Obstacle monitoring using motion-compensated distance
An obstacle monitoring system includes a first transducer that obtains a first distance measurement to an obstacle using a first linear frequency modulated (“LFM”) chirp. The system further includes a second transducer, able to operate concurrently with the first transducer, that obtains a second distance measurement to the obstacle using a second LFM chirp. The second LFM chirp has an inverted slope or shifted center frequency compared to the first LFM chirp. The system further includes a controller that processes the first and second distance measurements to determine a motion-compensated distance measurement to the obstacle.
1. An obstacle monitoring system comprising:
a first transducer that obtains a first distance measurement to an obstacle using a first linear frequency modulated (“LFM”) chirp;
a second transducer that operates concurrently with the first transducer, the second transducer obtaining a second distance measurement to the obstacle using a second LFM chirp, the second LFM chirp having an inverted slope or shifted center frequency compared to the first LFM chirp; and
a controller that processes the first and second distance measurements to determine a motion-compensated distance measurement to the obstacle.
2. The system of claim 1 , wherein the controller differences the first and second distance measurements to measure a motion of the obstacle.
3. The system of claim 2 , wherein the motion of the obstacle comprises approaching or receding relative to the first and second transducer.
4. The system of claim 2 , wherein the motion of obstacle comprises a relative speed of the obstacle compared to the first or second transducer.
5. The system of claim 4 , wherein the controller compensates the first or second distance measurement based on the relative speed.
6. The system of claim 1 , wherein the controller adjusts subsequent chirps based on minimum detection distance, maximum detection distance, signal-to-noise ratio, channel separation, time-of-flight accuracy, time-of-flight resolution, or transducer bandwidth.
7. The system of claim 6 , wherein the controller adjusts chirp duration.
8. The system of claim 6 , wherein the controller adjusts chirp bandwidth.
9. The system of claim 6 , wherein the controller adjusts chirp center frequency.
10. The system of claim 1 , wherein the first and second LFM chirps are transmitted on separate channels.
11. The system of claim 1 , wherein the absolute values of the slopes of the first and second LFM chirps are equal.
12. An obstacle monitoring method comprising:
transmitting a first linear frequency modulated (“LFM”) chirp;
determining a first distance measurement to an obstacle based on a response to the first LFM chirp;
transmitting a second LFM chirp, the second LFM chirp having an inverted slope or shifted center frequency compared to the first LFM chirp;
determining a second distance measurement to the obstacle based on a response to the second LFM chirp; and
processing the first and second distance measurements to determine a motion-compensated distance measurement to the obstacle.
13. The method of claim 12 , further comprising differencing the first and second distance measurements to measure a motion of the obstacle.
14. The method of claim 13 , wherein the motion of the obstacle comprises approaching or receding relative to a transducer.
15. The method of claim 13 , wherein the motion of obstacle comprises a relative speed of the obstacle.
16. The method of claim 15 , further comprising compensating the first or second distance measurement based on the relative speed.
17. The method of claim 12 , further comprising adjusting subsequent LFM chirps based on minimum detection distance, maximum detection distance, signal-to-noise ratio, channel separation, time-of-flight accuracy, time-of-flight resolution, or transducer bandwidth.
18. The method of claim 12 , wherein the transmitting the second LFM chirp comprises transmitting the second LFM chirp on a separate channel from the first LFM chirp.
19. The method of claim 12 , wherein the absolute values of the slopes of the first and second LFM chirps are equal.
20. A non-transitory computer-readable medium comprising instructions that, when executed, cause one or more processors to:
obtain a first distance measurement to an obstacle using a first linear frequency modulated (“LFM”) chirp;
obtain a second distance measurement to the obstacle using a second LFM chirp, the second LFM chirp having an inverted slope or shifted center frequency compared to the first LFM chirp; and
process the first and second distance measurements to determine a motion-compensated distance measurement to the obstacle.