ACOUSTIC MOTION DETERMINATION

• US 20120243374A1
• Filed: 09/22/2010
• Published: 09/27/2012
• Est. Priority Date: 09/23/2009
• Status: Active Grant

• Current Assignee: Elliptic Laboratories AS
• Original Assignee: Elliptic Laboratories AS
• Inventors: Dahl, Tobias, Kavli, Tom Øystein, Kirkhus, Trine
• Granted Patent: US 9,152,276 B2
• Time in Patent Office: Days
• US Class Current: 367/93
• CPC Class Codes: G06F 2203/04101 2.5D-digitiser, i.e. digitiser detecting the X/Y position of the input means, finger or stylus, also when it does not touch, but is proximate to the digitiser's interaction surface and also measures the distance of the input means within a short range in the Z direction, possibly with a separate measurement setup
• CPC Class Codes: G06F 3/043 using propagating acoustic waves

Abstract

The motion of an object is characterised by transmitting acoustic signals over first and second transmitter-receiver channels. Information relating to signals received over the first channel is compared with information relating to signals received over the second channel, to identify a similar pattern in both channels arising from reflections from the object. A relative timing difference between the channels, associated with the similar pattern, is used to characterise the motion of the object.

Claims

1. A method of characterising the motion of an object comprising:

continuously or discretely transmitting acoustic transmit signals over first and second channels, each channel comprising at least one transmitter and at least one receiver, wherein the received signals on each channel comprise reflections from the object;

comparing information relating to signals received over the first channel with information relating to signals received over the second channel to identify a similar pattern in both channels arising from reflections from the object; and

using one or more relative timing differences between the channels, associated with the similar pattern, to characterise the motion of the object.

2. The method of claim 1 wherein the similar pattern spans a plurality of transmit signals.

3. The method of claim 1, further comprising using the motion characterisation to control an electronic device.

4. The method of claim 1 comprising processing one or more of the received signals using one or more processes selected from the group consisting of:

amplification, sampling, analogue filtering, digital filtering, envelope extraction, distortion in time, linear transformation, non-linear transformation, complex transformation, frequency-domain transformation, and time-frequency-domain transformation.

5. The method of claim 1 wherein the similar pattern occurs within a first time window in the first channel and within a second time window in the second channel, comprising using the temporal offset between the first and second time windows to characterise the motion of the object.

6. The method of claim 5 wherein the temporal offset between the first and second time windows is greater than a minimum amount selected from the group consisting of:

0.5 milliseconds;

1 millisecond;

1.5 milliseconds;

the time it takes a signal to travel to an object at the periphery of a predetermined detection range;

the time it takes a signal to travel to and from an object at the periphery of a predetermined detection range;

the maximum time-of-flight difference between the two channels for a given signal; and

, for periodic transmit signals, the period of the transmit signals or a multiple of said period.

7. The method of claim 1 wherein the transmit signals are periodic.

8. The method of claim 1 wherein the transmit signals are composed of a series of pulses.

9. The method of claim 1 wherein the transmit signals comprise one or more chirps.

10. The method of claim 1, further comprising calculating an impulse response.

11. The method of claim 1, further comprising comparing the envelope of received signals collected during first and second time windows in the respective first and second channels.

12. The method of claim 1, further comprising comparing information relating to received signals arising from a plurality of successive transmit signals on the first channel with information relating to received signals arising from a plurality of successive transmit signals on the second channel.

13. The method of claim 1 wherein at least some of the transmit signals from which the similar pattern in one channel arises are transmitted earlier than the transmit signals from which the similar pattern in the other channel arises.

15. The method of claim 1 wherein the comparison step is carried out on at least a portion of a filtered signal.

16. The method of claim 1, further comprising transmitting acoustic transmit signals over more than two channels, each channel comprising at least one transmitter and at least one receiver, wherein the received signals on each channel comprise reflections from the object.

17. The method of claim 1, further comprising transmitting acoustic transmit signals from a plurality of transmitters wherein the transmit signal is encoded differently for each transmitter.

18. The method of claim 1, further comprising calculating a variance parameter between two sets of values arising from reflections from the object, and applying a threshold variance to determine whether two patterns from different channels are similar or not.

19. The method of claim 1, further comprising performing a cross-correlation between sets of values arising from reflections from the object.

20. The method of claim 1 wherein the similar pattern in one channel is a transformation of the similar pattern in the other channel.

21. The method of claim 1, further comprising applying a transformation to information relating to signals received in one or both channels before making an identification of a similar pattern.

22. The method of claim 1, further comprising dithering the transmit signals in time, and applying an inverse dithering to the received signals.

23. The method of claim 1 wherein the patterns comprise intensity contours in response images.

24. The method of claim 1, further comprising applying one or more filters to the received signals selected from the set of filters consisting of:

filters that pass signals corresponding to a set of trajectories of motion of the object;

filters to enhance a motion trend in the received signals;

filters to detect motion of the object in the presence of noise;

filters to remove contributions from slowly-moving objects;

filters to remove contributions from still objects;

filters to remove contributions where it can be determined that two objects are overlapping in time-of-flight distance;

response image edge filters; and

Constant False Alarm Rate filters.

25. The method of claim 1 wherein portions of the received signals that do not include reflections from the object of interest are excluded from the comparison step.

14. (canceled)

26. Apparatus for characterising the motion of an object comprising:

a transmission subsystem arranged to transmit acoustic signals;

a receiving subsystem arranged to receive signals and, with the transmission subsystem, defining first and second channels, wherein the received signals on each channel comprise reflections from the object; and

a processing subsystem configured to compare information relating to signals received over the first channel with information relating to signals received over the second channel to identify a similar pattern in both channels arising from reflections from the object; and

to use one or more relative timing differences between the channels, associated with the similar pattern, to characterise the motion of the object.

27. The apparatus of claim 26 wherein the transmission and receiving subsystems define more than two channels.

28. The apparatus of claim 26 comprising at least one transmitter that is shared by a plurality of channels.

29. The apparatus of claim 26 comprising at least one receiver that is shared by a plurality of channels.

30. A computer software product configured, when run on a computer, to characterise the motion of an object comprising:

instructions for continuously or discretely transmitting acoustic transmit signals over first and second channels, each channel comprising at least one transmitter and at least one receiver, wherein the received signals on each channel comprise reflections from the object;

logic for comparing information relating to signals received over the first channel with information relating to signals received over the second channel to identify a similar pattern in both channels arising from reflections from the object; and

logic for using one or more relative timing differences between the channels, associated with the similar pattern, to characterise the motion of the object.

31-80. -80. (canceled)