Method and apparatus for determining the position and orientation of a mobile transmitter

Patent metadata

Field	Value
Publication number	US-9625565-B2
Application number	US-201113809341-A
Country	US
Kind code	B2
Filing date	Jul 8, 2011
Priority date	Jul 9, 2010
Publication date	Apr 18, 2017
Grant date	Apr 18, 2017

Abstract

A method and an apparatus for determining the position and orientation of a mobile transmitter that has at least two linearly polarized antennas arranged at a predefined angle to one another. A plurality of receivers, which can be synchronized with the mobile transmitter and of which the position is known, each receive transmitter signals of predefined carrier frequency via a circularly polarized antenna. A field-theoretical model of the transmission path between the mobile transmitter and receivers is set up and defines the carrier phase measured values, the field-theoretical model is implemented in a Kalman filter, and the receiver signals are evaluated in terms of carrier phase measured values and/or time of arrival values. The position and orientation of the mobile transmitter are determined in the Kalman filter with use of the field-theoretical model and the carrier phase measured values and/or time of arrival values established from the receiver signals.

First claim

The invention claimed is:

1. A method for determining the position and orientation of a mobile transmitter, which has at least two linearly polarized antennas arranged at a predefined angle to one another, wherein a plurality of receivers, which can be synchronized with the mobile transmitter and of which the position is known, each receive transmitted signals of predefined carrier frequency via a circularly polarized antenna, said method comprising the following steps:
setting up a field-theoretical model for defining expected carrier phase measured values in which transmission paths between the at least two linearly polarized antennas of the mobile transmitter and the circularly polarized antennas of the plurality of receivers are modeled;
implementing the field-theoretical model in a Kalman filter;
evaluating the signals of the receivers in terms of carrier phase measured values or the carrier phase measured values and measured time of arrival values; and
determining the position and orientation of the mobile transmitter in the Kalman filter with use of the carrier phase measured values or the carrier phase measured values and the measured time of arrival values established from the signals of the receivers as measured quantities for the Kalman filter and the expected carrier phase measured values defined by the field theoretical model as expected values for the Kalman filter.

2. The method according to claim 1 , wherein setting up the field-theoretical model comprises the following steps:
determining an electromagnetic field generated by a transmitting antenna, wherein a known position and orientation of this transmitting antenna is predefined;
establishing a field strength generated by the transmitting antenna at the circularly polarized antenna of the respective receiver of known position in a vector field representation of the electromagnetic field;
determining complex currents induced in the circular polarized antenna of the respective receiver with use of components of the field strength in the vector field representation, wherein the circularly polarized antenna is modelled by two linear dipoles; and
defining the phase angle as the expected carrier phase measured value from the induced complex currents.

3. The method according to claim 2 , wherein, when determining the induced complex currents by means of the model of the circularly polarized antenna from two linear dipoles, a 90° shift of a phase shifter is taken into account.

4. The method according to claim 2 , wherein the electromagnetic field generated by a transmitting antenna is determined with use of field equations of a Hertzian dipole or by values measured in real terms of the field strength distribution of the transmitting antenna over a sphere, which are recorded in a table.

5. The method according to claim 1 , wherein rotational matrices in the form of cosine matrices or quaternions are used to convert a transmitter coordinate system and a receiver coordinate system into a reference coordinate system.

6. The method according to claim 1 , wherein the field-theoretical model for each transmitting antenna is set up in relation to each receiver.

7. The method according to claim 1 , wherein the transmitter and receiver are synchronized via use of the TDOA method including by means of an additional synchronization receiver of known position and/or by continuous estimation of deviations between clocks provided in the transmitter and receiver.

8. The method according to claim 1 , wherein the phase measured values and/or time of arrival values are corrected via a calibration value, which is generated with use of a reference transmitter of known orientation and position.

9. The method according to claim 1 , wherein the Kalman filter determines position coordinates and the orientation from the fed carrier phase measured values and time of arrival values of all receivers.

10. An apparatus for determining the position and orientation of a mobile transmitter, which has at least two linearly polarized antennas arranged at a predefined angle to one another, the apparatus comprising:
a plurality of receivers which can be synchronized with the mobile transmitter, and of which the position is known and which each have a circularly polarized antenna for receiving a transmitted signal of predetermined carrier frequency;
a Kalman filter, in which a field-theoretical model for defining expected carrier phase measured values is implemented, the field theoretical model modeling transmission paths between the at least two linearly polarized antennas of the mobile transmitter and the circularly polarized antennas of the plurality of receivers; and
an evaluation device for evaluating the receiver signals supplied by the receivers in terms of carrier phase measured values or carrier phase measured values and time of arrival values,
wherein the Kalman filter is designed to determine the position and orientation of the mobile transmitter with use of the carrier phase measured values or the carrier phased measure values and the measured time of arrival values established from the signals of the receivers as measured quantities for the Kalman filter and the expected carrier phase measured values defined by the field theoretical model as expected values for the Kalman filter.

11. The apparatus according to claim 10 , wherein the Kalman filter is an unscented Kalman filter.

12. The apparatus according to claim 10 , wherein at least three receivers are provided to form a localization system of the movable transmitter.

13. The apparatus according to claim 12 , wherein the at least three receivers are interconnected in a phase-locked manner.

Assignees

• Eidloth Andreas
• Thielecke Jörn
• Friederich-Alexander-Universität Erlangen-Nurnberg
• Fraunhofer Ges Forschung

Inventors

• Eidloth Andreas
• Thielecke Jörn

Classifications

• G01S5/0294 Primary

  Trajectory determination or predictive filtering, e.g. target tracking or Kalman filtering · CPC title

• G01S5/0247 Primary

  Determining attitude · CPC title