Range-finding and object-positioning systems and methods using same

• US 10,051,599 B2
• Filed: 01/20/2017
• Issued: 08/14/2018
• Est. Priority Date: 01/20/2016
• Status: Active Grant

• Current Assignee: ZeroKEY Inc.
• Original Assignee: ZeroKEY Inc.
• Inventors: Lowe, Matthew William, Dehghanian, Vahid
• Primary Examiner(s): Phu, Phuong
• Application Number:
  US15/411,935
• Publication Number:
  US 20170208565A1
• Time in Patent Office: 571 Days
• Field of Search: 375295, 375316, 375377, 342464, 4554566
• CPC Class Codes: G01S 1/74 Details
• CPC Class Codes: G01S 1/753 Signal details
• CPC Class Codes: G01S 1/80 using a comparison of transit time of synchronised signals transmitted from non-directional transducers or transducer systems spaced apart, i.e. path-difference systems
• CPC Class Codes: G01S 11/16 using difference in transit time between electrical and acoustic signals
• CPC Class Codes: G01S 5/30 Determining absolute distances from a plurality of spaced points of known location
• CPC Class Codes: H04L 1/0054 Maximum-likelihood or sequential decoding, e.g. Viterbi, Fano, ZJ algorithms
• CPC Class Codes: H04L 5/0048 Allocation of pilot signals, i.e. of signals known to the receiver
• CPC Class Codes: H04W 64/006 with additional information processing, e.g. for direction or speed determination

Abstract

A range-finding and/or object-positioning system comprises one or more target devices; one or more reference devices communicating with said one or more target devices via one or more wireless signal sets, each wireless signal set comprising at least a first-speed signal having a first transmission speed and a second-speed signal having a second transmission speed, and the first transmission speed being higher than the second transmission speed; and at least one processing unit performing actions for determining at least one distance between one target device and one reference device based on the time difference between the receiving time of the first-speed signal and the receiving time of the second-speed signal of the wireless signal set communicated between said reference and target devices.

Claims

1. An apparatus comprising:

at least one signal receiver for transmitting or receiving at least one set of signals to or from at least one location, each of the at least one set of signals comprising at least a Radio Frequency (RF) signal and an acoustic signal;

a temperature sensor; and

at least one processing unit coupled to the at least one signal receiver and the temperature sensor for;

calculating a first temperature-adjusted speed of sound by using the temperature measurement obtained by the temperature sensor;

calculating a calibrated speed of the acoustic signal by averaging the first speed of sound and at least one second temperature-adjusted speed of sound at the at least one location; and

determining the distance between the apparatus and each of the at least one location based on the time difference between the time of receiving the RF signal transmitted from said location and the time of receiving the acoustic signal transmitted from said location.

2. The apparatus of claim 1 wherein the at least one processing unit is configured for determining the distance between the apparatus and each of the at least one location comprises calculating said distance as:

3. The apparatus of claim 1 wherein the at least one signal receiver comprises at least a first signal receiver for receiving the RF signal, and a second signal receiver for receiving the acoustic signal.

4. The apparatus of claim 1 wherein the RF signal and the acoustic signal of each signal set are simultaneously transmitted from the first location.

5. The apparatus of claim 1 wherein at least one of the RF signal and the acoustic signal is encoded.

6. The apparatus of claim 1 wherein the at least one signal receiver is configured for receiving at least three signal sets transmitted from at least three locations;

and wherein the at least one processing unit is configured for, after determining the distance between the signal receiver and each of the at least three locations, determining the position of the signal receiver in a three-dimensional (3D) space with respect to the at least three locations to be any one of two possible positions, said two possible positions being calculated by using trilateration based on the distances between the apparatus and the at least three locations.

7. The apparatus of claim 6 wherein the at least one processing unit is further configured for determining the position of the apparatus from the two possible positions based on an accessibility of the apparatus to each of the two possible positions.

8. The apparatus of claim 1 wherein the at least one signal receiver is configured for receiving the signal sets transmitted from a plurality of locations;

and wherein the at least one processing unit is configured for, after determining the distance between the apparatus and each of the at least three locations, determining the location of the apparatus in a 3D space by using a Least Squares method based on the determined distances between the apparatus and the at least three locations, and the coordinates of each of the a plurality of locations in the 3D space.

