Object detection system

Patent metadata

Field	Value
Publication number	US-12326501-B2
Application number	US-202318215328-A
Country	US
Kind code	B2
Filing date	Jun 28, 2023
Priority date	Mar 3, 2021
Publication date	Jun 10, 2025
Grant date	Jun 10, 2025

Abstract

An object detection system includes a processing circuit to perform wave transmission processing and determination processing. In the wave transmission processing, an acoustic wave generator is controlled to generate a series of acoustic waves of a time-varying frequency at target sound pressures associated with a frequency and correspond to the respective acoustic waves. In the determination processing, a received-wave signal representing an acoustic wave from a target space received by a wave receiver is acquired and it is determined whether an object is present in the target space based on the received-wave signal. Each of the target sound pressures is set based on the frequency characteristics of sensitivity of the wave receiver to an acoustic wave of a predetermined sound pressure, such that the sensitivity of the wave receiver to an acoustic wave of the target sound pressure is in a predetermined range including a predetermined value.

First claim

What is claimed is:

1. An object detection system comprising:
an acoustic wave generator to generate an acoustic wave by generating heat upon energization; and
a processing circuit to perform object detection processing to detect an object in a target space using an acoustic wave from the acoustic wave generator; wherein
the object detection processing includes:
wave transmission processing in which the acoustic wave generator is controlled to generate a series of acoustic waves of a time-varying frequency at target sound pressures that are associated with a frequency and correspond to the respective acoustic waves; and
determination processing in which a received-wave signal representing an acoustic wave received by a wave receiver to receive an acoustic wave from the target space is acquired from the wave receiver and it is determined whether the object is present in the target space based on the received-wave signal;

each of the target sound pressures is set, based on frequency characteristics of sensitivity of the wave receiver to an acoustic wave of a predetermined sound pressure, such that sensitivity of the wave receiver to an acoustic wave of the target sound pressure is in a predetermined range including a predetermined value;
a frequency of the series of acoustic waves varies in a predetermined frequency range; and
the predetermined value is a maximum value of the sensitivity of the wave receiver to an acoustic wave of a predetermined sound pressure in the predetermined frequency range.

2. The object detection system according to claim 1 , wherein
an upper limit of the predetermined range is greater than or equal to the predetermined value; and
a median value of the predetermined range is less than or equal to the predetermined value.

3. The object detection system according to claim 1 , wherein a lower limit of the predetermined range is less than or equal to the predetermined value and is greater than a minimum value of the sensitivity of the wave receiver to an acoustic wave of a predetermined sound pressure in the predetermined frequency range.

4. The object detection system according to claim 3 , wherein an upper limit of the predetermined range is the predetermined value.

5. The object detection system according to claim 3 , wherein a target sound pressure of an acoustic wave of a frequency at which the sensitivity of the wave receiver to an acoustic wave of a predetermined sound pressure is less than the predetermined value is higher than the predetermined sound pressure.

6. The object detection system according to claim 1 , wherein the predetermined range is a range of about +10% of the predetermined value.

7. An object detection system comprising:
an acoustic wave generator to generate an acoustic wave by generating heat upon energization; and
a processing circuit to perform object detection processing to detect an object in target space using an acoustic wave from the acoustic wave generator; wherein
the object detection processing includes:
wave transmission processing in which the acoustic wave generator is controlled to generate a series of acoustic waves of a time-varying frequency at target sound pressures that are associated with a frequency and correspond to the respective acoustic waves; and
determination processing in which a received-wave signal representing an acoustic wave received by a wave receiver to receive an acoustic wave from the target space is acquired from the wave receiver and it is determined whether the object is present in the target space based on the received-wave signal;

a frequency of the series of acoustic waves varies in a predetermined frequency range;
each of the target sound pressures is set, based on frequency characteristics of sensitivity of the wave receiver to an acoustic wave of a predetermined sound pressure, such that sensitivity of the wave receiver to an acoustic wave of the target sound pressure coincides with a predetermined value; and
the predetermined value is a maximum value of the sensitivity of the wave receiver to an acoustic wave of a predetermined sound pressure in the predetermined frequency range.

8. The object detection system according to claim 1 , wherein, in the determination processing, it is determined that the object is present when a peak value of a cross-correlation function between a transmitted-wave signal representing the series of acoustic waves and the received-wave signal is greater than a threshold value.

9. The object detection system according to claim 7 , wherein, in the determination processing, it is determined that the object is present when a peak value of a cross-correlation function between a transmitted-wave signal representing the series of acoustic waves and the received-wave signal is greater than a threshold value.

10. The object detection system according to claim 1 , wherein
the acoustic wave generator includes:
a driving circuit including a capacitor charged by a direct-current power supply and a driving switch to supply power from the capacitor to an acoustic wave source to generate an acoustic wave by generating heat upon energization; and
an adjustment circuit to adjust a sound pressure of an acoustic wave to be output from the acoustic wave generator by adjusting a voltage across the capacitor in the driving circuit; and

in the wave transmission processing:
the adjustment circuit is operable to adjust a voltage across the capacitor such that a sound pressure of an acoustic wave to be output from the acoustic wave generator becomes the target sound pressure; and
the driving switch in the driving circuit is operable to be driven to cause the acoustic wave source to generate an acoustic wave.

11. The object detection system according to claim 10 , wherein
the adjustment circuit includes:
an inductor electrically connected between the direct-current power supply and the capacitor; and
an adjustment switch electrically connected in parallel to a series circuit of the inductor and the direct-current power supply; and

the adjustment circuit is operable to adjust a voltage across the capacitor in an ON period of the adjustment switch.

12. The object detection system according to claim 11 , wherein
the adjustment circuit includes a diode;
an anode of the diode is electrically connected to the inductor; and
a cathode of the diode is electrically connected to the capacitor.

13. The object detection system according to claim 11 , wherein the adjustment switch is in an ON state in an ON period of the driving switch and is turned on simultaneously with the driving switch.

14. The object detection system according to claim 7 , wherein
the acoustic wave generator includes:
a driving circuit including a capacitor charged by a direct-current power supply and a driving switch to supply power from the capacitor to an acoustic wave source to generate an acoustic wave by generating heat upon energization; and
an adjustment circuit to adjust a sound pressure of an acoustic wave to be output from the acoustic wave generator by adjusting a voltage across the capacitor in the driving circuit; and

in the wave transmission processing:
the adjustment circuit is operable to adjust a voltage across the capacitor such that a sound pressure of an acoustic wave to be output from the acoustic wave generator becomes the target sound pressure; and
the driving switch in the driving circuit is operable to be driven to cause the acoustic wave source to generate an acoustic wave.

15. The object detection system according to claim 14 , wherein
the adjustment circuit includes:
an inductor

Assignees

• Murata Manufacturing Co

Inventors

• Sasaki Shinichi
• Asada Takaaki

Classifications

• G01S2007/52007

  involving adjustment of transmitted power · CPC title

• G01S7/526

  Receivers · CPC title

• G01S7/52004

  Means for monitoring or calibrating (short-range imaging G01S7/5205) · CPC title

• G01S7/521

  Constructional features · CPC title

• G01S15/104

  wherein the transmitted pulses use a frequency- or phase-modulated carrier wave · CPC title