Proximity sensing systems and methods

• US 9,223,023 B2
• Filed: 08/19/2014
• Issued: 12/29/2015
• Est. Priority Date: 04/11/2014
• Status: Active Grant

• Current Assignee: SZ DJI Technology Co., Ltd. (d/b/a DJI) (iFlight Technology Company Limited)
• Original Assignee: SZ DJI Technology Co., Ltd. (d/b/a DJI) (iFlight Technology Company Limited)
• Inventors: Zhou, Wancheng, Huang, Liming
• Primary Examiner(s): Martin, Laura
• Assistant Examiner(s): MILLER, ROSE MARY
• Application Number:
  US14/463,578
• Publication Number:
  US 20150292879A1
• Time in Patent Office: 497 Days
• Field of Search: 736/02
• US Class Current: 1/1
• CPC Class Codes: G01B 17/00 Measuring arrangements characterised by the use of infrasonic, sonic or ultrasonic vibrations
• CPC Class Codes: G01S 15/93 for anti-collision purposes
• CPC Class Codes: G01S 15/931 of land vehicles
• CPC Class Codes: G01S 7/524 Transmitters
• CPC Class Codes: G01S 7/527 Extracting wanted echo signals Doppler systems G01S15/50
• CPC Class Codes: G01S 7/5273 using digital techniques
• CPC Class Codes: G01S 7/529 Gain of receiver varied automatically during pulse-recurrence period for seismic signals G01V1/245

Abstract

Methods, systems and device are provided for improving the range and accuracy of proximity measurement such as in ultrasonic sensing systems. In particular, the blind zone caused by reverberation signals can be reduced or eliminated by attenuating signals received during the time period corresponding to the blind zone without. In an implementation, an attenuator circuit is selected by a switch to process received signals during the blind zone time period and deselected by the switch after the time zone time period. Additionally, the accuracy and range of the measurement can be improved by varying the gain provided to the received signals based on the varying measuring distance. In an implementation, a gain-adjustable amplifier is controlled by a gain control signal to provide incremental gain as time increases.

Claims

1. An ultrasonic sensing system, comprising:

an ultrasonic transmitter configured to provide a transmission of ultrasonic signals;

an ultrasonic receiver configured to receive ultrasonic signals generated as a result of the transmission including reverberation signals and echo signals;

an attenuator circuit connectable to the ultrasonic receiver via a switch, the attenuator circuit operable for attenuating the received ultrasonic signals; and

a microcontroller unit (MCU) configured to control the switch to electrically couple the ultrasonic receiver with the attenuator circuit during a predetermined period of time after the transmission of ultrasonic signals and electrically decouple the ultrasonic receiver from the attenuator circuit prior to and after the predetermined period of time.

2. The system of claim 1, wherein the ultrasonic transmitter is the ultrasonic receiver.

3. The system of claim 1, wherein the predetermined period of time corresponds to a blind zone time period for the ultrasonic sensing system.

4. The system of claim 1, wherein the attenuator circuit is configured to provide an amount of attenuation selected based at least in part on a previously-measured amplitude of a reverberation signal or an echo signal.

5. The system of claim 1, further comprising a booster coupled to the ultrasonic transmitter and configured to increase an energy level associated with the transmission of ultrasonic signals.

6. The system of claim 1, further comprising a gain-adjustable amplifier coupled to the ultrasonic receiver and configured to amplify the echo signals.

7. The system of claim 6, wherein the MCU is further configured to control the gain-adjustable amplifier to vary its gain based at least in part on a value of a timer that corresponds to a measuring distance.

8. The system of claim 7, wherein the MCU is further configured to control the gain-adjustable amplifier to vary its gain based at least in part on previously-measured data.

9. The system of claim 6, wherein the MCU is further configured to control the switch to electrically couple the ultrasonic receiver with the gain-adjustable amplifier without electrically coupling the attenuator circuit with the gain-adjustable amplifier after the predetermined period of time has elapsed.

10. The system of claim 6, further comprising a comparator connected to the gain-adjustable amplifier that is configured to compare an output of the gain-adjustable amplifier with a predetermined threshold value.

