Adaptive distance estimation

• US 10,132,626 B2
• Filed: 09/18/2013
• Issued: 11/20/2018
• Est. Priority Date: 09/18/2013
• Status: Active Grant

• Current Assignee: Infineon Technologies AG
• Original Assignee: Infineon Technologies AG
• Inventors: Steiner, Christoph, Gruenwald, Johannes, Mark, Michael
• Primary Examiner(s): Matt, Marnie A
• Application Number:
  US14/030,893
• Publication Number:
  US 20150077542A1
• Time in Patent Office: 1,889 Days
• CPC Class Codes: G01C 3/00 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 Class Codes: G01S 17/36 with phase comparison between the received signal and the contemporaneously transmitted signal
• CPC Class Codes: G01S 17/66 Tracking systems using electromagnetic waves other than radio waves
• CPC Class Codes: G01S 17/931 of land vehicles
• CPC Class Codes: G01S 7/4914 of detector arrays, e.g. charge-transfer gates
• CPC Class Codes: G01S 7/4915 Time delay measurement, e.g. operational details for pixel components signal extraction and conditioning G01S7/493; Phase measurement
• CPC Class Codes: H04N 23/56 provided with illuminating means
• CPC Class Codes: H04N 5/144 Movement detection for video coding H04N19/503; analysis of motion in general G06T7/20

Abstract

Representative implementations of devices and techniques provide adaptive distance estimation for imaging devices and systems. Distance estimation may be based on phase delays in reflected light. Reference phases used to determine phase delay values may be changed for subsequent frame events. Multiple frame events may be selected for some distance calculations based on whether object movement is detected within a predetermined area.

Claims

1. An apparatus, comprising:

an imaging sensor to capture light radiation reflected off of one or more objects in an area during a frame and a subsequent frame; and

a processing component configured to;

select a first set of reference phases used to index phase shifts in the light radiation captured during the frame;

select a second set of reference phases used to index phase shifts in the light radiation captured during the subsequent frame,

the first set of reference phases being different than the second set of reference phases;

calculate a first distance from the one or more objects to the imaging sensor based on one or more phase delay values of the light radiation captured during the frame,

the one or more phase delay values corresponding to the first set of reference phases, and

calculate a second distance from the one or more objects to the imaging sensor using the second set of reference phases during the subsequent frame.

2. The apparatus of claim 1, where the processing component, when selecting the first set of reference phases, is configured to:

select the first set of reference phases according to an algorithm.

3. The apparatus of claim 1, where the processing component, when calculating the first distance, is configured to:

calculate the first distance based on one or more phase delay values associated with a past frame.

4. The apparatus of claim 1, where the processing component, when calculating the first distance, is configured to:

calculate the first distance based on the one or more phase delay values and sets of phase delay values associated with a plurality of past frames.

5. The apparatus of claim 4, where the processing component is configured to:

adaptively select a quantity of the plurality of past frames based on whether object movement is detected within the area within a preset time duration.

6. The apparatus of claim 5, where the quantity of the plurality of past frames is adaptively selected based on a speed of the object movement,

a first quantity of the plurality of past frames being selected when the speed of the object movement satisfies a threshold, or

a second quantity of the plurality of past frames being selected when the speed of the object movement does not satisfy the threshold,

the first quantity being different from the second quantity.

7. The apparatus of claim 5, where the processing component is configured to:

detect the object movement based on an analysis of a temporal evolution of the one or more phase delay values in relation to the sets of phase delay values associated with the plurality of past frames.

8. The apparatus of claim 1, where the imaging sensor is comprised of multiple pixel devices, and

where the processing component is configured to calculate multiple distances from the one or more objects,

each distance, of the multiple distances, corresponding to a pixel device of the multiple pixel devices.

9. The apparatus of claim 1, where the first set of reference phases comprises 0 degrees, 120 degrees, and 240 degrees, and the second set of reference phases comprises 180 degrees, 300 degrees, and 60 degrees.

10. The apparatus of claim 1, where the imaging sensor is configured to capture a three-dimensional image of the area using time-of-flight principles during the frame.

