Method and apparatus for enhancing the detecting and tracking of moving objects using ultrasound

• US 7,894,874 B2
• Filed: 05/08/2006
• Issued: 02/22/2011
• Est. Priority Date: 05/08/2006
• Status: Expired due to Fees

• Current Assignee: Luna Innovations, Inc.
• Original Assignee: Luna Innovations, Inc.
• Inventors: Blaker, David Mark, Mack, Richard Burton Jr., Colatosti, David J., Lynch, John Edward
• Primary Examiner(s): Casler; Brian
• Assistant Examiner(s): CHAO, ELMER M
• Application Number:
  US11/429,432
• Publication Number:
  US 20100262009A1
• Time in Patent Office: 1,751 Days
• Field of Search: 600/407, 600437-461
• US Class Current: 600/407
• CPC Class Codes: A61B 8/06 Measuring blood flow measuring volume flow in general G01F, e.g. G01F1/66, G01F1/72; measuring speed of fluids in general G01P5/00
• CPC Class Codes: A61B 8/0833 involving detecting or locating foreign bodies or organic structures
• CPC Class Codes: G01S 15/8981 Discriminating between fixed and moving objects or between objects moving at different speeds, e.g. wall clutter filter
• CPC Class Codes: G01S 7/52034 Data rate converters
• CPC Class Codes: G01S 7/52036 using analysis of echo signal for target characterisation

Abstract

An ultrasonic pulse echo apparatus detects an object that is moving with respect to stationary objects. An ultrasonic transducer transmits a series of ultrasound pulses in a direction that intersects a path of the moving object. An ultrasound receiver receives a series of lines of echoes from objects in the field of view of the ultrasonic signal. Each echo line corresponds to one of the ultrasonic pulses. A signal processor processes the echo lines from the moving object. The echo lines are time shifted by different amounts and combined at different time shifts to produce different composite lines. The composite line having an optimal signal-to-noise ratio is selected. Other signal processing enhancements are performed.

Claims

1. An ultrasonic pulse echo apparatus for detecting an object that is moving with respect to a stationary object, comprising:

an ultrasound transducer for transmitting a series of ultrasound pulses in a direction that intersects a path of the moving object;

an ultrasound receiver for receiving multiple lines of echoes from the objects in the field of view of the ultrasonic signal, each echo line corresponding to one of the ultrasonic pulses; and

a signal processor for determining an envelope of each of the echo lines, time shifting the echo envelope lines different amounts, and preferentially enhancing the echoes from moving objects by combining the echo envelope lines at different time shifts and selecting one of the combined echo envelope lines with an optimal signal-to-noise ratio.

2. The apparatus in claim 1, wherein the time shifting aligns the echoes in the echo envelope lines, and wherein the signal processor is configured to determine an amplitude of each echo envelope at a particular range from the ultrasound transducer for each of the different time shifts.

3. The apparatus in claim 2, wherein the signal processor is configured to:

determine a median value or an average value of the envelope amplitudes at each time shift,

select the time shift where the envelope amplitudes have a minimum variance from the median value or average value, and

combine the echo envelope lines at the selected time shift to produce the combined echo envelope signal with the optimal signal-to-noise ratio for the particular range.

4. The apparatus in claim 2, wherein the signal processor is configured to:

determine a median value of the echo envelope amplitudes at each time shift,

select the time shift where the echo envelope amplitudes have a maximum median value, and

combine the echo envelope lines at the selected time shift to produce the combined echo envelope signal with the optimal signal-to-noise ratio for the particular range.

5. The apparatus in claim 1, wherein the signal processor is configured to sample each echo envelope signal at a reduced rate relative to higher-frequency sampling in the received echo lines required for accurate echo representation.

6. The apparatus in claim 5, wherein the reduced rate ensures that at least three sample points are contained within an envelope formed from a one-cycle ultrasonic echo.

7. The apparatus in claim 1, wherein the processor is configured to determine an envelope of each of the echo lines using a Hilbert transform and determine an envelope of each of the echo lines and remove a DC bias using a negative Hilbert transform.

8. The apparatus in claim 1, wherein the processor is configured to remove echoes associated with stationary objects that may be present in each of the echo lines.

9. The apparatus in claim 1, wherein the processor is configured to filter the combined echo envelope signal to remove one or more false peaks and to detect a peak corresponding to the moving object echo in each filtered echo envelope signal.

10. The apparatus in claim 9, wherein the processor is configured to associate the detected peak in the echo envelope line with detected peaks in successive echo envelope lines corresponding to the moving object.

11. The apparatus in claim 10, wherein the processor is configured to:

determine a track corresponding to the detected peaks in the successive echo envelope lines corresponding to the moving object,

determine how close a recently detected peak is to the track, and

update the track by adding the detected peak to the track if the recently detected peak is within a predetermined distance to the track.

12. The apparatus in claim 11, wherein the processor is configured to:

estimate a velocity and a position of the moving object based on the track.

