Object sensing using dynamic demodulation

Patent metadata

Field	Value
Publication number	US-9507049-B2
Application number	US-201314045985-A
Country	US
Kind code	B2
Filing date	Oct 4, 2013
Priority date	Oct 4, 2013
Publication date	Nov 29, 2016
Grant date	Nov 29, 2016

Abstract

An object detection method comprises transmitting a plurality of signals from a transmitter into a region; measuring a plurality of signals, each corresponding to a respective one of the plurality of the transmitted signals, received by a sensor; determining whether each of the plurality of received signals satisfies a condition (such as that a received signal is above a threshold level for indicating that an object is located in the region, or below a threshold level for indicating that an object is not located in the region); determining whether noise of at least a threshold amount is present; and determining whether an object is located within the region depending on whether at least a number of received signals meet the condition, the number being different when noise of at least a threshold amount is determined to be present than not present. For example, the required number of received signals that meet the condition when noise is present can be higher than when noise is absent. A device for detecting object according to the method is also disclosed.

First claim

We claim:

1. An object detection method, comprising:
transmitting a plurality of signals from a transmitter into a region;
measuring a plurality of signals, each corresponding to a respective one of the plurality of the transmitted signals, received by a sensor;
determining whether each of the plurality of received signals satisfies a condition;
determining whether noise of at least a threshold amount is present; and
determining whether an object is located within the region depending on whether at least a number of received signals meet the condition, the number being different when noise of at least a threshold amount is determined to be present than not present,
wherein:
the transmitting step comprises sequentially transmitting a plurality of optical pulses, during a respective plurality of repetition time intervals, into the region;
the measuring step comprises measuring each of the plurality of received signals during a signal measurement time interval beginning at or after a starting time of the corresponding transmitted signal;
the noise determination step comprises measuring noise during a noise measurement time interval in at least one of the repetition time intervals.

2. The method of claim 1 , wherein the step of determining whether an object is located within the region comprises determining that the transmitted signals are reflected into the sensor by an object located within the region, or a retro target, when the received signals exceed a first threshold level during at least a number of signal measurement time intervals, the number being a first number when noise is determined to be not present and the number being a second number greater than the first when noise is determined to be present.

3. The method of claim 2 , wherein determining that the transmitted signals are reflected into the sensor comprises determining that the transmitted signals are reflected into the sensor when the received signals exceed the first threshold level during at least a number of consecutive signal measurement time intervals.

4. The method of claim 1 , wherein the step of determining whether an object is located within the region comprises determining that the transmitted signals are not reflected into the sensor by any object located within the region, or any retro target, when the received signals falls below a second threshold level during at least a number of signal measurement time intervals, the number being a first number when noise is determined to be not present and the number being a second number smaller than the first when noise is determined to be present.

5. The method of claim 4 , wherein the noise determination step comprises determining that noise of at least a threshold amount is present when a signal above a noise threshold level is detected in at least a selected number of noise measurement time intervals.

6. The method of claim 5 , further comprising determining that a signal above the noise threshold level is detected in a noise measurement time interval when a signal measured in the noise measurement time interval has a level that crosses the noise threshold level at least a selected number of times.

7. The method of claim 5 , wherein the step of determining whether an object is located within the region comprises determining that the transmitted signals are not reflected into the sensor when the received signals fall below a second threshold level during at least a number of signal measurement time intervals, the number being a first number when noise is determined to be not present and the number being a second number smaller than the first when noise is determined to be present.

8. The method of claim 1 , wherein the noise determination step comprises measuring noise during a noise measurement time interval in each of a plurality of the repetition time intervals.

9. The method of claim 8 , wherein the noise determination step comprises determining that noise of at least a threshold amount is present when a signal above a noise threshold level is detected in at least a selected number of noise measurement time intervals.

10. The method of claim 9 , further comprising determining that a signal above the noise threshold level is detected in a noise measurement time interval when a signal measured in the noise measurement time interval has a level that crosses the noise threshold level at least a selected number of times.

11. An object detection method, comprising:
transmitting a plurality of signals, each during a respective one of a plurality of sequential repetition time intervals, from a transmitter into a region;
positioning a sensor to receive signals resulting from interactions between the transmitted signals and an object located in the region or a retro target;
measuring a plurality of signals received by the sensor during a respective plurality of signal measurement time intervals, each within a respective repetition time interval;
determining whether each of the plurality of received signals satisfies a condition;
measuring noise during a respective plurality of noise measurement time intervals, each within a respective repetition time interval and being different from any signal measurement time interval;
determining whether the measured noise is present in at least a threshold amount; and
determining whether an object is located within the region depending on whether the received signals satisfy the condition during at least a number of repetition time intervals, the number being different when noise of at least a threshold amount is determined to be present than not present.

12. The method of claim 11 , wherein the step of measuring noise comprises measuring signals received by the sensor during the plurality of noise measurement time intervals.

13. The method of claim 11 , wherein:
the step of determining whether each of the plurality of received signals satisfies a condition comprises determining, after determining that the transmitted signals are not reflected into the sensor, whether each of the plurality of received signals is above a first threshold level during the signal measurement time interval; and
the step of determining whether an object is located within the region comprises determining that the transmitted signals are reflected into the sensor when the received signals during the respective signal measurement time intervals are above the first threshold level during at least a number of repetition time intervals, the number being higher when noise of at least a threshold amount is determined to be present than not present.

14. The method of claim 11 , wherein:
the step of determining whether each of the plurality of received signals satisfies a condition comprises determining, after determining that the transmitted signals are reflected into the sensor, whether each of the plurality of received signals is below a second threshold level during the signal measurement time interval; and
the step of determining whether an object is located within the region comprises determining that the transmitted signals are not reflected into the sensor when the received signals during the respective signal measurement time intervals are below the second threshold level during at least a number of repetition time intervals, the number being smaller when noise of at least a threshold amount is determined to be present than not present.

15. The method of claim 14 , further comprising determining that a signal above the noise threshold level is detected in a noise measurement time interval when a signal measured in the noise measurement time interval has a level that crosses t

Assignees

• Banner Eng
• Banner Eng

Inventors

• Stecker John Alyn
• Carlsten Keith Donald
• Anderson David Steven

Classifications

• G01V8/10 Primary

  Detecting, e.g. by using light barriers (by reflection from the object G01S17/00) · CPC title