11. A system, comprising:

an illumination module to emit light radiation to illuminate an area;

a sensor module, comprising a plurality of pixels, to capture one or more phase delay values of the light radiation after reflection off of one or more objects in the area during a frame and a subsequent frame,

the one or more phase delay values corresponding to alternating sets of reference phases; and

a control module configured to;

select a first set of reference phases, of the alternating sets of reference phases, used to index phase shifts in the light radiation captured during the frame;

select a second set of reference phases, of the alternating sets of reference phases, used to index phase shifts in the light radiation captured during the subsequent frame,

the first set of reference phases being different than the second set of reference phases;

calculate a first distance between the one or more objects and a pixel, of the plurality of pixels, based on a first set of phase delay values, corresponding to the first set of reference phases associated with the frame; and

calculate a second distance between the one or more objects and the pixel using the second set of reference phases during the subsequent frame.

12. The system of claim 11, where the control module is further configured to:

select the second set of reference phases according to an algorithm.

13. The system of claim 11, where the control module, when calculating the first distance, is configured to:

calculate the first distance based on the first set of phase delay values and one or more phase delay values associated with one or more past frames,

where the control module is to adaptively select a quantity of the one or more past frames based on a speed of object movement indicated with respect to the pixel or based on minimizing an occurrence of motion artifacts.

14. The system of claim 11, where each set of reference phases, of the alternating sets of reference phases, comprises three or more equally-spaced phase angles, and each set of reference phases comprises a corresponding quantity of phase delay values.

15. A method, comprising:

capturing, by an imaging sensor, light radiation reflected off of one or more objects within an area during a frame and a subsequent frame;

selecting, by a processing component, a first set of reference phases used to index phase shifts in the light radiation captured during the frame;

selecting, by the processing component, a second set of reference phases used to index phase shifts in the light radiation captured during the subsequent frame,

the first set of reference phases being different than the second set of reference phases;

calculating, by the processing component, a first distance, from the one or more objects to the imaging sensor, based on one or more phase delay values of the light radiation captured during the frame, and

the one or more phase delay values corresponding to the first set of reference phases, and

calculating, by the processing component, a second distance from the one or more objects to the imaging sensor using the second set of reference phases during the subsequent frame.

16. The method of claim 15,

where the method further comprises:

selecting the second set of reference phases, according to an algorithm.

17. The method of claim 15, where calculating the first distance comprises:

calculating the first distance further based on one or more phase delay values associated with one or more past frames.

18. The method of claim 15, where the first distance corresponds to a pixel of the imaging sensor, and

where the method further comprises:

adaptively selecting a quantity of frames for calculating the first distance when a threshold object movement, within a portion of the area corresponding to the pixel, is detected;

or

reusing the first distance when no threshold object movement is detected within the portion of the area corresponding to the pixel.

19. The method of claim 18, where adaptively selecting a quantity of frames comprises:

adaptively selecting the quantity of frames based on a speed of the threshold object movement detected, including increasing the quantity of frames selected when the speed of the threshold object movement decreases or decreasing the quantity of frames selected when the speed of the threshold object movement increases.

20. The method of claim 18, where frames corresponding to the quantity of frames are temporally non-sequential.

21. The method of claim 15, further comprising:

mitigating an occurrence of motion artifacts or averaging imaging noise by adaptively selecting a quantity of past frames for calculating the first distance,

the quantity of past frames being selected based on a speed of object movement detected within the area.

22. The method of claim 15, further comprising:

analyzing a temporal sequence of phase shifts of the phase delay values over a series of frames, including the frame, to detect object movement within the area,

where a threshold change in a phase delay value, of the one or more phase delay values, indicates a change in a distance.

23. The method of claim 15, further comprising:

defining a phase shift of a phase delay value at the frame as a former phase shift of a previous frame plus an update term in order to calculate the first distance from the one or more objects to the imaging sensor,

where the update term indicates a change in the first distance from a time of the previous frame to a time of the frame.

24. A three-dimensional imaging device, comprising:

an imaging sensor to capture a three-dimensional image of an area based on time-of-flight principles,

the imaging sensor comprising;

a plurality of pixels arranged to capture light radiation reflected off of an object in the area during a frame and a subsequent frame; and

a processing component configured to;

select a first set of reference phases used to index phase shifts in the light radiation captured during the frame;

select a second set of reference phases used to index phase shifts in the light radiation captured during the subsequent frame,

the first set of reference phases being different than the second set of reference phases;

calculate a first distance from the object to the imaging sensor based on one or more phase delay values of the light radiation captured during the frame,

the one or more phase delay values corresponding to the first set of reference phases; and

calculate a second distance from the object to the imaging sensor using the second set of reference phases during the subsequent frame.