Autonomous velocity estimation and navigation

• US 7,248,967 B2
• Filed: 08/17/2004
• Issued: 07/24/2007
• Est. Priority Date: 08/18/2003
• Status: Active Grant

• Current Assignee: Saab AB
• Original Assignee: Saab AB
• Inventors: Hagstedt, Anders
• Primary Examiner(s): Barlow; John
• Assistant Examiner(s): KUNDU, SUJOY K
• Application Number:
  US10/919,305
• Publication Number:
  US 20050143949A1
• Time in Patent Office: 1,071 Days
• Field of Search: 702/95
• US Class Current: 701/220
• CPC Class Codes: G01C 21/1654 with electromagnetic compass
• CPC Class Codes: G01P 7/00 Measuring speed by integrating acceleration measuring travelled distance by double integration of acceleration G01C21/16

Abstract

Measurement of a spatial velocity vector in order to make determination of a geographical position possible. A spatial velocity meter includes an inertial measurement unit, a direction-sensing module and a velocity processor. The inertial measurement unit registers acceleration parameters and angular velocity parameters in three dimensions. The direction-sensing module registers a natural reference signal. The velocity processor receives the acceleration parameters, the angular velocity parameters and the natural reference signal, and based thereon, generates the spatial velocity vector.

Claims

1. A spatial velocity meter adapted to be mounted on a craft, the spatial velocity meter comprising:

an inertial measurement unit adapted to register acceleration parameters and angular velocity parameters in three dimensions;

a direction-sensing module adapted to register a natural reference signal; and

a velocity processor adapted to receive the acceleration parameters, receive the angular velocity parameters, receive the natural reference signal, and generate a velocity vector of the craft in relation to the earth based at least on the acceleration parameters, the angular velocity, the natural reference signal, and a main velocity component of the craft being aligned with a longitudinal axis of the craft.

2. The spatial velocity meter according to claim 1, wherein the direction-sensing module comprises a magnetic measurement unit which is adapted to register a field vector of the terrestrial magnetic field to represent the natural reference signal, and the velocity processor is adapted to receive the field vector and determine the velocity vector on further basis of the field vector.

3. The spatial velocity meter according to claim 1, wherein the spatial velocity meter is adapted to register a spatial velocity of the craft, and the velocity processor is adapted to implement an estimation procedure, which in turn is adapted to derive the velocity vector based on a relationship between three dimensional forces and three dimensional angular velocities in respect of an axis being parallel to a longitudinal body axis of the craft.

4. The spatial velocity meter according to claim 1, further comprising:

a plumb-bob module adapted to receive the acceleration parameters and in response thereto produce a set of initial attitude parameters.

5. The spatial velocity meter according to claim 4, further comprising:

an attitude updating module adapted to receive the set of initial attitude parameters, receive the angular velocity parameters and based thereon produce a set of updated attitude parameters.

6. The spatial velocity meter according to claim 5, further comprising:

an error estimation module adapted to receive the set of updated attitude parameters, receive the acceleration parameters, receive the angular velocity parameters, and based thereon produce a craft velocity and at least one adjusted attitude angle.

7. The spatial velocity meter according to claim 6, further comprising:

a course calculation module adapted to receive the natural reference signal, receive the at least one adjusted attitude angle, and based thereon produce a course angle.

8. The spatial velocity meter according to claim 7, further comprising:

a velocity transform module adapted to receive the craft velocity, receive the at least one adjusted attitude angle, receive the course angle, and based thereon produce the velocity vector.

9. A navigation arrangement for determining a geographical position of a craft, the navigation arrangement comprising:

a spatial velocity meter adapted to be mounted on the craft and comprising an inertial measurement unit adapted to register acceleration parameters and angular velocity parameters in three dimensions, a direction-sensing module adapted to register a natural reference signal, and a velocity processor adapted to receive the acceleration parameters, receive the angular velocity parameters, receive the natural reference signal, and generate a velocity vector of the craft in relation to the earth based at least on the acceleration parameters, the angular velocity, the natural reference signal, and a main velocity component of the craft being aligned with a longitudinal axis of the craft; and

an integrator module adapted to receive an initial position coordinate, receive the velocity vector from the spatial velocity meter, and based thereon, generate an updated position coordinate.

10. A method for spatial velocity estimation of a craft, the method comprising:

registering acceleration parameters and angular velocity parameters of the craft in three dimensions;

registering a natural reference signal;

determining a velocity vector for the craft in relation to the earth based on the acceleration parameters, the angular velocity parameters, the natural reference signal, and a main velocity component of the craft being aligned with a longitudinal axis of the craft and

determining an updated position of the craft based on the natural reference signal and the velocity vector.

11. The method according to claim 10, wherein the registration of the natural reference signal involves registering a field vector of the terrestrial magnetic field;

and the determination of the velocity vector being based on the field vector.

12. The method according to claim 10, further comprising:

producing a set of initial attitude parameters in response to the acceleration parameters.

13. The method according to claim 12, further comprising:

producing a set of updated attitude parameters on basis of the set of initial attitude parameters and the angular velocity parameters.

14. The method according to claim 13, further comprising:

producing a craft velocity and at least one adjusted attitude angle on basis of the updated attitude parameters, the acceleration parameters, and the angular velocity parameters.

15. The method according to claim 14, further comprising:

calculating a course angle on basis of the natural reference signal and the at least one adjusted attitude angle.

16. The method according to claim 15, further comprising:

producing the velocity vector on further basis of the craft velocity, the at least one adjusted attitude angle, and the course angle.

17. A computer program product, comprising:

a computer readable medium; and

computer program instructions recorded on the computer readable medium and executable by a processor for carrying out the steps of

registering acceleration parameters and angular velocity parameters of a craft in three dimensions;

registering a natural reference signal;

determining a velocity vector for the craft in relation to the earth based on the acceleration parameters, the angular velocity parameters, the natural reference signal, and a main velocity component of the craft being aligned with a longitudinal axis of the craft; and

determining an updated position of the craft based on the natural reference signal and the velocity vector.

18. A navigation method for navigating a craft, the method comprising:

receiving an initial position coordinate for the craft;

registering acceleration parameters and angular velocity parameters in three dimensions for the craft;

estimating a spatial velocity for the craft in relation to the earth based on at least the acceleration and the angular velocity parameters; and

determining an updated position coordinate for the craft based on the initial position coordinate and an integration of the velocity vector, comprising estimating the spatial velocity by registering a natural reference signal and determining a velocity vector for the craft in relation to the earth based on the acceleration parameters, the angular velocity parameters, the natural reference signal, and a main velocity component of the craft being aligned with a longitudinal axis of the craft, and determining an updated position of the craft based on the natural reference signal and the velocity vector.

19. A computer program product, comprising:

a computer readable medium;

computer program instructions recorded on the computer readable medium and executable by a process for carrying out the steps of

receiving an initial position coordinate for the craft;

registering acceleration parameters and angular velocity parameters in three dimensions for the craft;

estimating a spatial velocity for the craft in relation to the earth based on at least the acceleration and the angular velocity parameters; and

determining an updated position coordinate for the craft based on the initial position coordinate and an integration of the velocity vector, comprising estimating the spatial velocity by registering a natural reference signal and determining a velocity vector for the craft in relation to the earth based on the acceleration parameters, the angular velocity parameters, the natural reference signal, and a main velocity component of the craft being aligned with a longitudinal axis of the craft, and determining an updated position of the craft based on the natural reference signal and the velocity vector.