11. The system of claim 10, wherein the comparator is integrated with the MCU.

12. The system of claim 10, further comprising an analog-to-digital converter (ADC) connected to the gain-adjustable amplifier that is configured to convert the output of the gain-adjustable amplifier to a digital value.

13. The system of claim 12, wherein the comparator and the ADC are used in conjunction to determine an occurrence of a peak amplitude of a received ultrasonic signal.

14. A method for ultrasonic sensing, comprising:

detecting, with aid of an ultrasonic receiver, a signal after termination of a transmission of ultrasonic signals, wherein the detected signal is an echo signal or a reverberation signal;

determining whether the detection of the ultrasonic signal occurs within a predetermined period of time from the termination of the transmission of ultrasonic signals;

in response to a determination that the detection of the signal occurs within the predetermined period of time, attenuating, with aid of an attenuator circuit, the detected signal to sufficiently reduce interference caused by reverberation from the transmission of the ultrasonic signals;

electrically decoupling the ultrasonic receiver from the attenuator circuit when the predetermined period of time has elapsed; and

in response to a determination that the detection of the signal occurs after the predetermined period of time has elapsed, processing, without attenuating, the detected signal to determine proximity of an object.

15. The method of claim 14, wherein the predetermined period of time corresponds to a blind zone time period.

16. The method of claim 14, wherein attenuating the detected ultrasonic signal is based at least in part on one or more previously-measured signals.

17. The method of claim 14, wherein processing the detected ultrasonic signal includes determining occurrence of a peak amplitude using a comparator and an analog-to-digital converter (ADC).

18. The method of claim 14, further comprising providing a gain to the detected ultrasonic signal based at least in part on previously-measured data that correlates a measuring distance and a gain suitable for the measuring distance.

19. The method of claim 14, further comprising providing a gain to the detected ultrasonic signal based at least in part on a timer value.

20. An ultrasonic sensing system, comprising:

an ultrasonic transmitter configured to provide a transmission of ultrasonic signals;

an ultrasonic receiver configured to receive ultrasonic signals generated as a result of the transmission including reverberation signals and echo signals;

an attenuator circuit connectable to the ultrasonic receiver via a switch, the attenuator circuit operable for attenuating the received ultrasonic signals; and

a microcontroller unit (MCU) configured to control the switch to electrically couple the ultrasonic receiver with the attenuator circuit only during a predetermined period of time after the transmission of ultrasonic signals;

a comparator connected to a gain-adjustable amplifier connected to the ultrasonic receiver; and

an analog-to-digital converter (ADC) connected to the gain-adjustable amplifier,

wherein the comparator and the ADC are configured to be used in conjunction to determine an occurrence of a peak amplitude of a received ultrasonic signal.

21. The system of claim 20, wherein the ultrasonic transmitter is the ultrasonic receiver.

22. The system of claim 20, wherein the predetermined period of time corresponds to a blind zone time period for the ultrasonic sensing system.

23. The system of claim 20, wherein the attenuator circuit is configured to provide an amount of attenuation selected based at least in part on a previously-measured amplitude of a reverberation signal or an echo signal.

24. A method for ultrasonic sensing, comprising:

detecting a signal after termination of a transmission of ultrasonic signals, the detected signal can be an echo signal or a reverberation signal;

determining whether the detection of the ultrasonic signal occurs within a predetermined period of time from the terminal of the transmission of ultrasonic signals;

in response to a determination that the detection of the signal occurs within the predetermined period of time, attenuating the detected signal to sufficiently reduce interference caused by reverberation from the transmission of the ultrasonic signals; and

in response to a determination that the detection of the signal occurs after the predetermined period of time has elapsed, processing, without attenuating, the detected signal to determine proximity of an object,

wherein processing the detected ultrasonic signal includes determining occurrence of a peak amplitude using a comparator and an analog-to-digital converter (ADC).

25. The method of claim 24, wherein attenuating the detected ultrasonic signal is based at least in part on one or more previously-measured signals.