System and method for navigation using two-way ultrasonic positioning

• US 20030142587A1
• Filed: 01/25/2002
• Published: 07/31/2003
• Est. Priority Date: 01/25/2002
• Status: Active Grant

• Current Assignee: Deere & Company
• Original Assignee: Navcom Technology, Inc. (Deere & Company)
• Inventors: Zeitzew, Michael A.
• Granted Patent: US 6,674,687 B2
• Time in Patent Office: Days
• US Class Current: 367/127
• CPC Class Codes: G01S 15/46 Indirect determination of position data
• CPC Class Codes: G01S 15/74 Systems using reradiation of acoustic waves, e.g. IFF, i.e. identification of friend or foe
• CPC Class Codes: G01S 2015/465 by Trilateration, i.e. two transducers determine separately the distance to a target, whereby with the knowledge of the baseline length, i.e. the distance between the transducers, the position data of the target is determined
• CPC Class Codes: G01S 7/52004 Means for monitoring or calibrating short-range imaging G01S7/5205
• CPC Class Codes: G01S 7/52006 with provision for compensating the effects of temperature
• CPC Class Codes: G05D 1/0221 involving a learning process
• CPC Class Codes: G05D 1/0255 using acoustic signals, e.g. ultra-sonic singals sonar systems designed for anti-collision purposes G01S15/93
• CPC Class Codes: G05D 1/027 comprising intertial navigation means, e.g. azimuth detector inertial navigation G01C21/16; inertial navigation combined with non-inertial navigation instruments G01C21/165
• CPC Class Codes: G05D 1/0272 comprising means for registering the travel distance, e.g. revolutions of wheels measuring distance traversed on the ground by vehicles, e.g. using odometers G01C22/00
• CPC Class Codes: G05D 1/0274 using mapping information stored in a memory device navigation using map-matching G01C21/30
• CPC Class Codes: G05D 1/028 using a RF signal

Abstract

A two-way ultrasonic positioning and navigation system and method involve a plurality of objects each capable of transmitting and receiving ultrasonic signals. A first object transmits an initiating ultrasonic signal and identifies a second object for responding to the initiating ultrasonic signal. The second object transmits a responding ultrasonic signal after a predetermined time delay from receiving the initiating ultrasonic signal. The first objectives the responding ultrasonic signal, and determines a distance between the first object and the second object based on a time period starting at the transmission of the initiating ultrasonic signal and ending at the reception of the responding ultrasonic signal, and on knowledge about the predetermined time delay and other known in advance time delays.

Claims

1. A method of operating a positioning system having a plurality of objects each configured to transmit and receive ultrasonic signals, comprising

transmitting an initiating ultrasonic signal from a first one of the plurality of objects, the initiating ultrasonic signal including a code identifying a second one of the plurality of objects for responding to the initiating ultrasonic signal;

transmitting a responding ultrasonic signal from the second one of the plurality of objects;

receiving the responding ultrasonic signal at the first one of the plurality of objects; and

determining a distance between the first one and the second one of the plurality of objects based on a time period starting at the transmission of the initiating ultrasonic signal and ending at the reception of the responding ultrasonic signal.

2. The method of claim 1 wherein the responding ultrasonic signal is transmitted after a predetermined time delay from a reception of the initiating ultrasonic signal at the second one of the plurality of objects.

3. The method of claim 2 wherein the responding ultrasonic signal is transmitted in a direction from which the initiating ultrasonic signal is received.

4. The method of claim 1 wherein the initiating ultrasonic signal is received among a plurality of ultrasonic signals and is selected out of the plurality of ultrasonic signals based on a calculated figure-of-merit for each of the plurality of ultrasonic signals.

5. The method of claim 1 wherein the responding ultrasonic signal is encoded to identify the object from which the responding ultrasonic signal is sent.

6. A method of operating a positioning system having a plurality of objects each configured to transmit and receive ultrasonic signals, comprising

transmitting an initiating ultrasonic signal from a first one of the plurality of objects, the initiating ultrasonic signal being accompanied by a radio frequency signal identifying a second one of the plurality of objects intended for receiving the initiating ultrasonic signal;

transmitting a responding ultrasonic signal from the second one of the plurality of object;

receiving the responding ultrasonic signal at first one of the plurality of object; and

determining a distance between the first one and the second one of the plurality of objects based on a time period starting at the transmission of said initiating ultrasonic signal and ending at the reception of said responding ultrasonic signal.

7. The method of claim 6 wherein the second one of the plurality of objects transmits the responding ultrasonic signal after a time delay from receiving the initiating ultrasonic signal that follows the radio frequency signal identifying the second one of the plurality of objects.

