Radar-image shaper for radar-based applications
This document describes techniques and systems that enable a radar-image shaper for radar-based applications. A radar field enables an electronic device to accurately determine a characteristic disposition (e.g., a location, orientation, velocity, or direction) of an object in the radar field. The characteristic disposition is determined by detecting a radar cross-section (or radar signature) of a radar-image shaper that is included in the object. The shape of the radar-image shaper produces a known signature when illuminated by the radar field. Using these techniques, the electronic device can determine a characteristic disposition of the object, which allows the object to be used to interact with the electronic device using gestures and other position-based techniques. Because the radar-image shaper enables a passive object to control applications on the electronic device, users have an interaction method with a rich library of gestures and controls that does not require additional components or a battery.
1. An electronic device, comprising:
a radar system, implemented at least partially in hardware, configured to:
provide a radar field;
sense reflections from an object in the radar field;
analyze the reflections from the object in the radar field; and
provide, based on the analysis of the reflections, radar data;
one or more computer processors; and
one or more computer-readable media having instructions stored thereon that, responsive to execution by the one or more computer processors, implement a radar-signature manager configured to:
detect, based on a first subset of the radar data, a radar signature of a radar-image shaper that is attached to the object in the radar field;
compare the detected radar signature to a benchmark radar signature that corresponds to a characteristic disposition of the radar-image shaper, the comparison comprising to:
determine features of the radar-image shaper based on the first subset of the radar data; and
analyze the determined features to determine a match to known features of the benchmark radar signature;
determine, based on the comparison, that the detected radar signature matches the benchmark radar signature; and
responsive to the determination that the detected radar signature matches the benchmark radar signature, determine, based on the characteristic disposition of the radar-image shaper that corresponds to the matched benchmark radar signature, a characteristic disposition of the object in the radar field.
2. The electronic device of claim 1 , wherein the radar-signature manager is further configured to:
determine, based on a second subset of the radar data, a change in the characteristic disposition of the object in the radar field;
based on the change in the characteristic disposition of the object in the radar field, determine a gesture by the object in the radar field;
determine a function of the electronic device that corresponds to the gesture; and
cause the electronic device to provide the function.
3. The electronic device of claim 1 , wherein the radar-signature manager is further configured to compare the detected radar signature to the benchmark radar signature by comparison of the detected radar signature to a plurality of benchmark radar signatures, each benchmark radar signature of the plurality of radar signature corresponding to a different characteristic disposition of the radar-image shaper.
4. The electronic device of claim 1 , wherein the radar-image shaper is a corner reflector.
5. The electronic device of claim 4 , wherein the corner reflector is an octahedron comprising eight trihedral corner reflectors.
6. The electronic device of claim 1 , wherein the radar-image shaper is asymmetrical.
7. The electronic device of claim 1 , wherein:
the radar-image shaper comprises a first portion made from a first material and a second portion made from a second material;
the first material absorbs radar signals within a first range of frequencies; and
the second material absorbs radar signals within a second range of frequencies, at least a part of the second range of frequencies not included in the first range of frequencies.
8. The electronic device of claim 1 , wherein a length of a longest edge of the radar-image shaper is between 1 millimeter and ten millimeters.
9. The electronic device of claim 1 , wherein the radar system further comprises a digital beamformer and an angle estimator, and the radar system is configured to monitor angles in a field of view between approximately −90 degrees and approximately 90 degrees.
10. The electronic device of claim 1 , wherein the characteristic disposition of the radar-image shaper includes one or more of:
an orientation of the radar-image shaper with respect to the radar system;
a location of the radar-image shaper with respect to the radar system;
a velocity of the radar-image shaper; or
a direction of a movement of the radar-image shaper.
11. A method implemented by an electronic device that includes a radar system, the method comprising:
providing, by the radar system, a radar field;
sensing, by the radar system, reflections from an object in the radar field;
analyzing the reflections from the object in the radar field;
providing, based on the analysis of the reflections, radar data;
detecting, based on a first subset of the radar data, a radar signature of a radar-image shaper that is attached to the object in the radar field;
comparing the detected radar signature to a benchmark radar signature, the benchmark radar signature corresponding to a characteristic disposition of the radar-image shaper, the comparison comprising:
determining features of the radar-image shaper based on the first subset of the radar data; and
analyzing the determined features to determine a match to known features of the benchmark radar signature;
determining, based on the comparison, that the detected radar signature matches the benchmark radar signature; and
responsive to determining that the detected radar signature matches the benchmark radar signature, determining a characteristic disposition of the object in the radar field, based on the characteristic disposition of the radar-image shaper that corresponds to the matched benchmark radar signature.
12. The method of claim 11 , further comprising:
determining, based on a second subset of the radar data, a change in the characteristic disposition of the object in the radar field;
determining, based on the change in the characteristic disposition of the object in the radar field, a gesture by the object in the radar field;
determining a function of the electronic device that corresponds to the gesture; and
causing the electronic device to provide the function.
13. The method of claim 11 , wherein comparing the detected radar signature to the benchmark radar signature further comprises comparing the detected radar signature to a plurality of benchmark radar signatures, each benchmark radar signature of the plurality of radar signatures corresponding to a different characteristic disposition of the radar-image shaper.
14. The method of claim 11 , wherein the characteristic disposition of the radar-image shaper includes one or more of:
an orientation of the radar-image shaper with respect to the radar system;
a location of the radar-image shaper with respect to the radar system;
a velocity of the radar-image shaper; or
a direction of a movement of the radar-image shaper.
15. A stylus, comprising:
a stylus housing; and
a radar-image shaper integrated with the stylus housing, the radar-image shaper configured to provide a radar signature that is detectable by a radar system, the radar signature effective to enable the radar system to determine a characteristic disposition of the housing, the determination of the characteristic disposition of the housing comprising:
detecting the radar signature of the radar-image shaper;
comparing the detected radar signature to a benchmark radar signature, the benchmark radar signature corresponding to a characteristic disposition of the radar-image shaper, the comparison comprising:
determining features of the radar-image shaper, based on the radar signature; and
analyzing the determined features to determine a match to known features of the benchmark radar signature;
determining, based on the comparison, that the detected radar signature matches the benchmark radar signature; and
responsive to determining that the detected radar signature matches the benchmark radar signature, determining a characteristic disposition of the housing based on the characteristic disposition of the radar-image shaper that corresponds to the matched benchmark radar signature.
16. The stylus of claim 15 , further comprising another radar-image shaper, and wherein:
the radar-image shaper is integrated nearer to a first end of the housing; and
the other radar-image shaper is integrated nearer to a second end of the housing.
17. The stylus of claim 16 , wherein the radar-image shaper and the other radar-image shaper are made from different materials.
18. The stylus of claim 16 , wherein the radar-image shaper and the other radar-image shaper are different shapes.
19. The stylus of claim 15 , wherein the housing has a cross-section that is cylindrical or elliptical.
20. The stylus of claim 15 , wherein the characteristic disposition of the radar-image shaper includes one or more of:
an orientation of the radar-image shaper with respect to the radar system;
a location of the radar-image shaper with respect to the radar system;
a velocity of the radar-image shaper; or
a direction of a movement of the radar-image shaper.