Method and System for Detecting an Occupant Using Reflected Signals
First Claim
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1. A method for detecting an occupant in a vehicle comprising the steps of:
- emitting a first emitted signal having a first wavelength;
detecting a first reflected signal based on the first emitted signal, wherein the first reflected signal has a first phase difference with respect to the first emitted signal;
determining a first motion signal based on the first phase difference, said first motion signal having a first motion signal magnitude;
if the first motion signal magnitude is greater than a first threshold, determining the presence of an occupant based on the first motion signal;
if the first motion signal magnitude is less than the first threshold, emitting a second emitted signal having a second wavelength,detecting a second reflected signal based on the second emitted signal, wherein the second reflected signal has a second phase difference with respect to the second emitted signal;
determining a second motion signal based on the second phase difference, said second motion signal having a second motion signal magnitude; and
if the second motion signal magnitude is greater than a second threshold, determining the presence of an occupant based on the second motion signal.
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Abstract
An occupant detection system emits an ultrasonic signal for detecting the presence of an occupant by reflecting the signal off the occupant and then determines that an occupant is present by detecting motion of the occupant. One type of motion that is detected is the small rhythmic motion associated with respiration. The motion detection system improves detection of motion smaller than a wavelength of the ultrasonic signal by shifting the wavelength of the ultrasonic signal to increase the detected motion signal. The system may also determine the presence of an occupant by comparing the motion signal to a motion pattern that corresponds to respiration.
15 Citations
21 Claims
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1. A method for detecting an occupant in a vehicle comprising the steps of:
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emitting a first emitted signal having a first wavelength; detecting a first reflected signal based on the first emitted signal, wherein the first reflected signal has a first phase difference with respect to the first emitted signal; determining a first motion signal based on the first phase difference, said first motion signal having a first motion signal magnitude; if the first motion signal magnitude is greater than a first threshold, determining the presence of an occupant based on the first motion signal; if the first motion signal magnitude is less than the first threshold, emitting a second emitted signal having a second wavelength, detecting a second reflected signal based on the second emitted signal, wherein the second reflected signal has a second phase difference with respect to the second emitted signal; determining a second motion signal based on the second phase difference, said second motion signal having a second motion signal magnitude; and if the second motion signal magnitude is greater than a second threshold, determining the presence of an occupant based on the second motion signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 21)
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11. A method for detecting an occupant in a vehicle comprising the steps of:
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emitting a first emitted signal having a first wavelength; detecting a first reflected signal that is a reflection of the first emitted signal; determining a first modulated signal based on a phase difference of the first reflected signal relative to the first emitted signal; determining a first motion signal by amplitude demodulating the first modulated signal, said first motion signal having a first motion signal magnitude; if the first motion signal magnitude is greater than or equal to a first threshold, determining the presence of an occupant based on the first motion signal; if the first motion signal magnitude is less than the first threshold, selecting a second wavelength distinct from the first wavelength; emitting a second emitted signal having the second wavelength; detecting a second reflected signal that is a reflection of the second emitted signal; determining a second modulated signal based on a second phase difference of the second reflected signal relative to the second emitted signal; determining a second motion signal by amplitude demodulating the second modulated signal, said second motion signal having a second motion signal magnitude; and if either the first motion signal magnitude or the second motion signal magnitude is greater than a second threshold, determining the presence of an occupant based on the first motion signal and the second motion signal, wherein the step of selecting the second wavelength is effective to produce a second nominal phase difference based on the second modulated signal that differs about 40 to about 140 degrees or about −
40 to about −
140 degrees from a first nominal phase difference based on the first modulated signal.
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12. A system for detecting an occupant in a vehicle comprising:
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an emitter for emitting a signal; a detector for detecting a reflected signal; and a controller configured to output a first excitation to the emitter for emitting a first emitted signal having a first wavelength, receive a first detection signal from the detector for detecting a first reflected signal based on the first emitted signal, wherein the first reflected signal has a first phase difference with respect to the first emitted signal, determine a first motion signal based on the first phase difference, wherein said first motion signal has a first motion signal magnitude, wherein if the first motion signal magnitude is greater than a first threshold, determining the presence of an occupant, if the first motion signal magnitude is less than the first threshold, emitting a second emitted signal having a second wavelength, detecting a second reflected signal based on the second emitted signal, wherein the second reflected signal has a second phase difference with respect to the second emitted signal, determining a second motion signal based on the second phase difference, said second motion signal having a second motion signal magnitude, and if the second motion signal magnitude is greater than a second threshold, determining the presence of an occupant, wherein the second emitted signal is effective to produce a phase difference shift in the second phase difference relative to the first phase difference of about 40 to about 140 degrees or about −
40 to about −
140 degrees. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19)
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20. A method for detecting an occupant in a vehicle having a transducer and a controller, said method comprising the steps of:
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outputting a first excitation having a first frequency by the controller to the transducer to emit a first emitted signal; receiving a first detection signal by the controller from the transducer to detect a first reflected signal based on the first emitted signal, wherein the first detection signal has a first phase difference with respect to the first excitation signal; determining a first motion signal based on the first phase difference, said first motion signal having a first motion signal magnitude; if the first motion signal magnitude is greater than a first threshold, determining the presence of an occupant based on the first motion signal; if the first motion signal magnitude is less than the first threshold, outputting a second excitation signal to the transducer to emit a second emitted signal having a second frequency, receiving a second detection signal from the transducer to detect a second reflected signal based on the second emitted signal, wherein the second reflected signal has a second phase difference with respect to the second emitted signal; determining a second motion signal based on the second phase difference, said second motion signal having a second motion signal magnitude; and if the second motion signal magnitude is greater than a second threshold, determining the presence of an occupant based on the second motion signal.
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Specification