8. The method of claim 7, wherein the radio frequency signal accompanying the ultrasonic signal further include information for the time delay.

9. The method of claim 6 wherein the responding ultrasonic signal is transmitted in a direction from which the initiating ultrasonic signal is received.

10. The method of claim 6 wherein the responding ultrasonic signal is accompanied by a radio frequency signal identifying object from which the responding ultrasonic signal is sent.

11. An ultrasonic positioning system, comprising:

a plurality of objects each configured to transmit and receive ultrasonic signals, a number of the plurality of objects being greater than 2;

a first ultrasonic array positioned on a first one of the plurality of objects and configured to transmit initiating ultrasonic signals, each initiating ultrasonic signals including a code that identifies another one of the plurality of objects for responding to the initiating ultrasonic signal;

a second ultrasonic array positioned on a second one of the plurality of objects and configured to respond to the initiating ultrasonic signal coded to identify the second one of the plurality of objects by transmitting a responding ultrasonic signal; and

wherein the first ultrasonic array is configured to receive the responding ultrasonic signal, and is coupled to a timer that records a time period between the transmission of the initiating ultrasonic signal and reception of the responding ultrasonic signal.

12. The system of claim 11, wherein the second ultrasonic array include a plurality of ultrasonic transceivers facing different directions, and the responding ultrasonic signal is transmitted from a ultrasonic transceiver that received the initiating ultrasonic signal.

13. The system of claim 11, wherein the responding ultrasonic signal is encoded to identify the object from which the responding ultrasonic signal is sent.

14. The system of claim 11, wherein said second ultrasonic array positioned is programed to respond to the initiating ultrasonic signal identifying the second one of the plurality of objects by transmitting a responding ultrasonic signal after a predetermined time delay from receiving the initiating ultrasonic signal identifying the second one of the plurality of objects.

15. The system of claim 11, further comprising:

a processor positioned on the first one of the plurality of objects, and configured to calculate a distance between the first one and the second one of the plurality of objects based on the time period recorded by the timer and the speed of sound.

16. The system of claim 15, further comprising:

temperature and humidity sensors coupled to the processor.

17. The system of claim 15 wherein the first one of the plurality of objects is a mobile platform to be positioned and the second one of the plurality of objects is one of a plurality of beacons at fixed locations.

18. The system of claim 17 wherein the speed of sound is determined by inter-beacon ultrasonic measurements

25. The method of claim 18, further comprising:

iteratively improving the initial coordinates to obtain final coordinates for the beacons.

19. An ultrasonic positioning system, comprising:

a plurality of objects each configured to transmit and receive ultrasonic signals;

a first ultrasonic array positioned on a first one of the plurality of objects and configured to transmit initiating ultrasonic signals;

a radio transmitter positioned on the first one of the plurality of objects and configured to transmit a radio frequency signal with each initiating ultrasonic signal to identify another one of the plurality of objects intended for responding to the initiating ultrasonic signal;

a radio receiver positioned each of the plurality of objects;

a second ultrasonic array positioned on a second one of the plurality of objects and configured to respond to the initiating ultrasonic signal following a received radio frequency signal identifying the second one of the plurality of objects; and

wherein the first ultrasonic array is configured to receive the responding ultrasonic signal, and is coupled to a timer that records a time period between the transmission of the initiating ultrasonic signal and the reception of the responding ultrasonic signal.

20. The system of claim 19, further comprising a radio transmitter positioned the second one of the plurality of objects, and configured to transmit a radio frequency signal identifying the second object with the responding ultrasonic signal.

21. The system of claim 19 wherein the ultrasonic array on the second one of the plurality of objects transmits a responding ultrasonic signal after a time delay from receiving the initiating ultrasonic signal following a radio frequency signal identifying the second one of the plurality of objects.

22. The system of claim 21 wherein the radio frequency signal further includes information of the time delay.

23. The system of claim 19, wherein the first one of the plurality of objects is a mobile platform to be positioned and the second one of the plurality of objects is one of a plurality of beacons at fixed locations.

24. A method for calibrating a positioning system having a plurality of beacons, comprising

placing the beacons in or around a service volume according to a set of predetermined constraints;

determining a set of inter-beacon distances using inter-beacon 2-way ultrasonic measurements;

setting the origin of a coordinate frame at a first beacon;

setting one axis of the coordinate frame along the direction from the first beacon and a second beacon;

determining initial coordinates of the second beacon based on the distance between the first beacon and the second beacon;

determining initial coordinates of a third beacon based on the distances between the first beacon and the second beacon, between the second beacon and the third beacon, and between the third beacon and the first beacon, and based on the predetermined constraints.