Apparatus and method of vehicle occupant sensing using multiple ultrasonic frequencies

• US 6,563,761 B1
• Filed: 11/02/2000
• Issued: 05/13/2003
• Est. Priority Date: 11/02/2000
• Status: Expired due to Fees

• Current Assignee: TRW Limited (Zeppelin - Stiftung der Stadt Friedrichshafen)
• Original Assignee: TRW Limited (Zeppelin - Stiftung der Stadt Friedrichshafen)
• Inventors: McKim, Dale W., Schaffran, Michelle R., Cooper, Stephen R. W., Gillis, Edward J.
• Primary Examiner(s): Lobo, Ian J.
• Application Number:
  US09/704,995
• Time in Patent Office: 922 Days
• Field of Search: 280/735, 367/99, 367/101, 701/45, 701/47
• US Class Current: 367/101
• CPC Class Codes: B60N 2/002 Seats provided with an occupancy detection means mounted therein or thereon detection means responsive to presence or absence of children B60N2/266
• CPC Class Codes: G01S 15/107 using frequency agility of carrier wave
• CPC Class Codes: G01S 15/87 Combinations of sonar systems
• CPC Class Codes: G01S 15/88 Sonar systems specially adapted for specific applications seismic or acoustic prospecting or detecting G01V1/00
• CPC Class Codes: G01S 7/527 Extracting wanted echo signals Doppler systems G01S15/50

Abstract

An apparatus (20) determines a vehicle occupant location characteristic. The apparatus (20) includes at least one sensor (e.g., 46) for echo ranging at first and second ultrasonic frequencies. A timer function portion (84) of a microcomputer (66) determines a time-of-flight for each frequency signal. The microcomputer (66) determines the occupant location characteristic using at least one of the determined times-of-flight.

Claims

1. An apparatus for determining a vehicle occupant location characteristic, said apparatus comprising:

means for echo ranging at a first ultrasonic frequency to determine a first time-of-flight to an occupant seating position;

means for echo ranging at a second ultrasonic frequency, different from said first ultrasonic frequency, to determine a second time-of-flight to the occupant seating position; and

means for determining the occupant location characteristic using at least one of the determined times-of-flight,

said means for echo ranging at the first frequency including means for emitting a first ultrasonic signal at the first frequency toward the occupant seating position, means for receiving a return echo of the first signal, and means for determining time duration between emission of the first signal and reception of the first signal echo, and said means for echo ranging at the second frequency including means for emitting a second ultrasonic signal at the second frequency toward the occupant seating position, means for receiving a return echo of the second signal, and means for determining time duration between emission of the second signal and reception of the second signal echo,

said means for emitting the first ultrasonic signal including a transducer operating at a resonant frequency of said transducer, the resonant frequency being the first frequency, and said means for emitting the second ultrasonic signal including said transducer operating at a first harmonic frequency of said transducer, the first harmonic frequency being the second frequency.

2. A method for determining a vehicle occupant location characteristic, said method comprising the steps of:

echo ranging at a first ultrasonic frequency to determine a first time-of-flight to an occupant seating position;

echo ranging at a second ultrasonic frequency, different from said first ultrasonic frequency, to determine a second time-of-flight to the occupant seating position; and

determining the occupant location characteristic using at least one of the determined times-of-flight,

wherein said step of echo ranging at the first frequency includes emitting a first ultrasonic signal at the first frequency toward the occupant seating position, receiving a return echo of the first signal, and determining time duration between emission of the first signal and reception of the first signal echo, and said step of echo ranging at the second frequency includes emitting a second ultrasonic signal at the second frequency toward the occupant seating position, receiving a return echo of the second signal, and determining time duration between emission of the second signal and reception of the second signal echo, and

wherein said step of emitting the first ultrasonic signal includes operating a transducer at a resonant frequency of the transducer, the resonant frequency being the first frequency, and said step of emitting the second ultrasonic signal includes operating the transducer at a first harmonic frequency of the transducer, the first harmonic frequency being the second frequency.

3. A method as set forth in claim 2, wherein said step of echo ranging at the first ultrasonic frequency includes emitting a first ultrasonic signal at the first ultrasonic frequency toward the occupant seating position, receiving a first return echo of the first ultrasonic signal, and determining time duration between emission of the first ultrasonic signal and reception of the first return echo, and said step of echo ranging at the second ultrasonic frequency includes emitting a second ultrasonic signal at the second frequency toward the occupant seating position, receiving a second return echo of the second ultrasonic signal, and determining time duration between emission of the second ultrasonic signal and reception of the second return echo.

4. A method as set forth in claim 2, including controlling the emission of the first ultrasonic signal and the emission of the second ultrasonic signal to cause emission of the second ultrasonic signal subsequent to emission of the first ultrasonic signal and prior to reception of the first signal echo and to cause emission of a subsequent first ultrasonic signal subsequent to emission of the second ultrasonic signal and prior to reception of the second signal echo.

