Determining positional information of an object in space

Patent metadata

Field	Value
Publication number	US-9702977-B2
Application number	US-201414214605-A
Country	US
Kind code	B2
Filing date	Mar 14, 2014
Priority date	Mar 15, 2013
Publication date	Jul 11, 2017
Grant date	Jul 11, 2017

Abstract

The technology disclosed relates to determining positional information of an object in a field of view. In particular, it relates to calculating a distance of the object from a reference such as a sensor including scanning the field of view by selectively illuminating directionally oriented light sources and measuring one or more differences in property of returning light emitted from the light sources and reflected from the object. The property can be intensity or phase difference of the light. It also relates to finding an object in a region of space. In particular, it relates to scanning the region of space with directionally controllable illumination, determining a difference in a property of the illumination received for two or more points in the scanning, and determining positional information of the object based in part upon the points in the scanning corresponding to the difference in the property.

First claim

What is claimed is:

1. A method of tracking motion of a target object for gesture control of a system by determining positional information of the target object moving in a region of space within range of a light sensitive sensor, the method including:
scanning the region of space monitored by the light sensitive sensor by selectively illuminating respective directionally oriented non-coplanar light sources of a plurality of directionally oriented non-coplanar light sources that (i) are mounted to a single non-coplanar surface and (ii) have at least some overlapping fields of illumination;
measuring, using the light sensitive sensor, one or more differences in an intensity of returning light emitted from the respective directionally oriented non-coplanar light sources and reflected from the target object as the target object moves through the region of space;
determining positional information of the target object based on, at least, a first position in space at a first time t 0 and a second position in space at a second time t 1 sensed using the measured one or more differences in the intensity of the returning light;
determining a movement of the target object in response to a difference in the determined positional information of the target object at the first time t 0 and the second time t 1 ; and
recognizing gesture control in response to the determined movement of the target object.

2. The method of claim 1 , wherein the selectively illuminating of the respective directionally oriented non-coplanar light sources includes varying a brightness of a pair of overlapping directionally oriented non-coplanar light sources by dimming a first directionally oriented non-coplanar light source of the pair, which is initially on while brightening a second directionally oriented non-coplanar light source of the pair, which is initially off.

3. The method of claim 2 , further including varying the brightness of the pair of overlapping directionally oriented non-coplanar light sources according to a quadratic formula.

4. The method of claim 2 , further including varying the brightness of the pair of overlapping directionally oriented non-coplanar light sources according to a Gaussian distribution.

5. The method of claim 2 , further including illuminating two or more directionally oriented non-coplanar light sources of the plurality of directionally oriented non-coplanar light sources respectively at different intensities of illumination.

6. The method of claim 2 , further including performing a coarse scan of the region of space to assemble a low-resolution estimate of a position of the target object by illuminating a subset of directionally oriented non-coplanar light sources from the plurality of directionally oriented non-coplanar light sources.

7. The method of claim 6 , further including:
following the coarse scan by performing a fine grained scan of a subsection the region of space view based on the low-resolution estimate of the position of the target object; and
identifying distinguishing features of the target object based on a high-resolution data set collected during the fine grained scan.

8. The method of claim 1 , further including selectively illuminating the respective directionally oriented non-coplanar light sources one at a time.

9. The method of claim 1 , further including the light sensitive sensor scanning the region of space using a scanning mirror and a photo detector that rasterizes the region of space within the range of the light sensitive sensor.

10. The method of claim 1 , further including distinguishing among the respective directionally oriented non-coplanar light sources based on different frequencies of the respective directionally oriented non-coplanar light sources.

11. The method of claim 1 , further including determining one or more angles for the returning light reflected from the target object, with respect to the sensor by mapping pixels of a camera array that captured the returning light reflected from the target object to the one or more angles.

12. The method of claim 1 ,
wherein the sensor is positioned apart from the plurality of directionally oriented non-coplanar light sources and not between any two directionally oriented non-coplanar light sources of the plurality of directionally oriented non-coplanar light sources, and
wherein the method further includes determining an angle between the plurality of directionally oriented non-coplanar light sources and the target object.

13. The method of claim 12 , further including determining a distance of the target object from the plurality of directionally oriented non-coplanar light sources or the sensor using:
an angle between at least one directionally oriented non-coplanar light source of the plurality of directionally oriented non-coplanar light sources and the target object; and
a second angle between the sensor and the target object.

14. The method of claim 1 , further including performing a plurality of scans of the region of space and varying light properties of light emitted from the respective directionally oriented non-coplanar light sources among the plurality of scans.

15. The method of claim 1 , wherein the single non-coplanar surface is at least one of:
an arc; and
an N-sided polygon.

16. The method of claim 1 , wherein the single non-coplanar surface is a parabolic curve or a hyperbolic curve.

17. The method of claim 16 , wherein the method further includes determining phase differences of the returning light reflected from the target object by applying a Fourier transform to a series of intensity measurements of the returning light reflected from the target object.

18. The method of claim 1 , wherein the scanning includes illuminating selective light emitting diodes (LEDs) of a plurality of LEDs, each LED of the plurality of LEDs being directed at a different geometric position relative to the target object.

19. The method of claim 18 , wherein the illuminating includes illuminating at least one LED, of the plurality of LEDs, directed to a different position in space relative to the target object.

20. The method of claim 18 , wherein the illuminating includes illuminating at least one LED of the plurality of LEDs directed at a different angle relative to the target object.

21. The method of claim 1 , wherein the scanning includes illuminating selective light emitting diodes (LEDs) of a plurality of LEDs, such that the target object is scanned in at least two dimensions during a single pass through the scanning.

22. A method of tracking motion of a target object for gesture control of a system by determining positional information of the target object moving in a region of space within range of a light sensitive sensor, the method including:
scanning the region of space monitored by the light sensitive sensor by selectively illuminating respective directionally oriented non-coplanar light sources of a plurality of directionally oriented non-coplanar light sources that (i) are mounted to a single non-coplanar surface and (ii) have at least some overlapping fields of illumination;
measuring, using the light sensitive sensor, one or more differences in a property of returning light emitted from the respective directionally oriented non-coplanar light sources and reflected from the target object as the target object moves through the region on space;
determining positional information of the target object based on, at least, a first position in space at a first time t 0 a

Assignees

• Leap Motion Inc

Inventors

• Holz David

Classifications

• G01S17/48

  Active triangulation systems, i.e. using the transmission and reflection of electromagnetic waves other than radio waves · CPC title

• G01S17/36 Primary

  with phase comparison between the received signal and the contemporaneously transmitted signal · CPC title

• G01S7/4815

  using multiple transmitters · CPC title

• G01S17/89

  for mapping or imaging · CPC title

• G01S7/483

  Details of pulse systems · CPC title