9. The apparatus of claim 2 wherein the at least one processing unit comprises a Maximum Likelihood estimator for estimating n₀.

10. A positioning system comprising:

a plurality of reference devices having a coordinate system associated therewith, at least one of the plurality of reference devices located at an unknown position in said coordinate system;

one or more target devices at unknown positions in said coordinate system, said one or more target devices in communication with the plurality of reference devices via one or more wireless signal sets, each wireless signal set comprising at least a first-speed signal having a first transmission speed and a second-speed signal having a second transmission speed, and the first transmission speed being higher than the second transmission speed; and

at least one processing unit configured for;

calculating the position of the reference device whose position is unknown in said coordinate system based on the distances between the plurality of reference devices; and

for each target device,

determining the distance between the target device and each of the plurality of reference devices based on the time difference between the receiving time of the first-speed signal and the receiving time of the second-speed signal of the wireless signal set communicated between said reference and target devices; and

determining the position of said target device in said coordinate system based on the determined distances.

11. The positioning apparatus of claim 10 wherein the first-speed signal is a Radio Frequency (RF) signal, and the second-speed signal is an acoustic signal.

14. The positioning system of claim 10 wherein the at least one processing unit is further configured for measuring the distances between the plurality of reference devices.

15. The positioning system of claim 10 wherein said one or more wireless signal sets comprises a wireless signal set transmitted from one of the one or more target devices and received by the plurality of reference devices for determining the distance between the target device and each of the plurality of reference devices based on the time difference between the receiving time of the first-speed signal and the receiving time of the second-speed signal of the wireless signal set.

16. The positioning system of claim 10 wherein the distance between the target device and each reference device is determined as:

17. The positioning system of claim 10 wherein the first-speed signal and the second-speed signal of each signal set are simultaneously transmitted.

18. The positioning system of claim 10 wherein at least one of the first-speed signal and the second-speed signal is encoded.

19. The positioning system of claim 11 wherein each of at least one target device and at least one reference device further comprises a temperature sensor;

and wherein the at least one processing unit is further configured for;

calculating a first temperature-adjusted speed of sound at the at least one target device by using a temperature measurement obtained by the temperature sensor of the at least one target device;

calculating one or more second temperature-adjusted speeds of sound at the at least one reference device by using temperature measurements obtained by the temperature sensor of the at least one reference device; and

calculating a calibrated speed of the acoustic signal by averaging the first and the one or more second temperature-adjusted speeds of sound.

12. A positioning method comprising:

communicating one or more wireless signal sets between one or more target devices and a plurality of reference devices, said plurality of reference devices defining a coordinate system, said one or more target devices and at least one of the plurality of reference devices located at unknown positions in the coordinate system, each wireless signal set comprising at least a first-speed signal having a first transmission speed and a second-speed signal having a second transmission speed, and the first transmission speed being higher than the second transmission speed; and

calculating the position of the reference device whose position is unknown in the coordinate system based on the distances between the plurality of reference devices; and

for each target device,

determining the distance between the target device and each of the plurality of reference devices based on the time difference between the receiving time of the first-speed signal and the receiving time of the second-speed signal of the wireless signal set communicated between the target and reference devices; and

determining the position of said target device in the coordinate system based on the determined distances.

13. The positioning method of claim 12 wherein the first-speed signal is a Radio Frequency (RF) signal, and the second-speed signal is an acoustic signal.

20. The positioning method of claim 12 wherein said communicating the one or more wireless signal sets between the one or more target devices and the plurality of reference devices comprises:

transmitting one of said wireless signal sets from one of the one or more target devices; and

receiving said wireless signal set at the plurality of reference devices.

21. The positioning method of claim 13 further comprising:

calculating a first temperature-adjusted speed of sound at the at least one target device by using a temperature measurement obtained by the at least one target device;

calculating one or more second temperature-adjusted speeds of sound at the at least one reference device by using temperature measurements obtained by the at least one reference device; and

calculating a calibrated speed of the acoustic signal by averaging the first and the one or more second temperature-adjusted speeds of sound.