Method for Detecting a Working Area of an Autonomous Working Device, and a Working Device

• US 20170351265A1
• Filed: 11/17/2015
• Published: 12/07/2017
• Est. Priority Date: 12/16/2014
• Status: Active Grant

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Eagling, Thomas, Fincham, Steve
• Granted Patent: US 10,459,452 B2
• Time in Patent Office: Days
• CPC Class Codes: G05D 1/0265 using buried wires

Abstract

A method for detecting a position of a robotic vehicle relative to a boundary conductor surrounding a defined area includes the steps: providing an electrical current and a pseudo-random boundary signal, generating a current signal using the electrical current and the pseudo-random boundary signal, feeding the current signal into the boundary conductor to produce an alternating electromagnetic field, detecting magnetic field changes which are attributed to the alternating electromagnetic field, and generating a reception signal from the magnetic field changes, evaluating the reception signal with the generation of at least one reconstructed boundary signal, providing a reference signal identical to the pseudo-random boundary signal, carrying out a pattern recognition to determine a correlation value between the reference signal and the reconstructed boundary signal, determining the position inside/outside the defined area based on the determined correlation value. The electrical current and/or the pseudo-random boundary signal is/are amplitude-modulated using a modulation signal.

Claims

1. A method for identifying a position of an autonomous robotic vehicle relative to a boundary conductor surrounding a defined zone, the method comprising:

providing an electric current and a pseudo-random boundary signal;

generating a current signal based on the electric current and the pseudo-random boundary signal;

feeding the current signal to the boundary conductor to generate an alternating electromagnetic field;

detecting magnetic field variations that originate from the alternating electromagnetic field based on a voltage induced by the magnetic field variations, and generating a receive signal from the magnetic field variations;

evaluating the receive signal to generate at least one reconstructed boundary signal;

providing a reference signal that is substantially identical to the pseudo-random boundary signal;

executing a correlation-based pattern recognition to ascertain a correlation value between the reference signal and the reconstructed boundary signal; and

determining the position of the autonomous robotic vehicle at least one of inside the defined zone and outside the defined zone based on the ascertained correlation value,

wherein at least one of the electric current and the pseudo-random boundary signal is amplitude-modulated with a modulation signal, such that the current signal is amplitude-modulated.

2. The method as claimed in claim 1, wherein the modulation signal has at least one first signal portion that has a first amplitude, and a second signal portion that has a second amplitude, wherein the first amplitude differs from the second amplitude by a factor that is greater than 10.

3. The method as claimed in claim 2, wherein the first signal portion of the modulation signal is of a shorter duration than the second signal portion of the modulation signal by a factor of 5.

4. The method as claimed in claim 1, wherein at least one of the electric current the pseudo-random boundary signal is amplitude-modulated with a periodic modulation signal.

5. The method as claimed in claim 1, wherein the modulation signal corresponds at least partly to at least one of a step function, a rectangle function, a discontinuous, function, and a signal approximation of one of these functions.

6. The method as claimed in claim 1, in particular claim 5, wherein the modulation signal is time-dependent and is non-zero.

7. The method as claimed in claim 1, further comprising:

selecting the modulation signal in such a manner that the current signal provided in the boundary conductor is on average less than 1000 mA.

8. The method as claimed in claim 1, wherein the pseudo-random boundary signal is a binary signal having a quasi-random sequence of binary levels, and has a periodic bit pattern that is selected such that a length of a portion of the periodic bit pattern that is identical to a portion of an inverted bit pattern of equal length, is less than a predefined proportion with respect to the total length of the periodic bit pattern.

9. The method as claimed in claim 1, wherein the pseudo-random boundary signal is a Manchester-encoded binary signal having a quasi-random sequence of binary levels, and has a periodic 5-bit bit pattern in which a timing frequency is 5 kHz.

10. The method as claimed in claim 1, further comprising:

resetting the pseudo-random boundary signal after a time period that corresponds to a phase length of the modulation signal.

11. The method as claimed in claim 1, further comprising:

ascertaining a time correlation offset between the reference signal and the reconstructed boundary signal by (i) determining a plurality of correlation values for various time offsets, and (ii) determining the time correlation offset as the time offset for the correlation value that is greatest in amount.

12. The method as claimed in claim 1, further comprising:

triggering at least one function at the autonomous robotic based on the position of the autonomous robotic vehicle relative to the boundary conductor.

13. The method as claimed in claim 1, wherein movement of the autonomous robotic vehicle is only allowed inside the defined zone surrounded by the boundary conductor, the method further comprising:

effecting, in a case of the boundary conductor being reached by the autonomous robotic vehicle, a change of direction of the autonomous robotic vehicle.

14. The method as claimed in claim 1, further comprising:

executing a change of direction of the autonomous robotic vehicle in a direction of the boundary conductor in response to the position of the autonomous robotic vehicle relative to the boundary conductor is identified as being one of inside the defined zone and outside the defined zone.

18. The method as claimed in claim 12, the triggering further comprising:

triggering the at least one function at the mobile robot in response to the position of the autonomous robot vehicle indicating an exit from the defined zone.

15. An autonomous robotic vehicle that identifies its position relative to a boundary conductor surrounding a defined zone, the autonomous robotic vehicle comprising:

a detector unit configured to detect magnetic field variations, the magnetic field variations being generated by a fed-in current signal in the boundary conductor generated by use of a provided pseudo-random boundary signal, the detector unit being configured to generate a receive signal from the detected magnetic field variation;

a reference-signal generator configured to provide a reference signal having a bit pattern that is substantially identical to a bit pattern of the provided pseudo-random boundary signal; and

an evaluation unit configured to;

evaluate the receive signal generate a reconstructed boundary signal;

execute a correlation-based pattern recognition method to ascertain a correlation value between the reference signal and the reconstructed boundary signal; and

determine the position of the autonomous robotic vehicle relative to the boundary conductor at least one of inside the defined zone and outside the defined zone based on the ascertained correlation value.

16. A system comprising:

a boundary conductor surrounding a defined zone;

a signal generator configured to generate a current signal in the boundary conductor by use of a provided pseudo-random boundary signal; and

an autonomous robotic vehicle comprising;

a detector unit configured to detect magnetic field variations, the magnetic field variations being generated by the current signal in the boundary conductor, the detector unit being configured to generate a receive signal from the detected magnetic field variation;

a reference-signal generator configured to provide a reference signal having a bit pattern that is substantially identical to a bit pattern of the provided pseudo-random boundary signal; and

an evaluation unit configured to;

evaluate the receive signal generate a reconstructed boundary signal;

execute a correlation-based pattern recognition method to ascertain a correlation value between the reference signal and the reconstructed boundary signal; and

determine a position of the autonomous robotic vehicle relative to the boundary conductor at least one of inside the defined zone and outside the defined zone based on the ascertained correlation value.

17. The system as claimed in claim 16, wherein the signal generator is configured to provide the current signal in the boundary conductor that surrounds the defined zone based one the provided pseudo-random boundary signal and a provided electric current, wherein the current signal is amplitude-modulated.