Device for determining a distance to an object and corresponding method

Patent metadata

Field	Value
Publication number	US-11067674-B2
Application number	US-201815896162-A
Country	US
Kind code	B2
Filing date	Feb 14, 2018
Priority date	Feb 14, 2017
Publication date	Jul 20, 2021
Grant date	Jul 20, 2021

Abstract

Described are a device for determining a distance to an object, having a transmitting device for emitting signals, a receiving device for receiving signals and for generating detection signals, an evaluating device for evaluating the detection signals of the receiving device, and a control device for controlling the evaluation of the detection signals, and a corresponding method. The receiving device has a plurality of receiving elements which generate, in case they receive a signal, a detection signal each. The evaluating device determines the distance to the object in accordance with the time-of-flight method and while considering coincidence events and uses that case in which a number of detection signals generated within a presettable coincidence time at least equals a presettable coincidence depth, as a coincidence events. The control device is configured to determine, starting from a background radiation measurement, a new value for the coincidence time and/or, if applicable, the coincidence depth and preset same for the evaluating device, wherein, in a background radiation measurement, the receiving device receives signals and generates background radiation detection signals.

First claim

The invention claimed is:

1. A device for determining a distance to an object,
comprising a transmitting device for emitting signals,
comprising a receiving device for receiving signals and for generating detection signals,
comprising an evaluating device for evaluating the detection signals of the receiving device, and
comprising a control device for controlling the evaluation of the detection signals of the receiving device by the evaluating device,
wherein the receiving device comprises a plurality of receiving elements,
wherein the receiving elements are configured to, in case they receive a signal, generate a detection signal each,
wherein the evaluating device is configured to determine the distance to the object in accordance with the time-of-flight method and while,
a number of detection signals generated within a presettable coincidence time at least equals a presettable coincidence depth,
wherein the control device is configured to determine, starting from a background radiation measurement, a new value for the coincidence time and preset same for the evaluating device,
wherein, in a background radiation measurement, the receiving device receives signals and generates background radiation detection signals,
wherein, in a background radiation measurement, the evaluating device evaluates the background radiation detection signals using a current coincidence time and a current coincidence depth,
wherein the control device is configured to compare a number of background radiation detection signals acquired in the background radiation measurement to an event set value, and
wherein the control device is configured to, in case the number of background radiation detection signals and the event set value differ beyond a presettable threshold value, determine at least the coincidence time and/or the coincidence depth starting from the number of background radiation detection signals.

2. The device in accordance with claim 1 ,
wherein the control device is configured to determine, starting from a background radiation measurement, a new value for the coincidence time and/or a new value for the coincidence depth and preset same for the evaluating device.

3. The device in accordance with claim 1 ,
wherein the control device is configured to, in case the number of background radiation detection signals is greater than the event set value, decrease the current coincidence time for determining the new value of the coincidence time, and
wherein the control device is configured to, in case the number of background radiation detection signals is smaller than the event set value, increase the current coincidence time for determining the new value of the coincidence time.

4. The device in accordance with claim 3 ,
wherein the control device is configured to, in case the current coincidence time reaches a presettable maximum threshold value, decrease the current coincidence depth for determining the new value of the coincidence depth and to set the new value of the coincidence time to a presettable minimum value, and
wherein the control device is configured to, in case the current coincidence time reaches a presettable minimum threshold value, increase the current coincidence depth for determining the new value of the coincidence depth and to set the new value of the coincidence time to a presettable maximum value.

5. The device in accordance with claim 1 ,
wherein the control device is configured to determine the new value for the coincidence time and/or the new value for the coincidence depth using the number of background radiation detection signals which results when a number of detection signals generated within a presettable coincidence time at least equals a presettable coincidence depth.

6. The device in accordance with claim 1 ,
wherein the control device is configured to use, at least for determining the new value of the coincidence time, the number of all the background radiation detection signals which result in a background radiation measurement when a number of detection signals generated within a presettable coincidence time does not equal a presettable coincidence depth.

7. The device in accordance with claim 1 ,
wherein the control device is configured to determine the new value of the coincidence time and/or the new value of the coincidence depth using data stored in a data storage, in dependence on the number of background radiation detection signals.

8. The device in accordance with claim 1 ,
wherein the control device is configured to cause a background radiation measurement before each distance measurement.

9. The device in accordance with claim 1 ,
wherein the receiving elements of the receiving device are associated to several image elements, and
wherein the receiving device is configured such that, when receiving signals, a number of receiving elements per pixel activated for receiving the signals equals the set coincidence depth.

10. The device in accordance with claim 1 ,
wherein pulse shapers of variable pulse widths are associated to the receiving elements, and
wherein the pulse shapers each generate a pulse with the coincidence time as a pulse width in case the associated receiving elements receive signals.

11. The device in accordance with claim 1 ,
wherein the receiving elements are avalanche photodiodes.

12. The device in accordance with claim 1 ,
wherein the transmitting device comprises an infrared light laser.

13. A method for determining a distance to an object,
wherein signals are emitted,
wherein signals are received and, starting therefrom, detection signals are generated,
wherein the distance to the object is determined from the detection signals in accordance with the time-of-flight method and while,
a number of detection signals generated within a presettable coincidence time at least equals a presettable coincidence depth,
wherein, starting from a background radiation measurement, the coincidence time and/or the coincidence depth are/is determined,
wherein, in a background radiation measurement, the background radiation detection signals are evaluated using a current coincidence time and a current coincidence depth,
wherein a number of background radiation detection signals acquired in the background radiation measurement is compared to an event set value, and
wherein, in case the number of background radiation detection signals and the event set value differ beyond a presettable threshold value, at least the coincidence time and/or the coincidence depth is determined starting from the number of background radiation detection signals.

Assignees

• Fraunhofer Ges Forschung

Inventors

• Schrey Olaf
• Beer Maik
• Brockherde Werner
• Hosticka Bedrich
• Schwinger Alexander
• Arutinov David

Classifications

• G01S7/4876

  by removing unwanted signals (G01S7/495 takes precedence) · CPC title

• G01S7/4863

  Detector arrays, e.g. charge-transfer gates · CPC title

• G01S17/10

  using transmission of interrupted, pulse-modulated waves (determination of distance by phase measurements G01S17/32) · CPC title

• G01S17/89

  for mapping or imaging · CPC title

• G01S7/487 Primary

  Extracting wanted echo signals {, e.g. pulse detection} · CPC title