RANGING AND ANGLE OF ARRIVAL ANTENNA SYSTEM FOR A MOBILE ROBOT

• US 20170234961A1
• Filed: 02/16/2017
• Published: 08/17/2017
• Est. Priority Date: 02/16/2016
• Status: Active Grant

• Current Assignee: iRobot Corporation
• Original Assignee: iRobot Corporation
• Inventors: Lenser, Scott, Steltz, Erik, Shamlian, Steven, Doughty, Brian, Dube, Heath
• Granted Patent: US 10,459,063 B2
• Time in Patent Office: Days
• CPC Class Codes: G01S 1/68 Marker, boundary, call-sign, or like beacons transmitting signals not carrying directional information
• CPC Class Codes: G01S 3/023 Monitoring or calibrating
• CPC Class Codes: G01S 3/48 the waves arriving at the antennas being continuous or intermittent and the phase difference of signals derived therefrom being measured
• CPC Class Codes: G01S 5/021 Calibration, monitoring or correction G01S5/0252 takes precedence
• CPC Class Codes: G01S 5/10 Position of receiver fixed by co-ordinating a plurality of position lines defined by path-difference measurements , e.g. omega or decca systemsG01S5/12 takes precedence ; beacons and receivers cooperating therewith G01S1/306, G01S1/308
• CPC Class Codes: G01S 5/12 by co-ordinating position lines of different shape, e.g. hyperbolic, circular, elliptical or radial
• CPC Class Codes: H01Q 1/084 Pivotable antennas
• CPC Class Codes: H01Q 3/08 for varying two co-ordinates of the orientation
• CPC Class Codes: H01Q 9/30 with feed to end of elongated active element, e.g. unipole H01Q9/44 takes precedence
• CPC Class Codes: Y10S 901/01 Mobile robot

Abstract

A mobile robot includes a chassis, a shell moveably mounted on the chassis, and a cutting assembly mounted to the chassis. The mobile robot also includes a communication system that includes an antenna module disposed on a rear portion of the mobile robot. The antenna module includes a base assembly, and an antenna assembly mounted to the base assembly by a spring. The antenna assembly includes a ranging antenna, and at least three angle antennas arranged axisymmetrically about the ranging antenna, such that the ranging antenna and the three angle antennas define a tetrahedral geometry for determining an angle of arrival for one or more incident signals.

Claims

1. A mobile robot comprising:

a chassis;

a shell moveably mounted on the chassis;

a cutting assembly mounted to the chassis;

a communication system comprising;

an antenna module disposed on a rear portion of the mobile robot, the antenna module comprising;

a base assembly; and

an antenna assembly mounted to the base assembly by a spring, the antenna assembly comprising;

a ranging antenna; and

at least three angle antennas arranged axisymmetrically about the ranging antenna, such that the ranging antenna and the three angle antennas define a tetrahedral geometry for determining an angle of arrival for one or more incident signals.

2. The mobile robot of claim 1, wherein each pair of two of the angle antennas is separated by less than one half wavelength of the one or more incident signals.

3. The mobile robot of claim 1, wherein the ranging antenna and each of the at least three angle antenna is separated by less than one half wavelength of the one or more incident signals.

4. The mobile robot of claim 1, the top of the antenna assembly being positioned at a height of at least 400 mm.

5. The mobile robot of claim 1, wherein the spring is preloaded.

6. The mobile robot of claim 1, wherein incident signals have a frequency between 5925 MHz and 7250 MHz.

7. The mobile robot of claim 1, wherein the angle of arrival is calibrated using parameters determined from the ranging antenna and the three angle antennas.

8. A system comprising:

a network of devices; and

a mobile robot, comprising;

a chassis;

a shell moveably mounted on the chassis;

a cutting assembly mounted to the chassis;

a communication system comprising;

an antenna module disposed on a rear portion of the mobile robot, the antenna module comprising;

a base assembly; and

an antenna assembly mounted to the base assembly by a spring, the antenna assembly comprising;

 

a ranging antenna; and

 

at least three angle antennas arranged axisymmetrically about the ranging antenna, such that the ranging antenna and the three angle antennas define a tetrahedral geometry for determining an angle of arrival for one or more incident signals.

9. The system of claim 8, wherein the network of devices comprises at least one of a beacon, a set of beacons, a server, and a user device.

10. The system of claim 8, wherein incident signals have a frequency between 5925 MHz and 7250 MHz.

11. The system of claim 8, wherein each pair of two of the angle antennas is separated by less than one half wavelength of the one or more incident signals.

12. The system of claim 8, wherein the ranging antenna and each of the at least three angle antenna is separated by less than one half wavelength of the one or more incident signals.

13. A method for computing one or more calibration parameters associated with a pair of antennas disposed on a mobile robot, the method comprising:

receiving, by each of the pair of antennas for each of a plurality of locations of the pair of antennas relative to a transmitter, a wireless signal generated by the transmitter;

determining a phase difference of arrival (PDOA) of the wireless signal between the two antennas for each of the plurality of locations to obtain a set of PDOA values; and

computing the one or more calibration parameters based on the set of PDOA values.

14. The method of claim 13, wherein the plurality of locations of the pair of antenna comprise locations at different azimuth angles with respect to the transmitter.

15. The method of claim 14, wherein the one or more calibration parameters comprise a PDOA offset that is computed as a mean of the set of PDOA values.

16. The method of claim 14, wherein the one or more calibration parameters comprise a distance offset between the two antennas in the pair along a plane on which the antennas are disposed, the distance offset being computed based on an amplitude of a function that represents the set of PDOA values.

17. The method of claim 14, wherein the one or more calibration parameters comprise an angle offset between the two antennas in the pair along a plane on which the antennas are disposed, the angle offset being computed based on a phase of a function that represents the set of PDOA values.

18. The method of claim 13, wherein the plurality of locations of the one of the antenna in the pair of antenna comprise locations at different elevation angles with respect to the transmitter.

19. The method of claim 18, wherein the one or more calibration parameters comprise a vertical offset between the two antennas in the pair along a direction perpendicular to the plane on which the antennas are disposed.

20. The method of claim 13, further comprising adjusting the one or more calibration parameters to account for distortions introduced in the wireless signal by a channel between the transmitter and the pair of antennas.

21. The method of claim 20, wherein adjusting the one or more calibration parameters comprises:

accessing, a set of pre-computed correction parameters associated with the one or more calibration parameters; and

adjusting the one or more calibration parameters using the corresponding correction parameters.

22. The method of claim 20, wherein adjusting the one or more calibration parameters comprises:

accessing, a set of pre-computed correction parameters associated with the set of PDOA values;

adjusting the set of PDOA values using the corresponding correction parameters; and

computing the one or more calibration parameters based on the adjusted set of PDOA values.