13. The apparatus in claim 1, wherein the processor is configured to classify the moving object based on waveform characteristics of the received echoes in each line.

14. A method for detecting an object that is moving with respect to a stationary object using ultrasonic pulse echo apparatus, comprising:

using an ultrasound transmitter to transmit a series of ultrasound pulses in a direction that intersects a path of the moving object;

using an ultrasound receiver to receive multiple lines of echoes from the objects in the field of view of the ultrasonic signal, each echo line corresponding to one of the ultrasonic pulses; and

using a processor to;

determining an envelope of each of the echo lines,

time shifting the echo lines different amounts, and

preferentially enhancing the echoes from moving objects by combining the echo envelope lines at different time shifts and selecting one of the combined echo envelope lines with an optimal signal-to-noise ratio.

15. The method in claim 14, wherein the time shifting aligns the echoes in the echo envelope lines, the method further comprising:

determining an amplitude of each echo envelope at a particular range relative to the ultrasonic pulse echo apparatus for each of the different time shifts.

16. The method in claim 15, further comprising:

determining a median value or an average value of the envelope amplitudes at each time shift,

selecting the time shift where the envelope amplitudes have a minimum variance from the median value or average value, and

combining the echo envelope lines at the selected time shift to produce the combined echo envelope signal with the optimal signal-to-noise ratio for the particular range.

17. The method in claim 15, further comprising:

determining a median value of the echo envelope amplitudes at each time shift,

selecting the time shift where the echo envelope amplitudes have a maximum median value, and

combining the echo envelope lines at the selected time shift to produce the combined echo envelope signal with the optimal signal-to-noise ratio for the particular range.

18. The method in claim 15, further comprising:

sampling each echo envelope signal at a reduced rate relative to higher-frequency sampling in the received echo lines required for accurate echo representation.

19. The method in claim 18, further comprising:

setting the reduced rate to ensure that at least three sample points are contained within an envelope formed from a one-cycle ultrasonic echo.

20. The method in claim 14, further comprising:

determining an envelope of each of the echo lines using a Hilbert transform,

determining an envelope of each of the echo lines, and

removing a DC bias using a negative Hilbert transform.

21. The method in claim 14, further comprising:

removing echoes associated with stationary objects that may be present in each of the echo lines.

22. The method in claim 14, further comprising:

filtering the combined echo envelope signal to remove one or more false peaks, and

detecting a peak corresponding to the moving object echo in each filtered echo envelope signal.

23. The method in claim 22, further comprising:

associating the detected peak in the echo envelope line with detected peaks in successive echo envelope lines corresponding to the moving object.

24. The method in claim 23, further comprising:

determining a track corresponding to the detected peaks in the successive echo envelope lines corresponding to the moving object,

determining how close a recently detected peak is to the track, and

updating the track by adding the detected peak to the track if the recently detected peak is within a minimum distance threshold to the track.

25. The method in claim 24, further comprising:

estimating a velocity and a position of the moving object based on the track.

26. The method in claim 14, further comprising:

classifying the moving object based on waveform characteristics of the received echoes in each line.

27. An ultrasonic pulse echo apparatus for detecting an object that is moving with respect to a stationary object and subjected to a sequence of ultrasound pulses that intersect a path of the moving object, comprising:

an ultrasound receiver for receiving multiple lines of echoes from the objects in the field of view of the ultrasonic signal, each echo line corresponding to one of the ultrasonic pulses; and

processing circuitry for preferentially enhancing the echoes from moving objects and configured to;

time shift the echo lines different amounts,

determine an amplitude of each echo line at a particular range from the ultrasound pulse echo apparatus for different time shifts,

combine the echo lines at different time shifts,

determine a median value or an average value of the echo lines amplitudes at different time shifts, and

select the time shift where the echo amplitudes have a minimum variance from the median value or average value.

28. The apparatus in claim 27, wherein the processing circuitry is configured to sample each echo signal at a reduced rate relative to higher-frequency sampling in the received echo lines required for accurate echo representation.

29. The apparatus in claim 28, wherein the reduced rate ensures that at least three sample points for a one-cycle ultrasonic echo.

30. An ultrasonic pulse echo apparatus for detecting an object that is moving with respect to a stationary object and subjected to a sequence of ultrasound pulses that intersect a path of the moving object, comprising:

an ultrasound receiver for receiving multiple lines of echoes from the objects in the field of view of the ultrasonic signal, each echo line corresponding to one of the ultrasonic pulses; and

processing circuitry for preferentially enhancing the echoes from moving objects, determining a track corresponding to detected echoes in successive echo lines corresponding to the moving object, determining how close a recently detected echo is to the track, and updating the track by adding the detected echo to the track if the recently detected echo is within a minimum distance threshold to the track.

31. The apparatus in claim 30, wherein the processor is configured to estimate a velocity and a position of the moving object based on the track.