const.;

m₁₁² +m₁₂² + . . . +m₃₃² =const.;

det m=const.;

is selected.

3. Method according to claim 1, characterized in that Δ

M=0 is set if no soft magnetic spurious field is to be taken into account.

4. Method according to claim 1, characterized in that the magnetic field vector is determined using an optimization calculation if the number N of measurements in the various positions is greater than the number of available equations.

5. Method according to claim 1, characterized in that the magnitude of the Earth'"'"'s magnetic field vector is determined using a statistical optimization method on the basis of the determined inclination values and magnetic field values with additional use of the equation

6. Method according to claim 1, characterized in that inclination sensors are used as the devices for measuring inclination.

7. Method according to claim 1, characterized in that rotational speed sensors (gyros) are used as the devices for measuring inclination, the inclination angle being derived by integrating the rotational speed information.

8. Method according to claim 1, characterized in that encoders, with which angles are measured with respect to a reference point, are used as the devices for measuring inclination.