Acquisition of distance data with optical ranging systems

Patent metadata

Field	Value
Publication number	US-11067691-B2
Application number	US-201615775490-A
Country	US
Kind code	B2
Filing date	Nov 14, 2016
Priority date	Nov 13, 2015
Publication date	Jul 20, 2021
Grant date	Jul 20, 2021

Abstract

This disclosure is directed to methods for acquiring distance data using optical ranging systems. Optical ranging systems include one or more reference pixels and one or more object pixels. The methods employ operations for optimizing reference-pixel integration times and object-pixel integration times such that accurate distance data can be collected.

First claim

What is claimed is:

1. A method for collecting distance data with an optical ranging system, the method comprising:
initializing the optical ranging system, the optical ranging system including at least one reference pixel operable to convert incident light to electrical charges, and at least one object pixel operable to convert incident light to electrical charges;
directing incident light to the at least one reference pixel and the at least one object pixel, collecting electrical charges with the at least one reference pixel over an initial reference-pixel integration time, and collecting electrical charges with the at least one object pixel over an initial object-pixel integration time;
correlating the electrical charges collected with the at least one reference pixel over the initial reference-pixel integration time to an initial reference signal having an initial reference signal intensity;
correlating the electrical charges collected with the at least one object pixel over the initial object-pixel integration time to an initial object signal having an initial object-signal intensity;
determining an optimal reference pixel integration time and an optimal object pixel integration time from the initial reference signal and the initial object signal;
collecting electrical charges with the at least one reference pixel over the optimal reference pixel integration time, and collecting electrical charges with the at least one object pixel over the optimal object pixel integration time;
correlating the electrical charges collected with the at least one reference pixel over the optimal reference pixel integration time to an optimal reference signal, and correlating the electrical charges collected with the at least one object pixel over the optimal object pixel integration time to an optimal object signal; and
determining distance data from the optimal reference signal and the optimal object signal,
wherein determining the optimal reference-pixel-integration time and the optimal object-pixel-integration time from the initial reference signal and the initial object signal further includes:
determining a calculated reference-pixel-integration time, and determining a calculated object-pixel-integration time;
comparing the calculated reference-pixel-integration time to a pre-established minimum integration time and a pre-established maximum integration time;
comparing the calculated object-pixel-integration time to the pre-established minimum integration time and the pre-established maximum integration time;
equating the optimal reference-pixel-integration time to the calculated reference-pixel-integration time or the calculated object-pixel-integration time; and
equating the optimal object-pixel-integration time to the calculated object-pixel-integration time; and

wherein determining the calculated-reference-pixel-integration time further includes:
comparing the initial reference-signal intensity to a pre-established reference-signal intensity threshold;
increasing the initial reference-pixel integration time for initial reference-signal intensities lower than the pre-established reference-signal intensity threshold;
decreasing the initial reference-pixel integration time for initial reference-signal intensities greater than the pre-established reference-signal intensity threshold; and
equating the initial reference-pixel integration time to the calculated-reference-pixel-integration time.

2. The method according to claim 1 , further including equating the optimal reference pixel integration time to the calculated reference pixel integration time for calculated reference pixel integration times less than the pre-established minimum integration time and greater than the pre-established maximum integration time.

3. The method according to claim 1 , further including equating the optimal reference pixel integration time to the calculated object pixel integration time for calculated reference pixel integration times equal to or between the pre-established minimum integration time and the pre-established maximum integration time.

4. The method according to claim 1 , wherein determining the calculated-object-pixel-integration time further includes:
comparing the initial object signal intensity to a pre-established object-signal intensity threshold;
increasing the initial object-pixel integration time for initial object signal intensities lower than the pre-established object-signal intensity threshold;
decreasing the initial object-pixel integration time for initial object signal intensities greater than the pre-established object-signal intensity threshold; and
equating the initial object-pixel integration time to the calculated-object-pixel-integration time.

5. The method according to claim 1 , further including:
equating the initial reference-signal intensity to an initial reference-signal signal-to-noise ratio;
equating the initial object-signal intensity to an initial object-signal signal-to-noise ratio; and
equating the pre-established reference-signal intensity threshold to a pre-stablished reference-signal signal-to-noise threshold.

6. The method according to claim 4 , further including:
equating the initial reference-signal intensity to an initial reference-signal signal-to-noise ratio;
equating the initial object-signal intensity to an initial object-signal signal-to-noise ratio; and
equating the pre-established object-signal intensity threshold to a pre-established object-signal signal-to-noise threshold.

7. The method according to claim 1 , wherein collecting electrical charges with the at least one reference pixel over an initial reference-pixel integration time, and collecting electrical charges with the at least one object pixel over an initial object-pixel integration time are initiated simultaneously.

8. The method according to claim 7 , wherein collecting electrical charges with the at least one reference pixel over the optimal reference pixel integration time, and collecting electrical charges with the at least one object pixel over the optimal object pixel integration time are initiated simultaneously.

9. The method according to claim 1 , wherein directing incident light to the at least one reference pixel and the at least one object pixel includes modulating the incident light with a particular modulation frequency.

10. The method according to claim 9 , wherein at least one reference pixel is a demodulation pixel and at least one object pixel is a demodulation pixel.

11. The method according to claim 10 , wherein determining distance data from the optimal reference signal and the optimal object signal includes determining distance data by the indirect time-of-flight technique.

12. The method according to claim 11 , further including equating the optimal reference pixel integration time to the calculated reference pixel integration time for calculated reference pixel integration times less than the pre-established minimum integration time and greater than the pre-established maximum integration time.

13. The method according to claim 11 , further including equating the optimal reference pixel integration time to the calculated object pixel integration time for calculated reference pixel integration times equal to or between the pre-established minimum integration time and the pre-established maximum integration time.

14. The method according to claim 11 , wherein:
collecting electrical charges with the at least one reference pixel over an initial reference-pixel integration time, and collecting electrical charges with the at least one object pixel over an initial object-pixel integration time are

Assignees

• Ams Sensors Singapore Pte Ltd

Inventors

• Vaello Paños Miguel Bruno
• Strässle Cassian
• Hansen Bryant

Classifications

• G01C3/00 Primary

  Measuring distances in line of sight; Optical rangefinders (tapes, chains or wheels for measuring length G01B3/00; active triangulation systems, i.e. using the transmission and reflection of electromagnetic waves other than radio waves, G01S17/48) · CPC title

• G01S17/08

  for measuring distance only (indirect measurement G01S17/46; active triangulation systems G01S17/48) · CPC title

• G01S7/493

  Extracting wanted echo signals · CPC title

• G01S7/4914

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

• G01S17/32 Primary

  using transmission of continuous waves, whether amplitude-, frequency-, or phase-modulated, or unmodulated · CPC title