Time of flight system and method using multiple measuring sequences

Patent metadata

Field	Value
Publication number	US-10996324-B2
Application number	US-201815978728-A
Country	US
Kind code	B2
Filing date	May 14, 2018
Priority date	May 14, 2018
Publication date	May 4, 2021
Grant date	May 4, 2021

Abstract

A time of flight sensor device is capable of extending its total sensing distance using multiple measuring sequences for each distance measuring operation. Such embodiments can execute two or more iterations of a measuring sequence, where the gating signal control sequence for each measuring sequence is offset in time relative to a previous sequence. This yields a greater number of sampling points within which a reflected pulse can be detected and measured, resulting in a total measurable time of flight range that is greater than a measuring operation that uses a fixed timing for the gating signals.

First claim

What is claimed is:

1. A time of flight sensor device, comprising:
an emitter component configured to emit a light pulse at a first time during each measuring sequence of at least two measuring sequences of a distance measurement operation;
a photo-sensor component comprising a photo-detector, the photo-detector comprising
a photo device configured to generate electrical energy in proportion to a quantity of received light,
a first measuring capacitor connected to the photo device via a first control line switch controlled by a first gating signal,
a second measuring capacitor connected to the photo device via a second control line switch controlled by a second gating signal, and
a third measuring capacitor connected to the photo device via a third control line switch controlled by a third gating signal,

wherein the photo-sensor component is configured to, for each measuring sequence of the at least two measuring sequences,
set the first gating signal, at a second time during the measuring sequence defined relative to the first time, and reset the first gating signal at a third time during the measuring sequence defined relative to the first time, wherein setting the first gating signal at the second time and resetting the first gating signal at the third time causes a first portion of the electrical energy to be stored in the first measuring capacitor,
set the second gating signal at the third time and reset the second gating signal at a fourth time during the measuring sequence defined relative to the first time, wherein setting the second gating signal at the third time and resetting the second gating signal at the fourth time causes a second portion of the electrical energy to be stored in the second measuring capacitor, and
set the third gating signal at the fourth time and reset the third gating signal at a fifth time during the measuring sequence defined relative to the first time, wherein setting the third gating signal at the fourth time and resetting the third gating signal at the fifth time causes a third portion of the electrical energy to be stored in the third measuring capacitor,
wherein the second time, the third time, the fourth time, and the fifth time are offset within a second measuring sequence of the at least two measuring sequences relative to a first measuring sequence of the at least two measuring sequences; and

a distance determination component configured to determine a propagation time for the light pulse based on first measured values of the first portion of the electrical energy measured on the first measuring capacitor for the at least two measuring sequences, second measured values of the second portion of the electrical energy measured on the second measuring capacitor for the at least two measuring sequences, and third measured values of the third portion of the electrical energy measured on the third measuring capacitor for the at least two measuring sequences.

2. The time of flight sensor device of claim 1 , wherein the distance determination component is configured to
identify a subset of the at least two measuring sequences for which the third time or the fourth time coincides with a duration during which a reflected light pulse corresponding to the light pulse is received by the photo-detector, and
calculate one or more propagation time values respectively corresponding to the subset of the at least two measuring sequences based on a subset of the first measured values, a subset of the second measured values, and a subset of the third measured values corresponding to the subset of the at least two measuring sequences.

3. The time of flight sensor device of claim 2 , wherein the distance determination component is configured to, for each measuring sequence of the subset of the at least two measuring sequences:
in response to a determination that a first measured value, of the subset of the first measured values, corresponding to the measuring sequence represents a leading edge portion of the reflected light pulse:
subtract a third measured value, of the subset of the third measured values, corresponding to the measuring sequence from the first measured value to yield a leading edge value, and
subtract the third measured values from a second measured value, of the subset of the second measured values, corresponding to the measuring sequence to yield a trailing edge value; and

in response to a determination that the second measured value corresponding to the measuring sequence represents the leading edge portion of the reflected light pulse:
subtract the first measured value from the second measured value to yield the leading edge value, and
subtract the first measured value from the third measured value to yield the trailing edge value; and

determine a propagation time value of the one or more propagation time values based on a ratio of the trailing edge value to a total of the leading edge value and the trailing edge value.

4. The time of flight sensor of claim 3 , wherein the distance determination component is configured to
determine that the first measured value represents the leading edge portion of the reflected light pulse based on a determination that the first measured value and the second measured value are greater than the third measured value, and
determine that the second measured value represents the leading edge portion of the reflected light pulse based on a determination that the second measured value and the third measured value are greater than the first measured value.

5. The time of flight sensor device of claim 2 , wherein the distance determination component is configured to:
in response to determining that the one or more propagation time values comprise only one propagation time value, set the propagation time to be the one propagation time value.

6. The time of flight sensor device of claim 2 , wherein the distance determination component is configured to:
in response to determining that the one or more propagation time values comprise multiple propagation time values, set the propagation time as a function of the multiple propagation time values.

7. The time of flight sensor device of claim 6 , wherein the distance determination component is configured to determine the propagation time based on an average of the multiple propagation time values.

8. The time of flight sensor device of claim 6 , wherein the distance determination component is configured to select one of the multiple propagation time values as the propagation time based on a selection criterion.

9. The time of flight sensor device of claim 2 , wherein the distance determination component is configured to calculate the one or more propagation time values based on

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Assignees

• Rockwell Automation Tech Inc

Inventors

• Boutaud Frederic

Classifications

• G01S17/89 Primary

  for mapping or imaging · CPC title

• G01S7/4865 Primary

  Time delay measurement, e.g. time-of-flight measurement, time of arrival measurement or determining the exact position of a peak (peak detection in noise, signal conditioning G01S7/487) · CPC title

• G01S17/18

  wherein range gates are used · CPC title