ADAPTIVE DISTANCE ESTIMATION

• US 20150077542A1
• Filed: 09/18/2013
• Published: 03/19/2015
• Est. Priority Date: 09/18/2013
• Status: Active Grant

• Current Assignee: Infineon Technologies AG
• Original Assignee: Infineon Technologies AG
• Inventors: STEINER, Christoph, MARK, Michael, GRUENWALD, Johannes
• Granted Patent: US 10,132,626 B2
• Time in Patent Office: Days
• US Class Current: 348/135
• 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 arranged to capture light radiation reflected off one or more objects in an area during a frame event; and

a processing component arranged to calculate a 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 event, the phase delay values corresponding to one set of a plurality of sets of reference phases.

2. The apparatus of claim 1, wherein the processing component is arranged to select a set of reference phases from the plurality of sets of reference phases for each frame event according to an algorithm.

3. The apparatus of claim 1, wherein the processing component is arranged to calculate a distance from the one or more objects to the imaging sensor using a different set of reference phases of the plurality of sets of reference phases during a subsequent frame event.

4. The apparatus of claim 1, wherein the processing component is arranged to calculate the distance from the one or more objects to the imaging sensor based on one or more phase delay values of light radiation captured during a past frame event.

5. The apparatus of claim 1, wherein the processing component is arranged to calculate the distance from the one or more objects to the imaging sensor based on one or more phase delay values of light radiation captured during a present frame event combined with one or more phase delay values of light radiation captured during one or more past frame events.

6. The apparatus of claim 5, wherein the processing component is arranged to adaptively select a quantity of the one or more past frame events based on whether object movement is detected within the area within a preset time duration.

7. The apparatus of claim 6, wherein the quantity of the one or more past frame events is adaptively selected based on a speed of the object movement detected within the area within the preset time duration, wherein fewer past frame events are selected when faster object movement is detected within the area within the preset time duration, and more past frame events are selected when slower object movement is detected within the area within the preset time duration, the object movement detection dependent on phase information obtained from at least one pixel.

8. The apparatus of claim 6 wherein the processing component is arranged to detect object movement within the area based on an analysis of the temporal evolution of the one or more phase delay values of light radiation captured during a present frame event and during one or more past frame events.

9. The apparatus of claim 1, wherein the imaging sensor is comprised of multiple pixel devices, and wherein the processing component is arranged to calculate a distance from the one or more objects to each pixel device of the imaging sensor based on one or more phase delay values of light radiation captured by the pixel device.

10. The apparatus of claim 1, wherein a first set of reference phases of the plurality of sets of reference phases comprises 0 degrees, 120 degrees, and 240 degrees, and a second set of reference phases of the plurality of sets of reference phases comprises 180 degrees, 300 degrees, and 60 degrees.

11. The apparatus of claim 1, wherein the imaging sensor is arranged to capture a three-dimensional image of the area using time-of-flight principles during a frame event.

12. A system, comprising:

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

a sensor module comprising a plurality of pixels arranged to capture one or more phase delay values of the light radiation reflected off one or more objects in the area during a frame event, the phase delay values corresponding to one set of a plurality of alternating sets of reference phases; and

a control module arranged to calculate a distance from the one or more objects to individual pixels of the plurality of pixels, based on the one or more phase delay values captured by the individual pixels.

13. The system of claim 12, the control module further arranged to select the set of reference phases from the plurality of alternating sets of reference phases for the frame event according to an algorithm, and to select another set of reference phases from the plurality of alternating sets of reference phases for a subsequent frame event, according to the algorithm.

14. The system of claim 12, the control module further arranged to calculate the distance from the one or more objects to a pixel based on one or more phase delay values of light radiation captured by the pixel during a present frame event combined with one or more phase delay values of light radiation captured by the pixel during one or more past frame events, the control module arranged to adaptively select a quantity of the one or more past frame events during runtime, based on a speed of object movement indicated with respect to the pixel and/or based on minimizing the occurrence of motion artifacts.

15. The system of claim 12, wherein each set of reference phases comprises three or more equally-spaced phase angles and the phase delay values comprise a corresponding quantity of phase shifts relative to each reference phase angle.

16. A method, comprising:

capturing light radiation reflected off one or more objects within an area during a frame event, with an imaging sensor;

selecting a set of reference phase values from a plurality of sets of reference phase values;

determining one or more phase delay values of the light radiation captured during the frame event, corresponding to the set of reference phase values selected; and

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

17. The method of claim 16, further comprising selecting a subsequent set of reference phase values from the plurality of sets of reference phase values for each subsequent frame event according to an algorithm, determining one or more phase delay values of light radiation captured during the subsequent frame event corresponding to the set of reference phase values selected, and calculating a distance from the one or more objects to the imaging sensor based on the one or more corresponding phase delay values of the light radiation captured during the subsequent frame event.

18. The method of claim 16, further comprising calculating the distance from the one or more objects to the imaging sensor based on one or more phase delay values of light radiation captured during a present frame event combined with one or more phase delay values of light radiation captured during one or more past frame events.

19. The method of claim 18, further comprising calculating a distance from the one or more objects to a pixel of the imaging sensor and adaptively selecting a quantity of frame events for the distance calculation relative to the pixel based on detecting a threshold object movement within a portion of the area corresponding to the pixel during runtime, and reusing a distance calculation from the one or more objects to the pixel when no threshold object movement is detected relative to the pixel.

20. The method of claim 19, further comprising adaptively selecting the quantity of frame events for the distance calculation based on a speed of object movement detected, including increasing a quantity of frame events selected when the speed of object movement decreases and decreasing a quantity of frame events selected when the speed of object movement increases.

21. The method of claim 19, wherein the frame events selected for the distance calculation relative to the pixel are temporally non-sequential.

22. The method of claim 18, further comprising mitigating an occurrence of motion artifacts and/or averaging imaging noise by adaptively selecting a quantity of past frame events for the distance calculation, based on a speed of object movement detected within the area.

23. The method of claim 16, further comprising analyzing a temporal sequence of phase shifts of the phase delay values over a series of frame events to detect object movement within the area, a threshold change in a phase delay value relative to a pixel of the imaging sensor indicating a change in a distance of an object within a portion of the area corresponding to the pixel.

24. The method of claim 16, further comprising defining a phase shift of a phase delay value at a present frame event as a former phase shift of a previous frame event plus an update term, to calculate the distance from the one or more objects to the imaging sensor, the update term indicating a change in distance of the one or more objects from a time of the previous frame event to a time of the present frame event.

25. A three-dimensional imaging device, comprising:

an imaging sensor arranged 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 one or more phase delay values of light radiation reflected off one or more objects in an area during multiple frame events, the phase delay values corresponding to a sequence of sets of reference phases, each set of the sequence of sets of reference phases arranged to be applied to a frame event of the multiple frame events according to an algorithm; and

a processing component arranged to calculate a distance from the one or more objects to individual pixels of the imaging sensor, based on the one or more phase delay values of the light radiation captured during one or more frame events of the multiple frame events, the processing component arranged to process a quantity of the multiple frame events to calculate the distance based on a speed of object movement detected within the area.