5. A method as set forth in claim 2, wherein said step of determining the occupant location characteristic using at least one of the determined distances is associated with one of the first and second frequencies, said method includes monitoring interference at the other of the first and second frequencies.

6. A method as set forth in claim 2, wherein said step of determining the occupant location characteristic includes determining a distance to an occupant as the occupant location characteristic.

7. An apparatus for determining a vehicle occupant location characteristic, said apparatus comprising:

a sensor having transmitter means and receiver means, said transmitter means for repeatedly transmitting first and second ultrasonic signals, said second ultrasonic signal having a frequency that is different from a frequency of said first ultrasonic signal, said second ultrasonic signal being transmitted at a predetermined time interval after transmission of said first ultrasonic signal, said receiver means for receiving first and second return echoes of the first and second ultrasonic signals, respectively;

means for differentiating said first return echo from said second return echo;

means for determining a time-of-flight of one of said first and second ultrasonic signals; and

means for calculating the vehicle occupant location characteristic using the determined time-of-flight,

said transmitter means for emitting the first ultrasonic signal including a transducer operating at a resonant frequency of said transducer, the resonant frequency being the frequency of the first ultrasonic signal, and said transmitter means for emitting the second ultrasonic signal includes said transducer operating at a first harmonic frequency of said transducer, the first harmonic frequency being the frequency of the second ultrasonic signal.

8. An apparatus for determining a vehicle occupant location characteristic, said apparatus comprising:

a sensor having transmitter means and receiver means, said transmitter means for repeatedly transmitting first and second ultrasonic signals, said second ultrasonic signal having a frequency that is different from a frequency of said first ultrasonic signal, said second ultrasonic signal being transmitted at a predetermined time interval after transmission of said first ultrasonic signal, said receiver means for receiving first and second return echoes of the first and second ultrasonic signals, respectively;

means for differentiating said first return echo from said second return echo;

means for determining a time-of-flight of one of said first and second ultrasonic signals; and

means for calculating the vehicle occupant location characteristic using the determined time-of-flight,

said transmitter means for emitting the first ultrasonic signal including a transducer operating at a first resonant frequency of said transducer, the first resonant frequency being the frequency of the first ultrasonic signal, and said transmitter means for emitting the second ultrasonic signal includes said transducer operating at a second resonant frequency of said transducer, the second resonant frequency being the frequency of the second ultrasonic signal.

9. An apparatus as set forth in claim 8, including means for controlling said transmitter means for emitting the first ultrasonic signal and for emitting the second ultrasonic signal to cause emission of the second ultrasonic signal subsequent to emission of the first ultrasonic signal and prior to reception of the first signal echo and to cause emission of a subsequent first ultrasonic signal subsequent to emission of the second ultrasonic signal and prior to reception of the second signal echo.

10. An apparatus as set forth in claim 8, wherein said means for calculating the vehicle occupant location characteristic includes means for determining a distance to an occupant as the occupant location characteristic.

11. An apparatus for determining a vehicle occupant location characteristic, said apparatus comprising:

a sensor having transmitter means and receiver means, said transmitter means for repeatedly transmitting first and second ultrasonic signals, said second ultrasonic signal having a frequency that is different from a frequency of said first ultrasonic signal, said second ultrasonic signal being transmitted at a predetermined time interval after transmission of said first ultrasonic signal, said receiver means for receiving first and second return echoes of the first and second ultrasonic signals, respectively;

means for differentiating said first return echo from said second return echo;

means for determining a time-of-flight of one of said first and second ultrasonic signals; and

means for calculating the vehicle occupant location characteristic using the determined time-of-flight,

said means for calculating the vehicle occupant location characteristic using the determined time-of-flight being associated with one of the first and second frequencies, said apparatus including means for monitoring interference at the other of the first and second frequencies.

12. A method for determining a vehicle occupant location characteristic, said method comprising the steps of:

echo ranging at a first ultrasonic frequency to determine a first time-of-flight to an occupant seating position;

echo ranging at a second ultrasonic frequency, different from said first ultrasonic frequency, to determine a second time-of-flight to the occupant seating position; and

determining the occupant location characteristic using at least one of the determined times-of-flight,

said step of echo ranging at the first ultrasonic frequency includes emitting a first ultrasonic signal at the first ultrasonic frequency toward the occupant seating position, receiving a first return echo of the first ultrasonic signal, and determining time duration between emission of the first ultrasonic signal and reception of the first return echo, and said step of echo ranging at the second ultrasonic frequency includes emitting a second ultrasonic signal at the second ultrasonic frequency toward the occupant seating position, receiving a second return echo of the second ultrasonic signal, and determining time duration between emission of the second ultrasonic signal and reception of the second return echo,

step of emitting the first ultrasonic signal includes operating a transducer at a first resonant frequency of the transducer, the first resonant frequency being the first frequency, and said step of emitting the second ultrasonic signal includes operating the transducer at a second resonant frequency of the transducer, the second resonant frequency being the second frequency.