Ultrasonic obstacle sensor
First Claim
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1. An ultrasonic obstacle sensor for an automotive vehicle comprising:
- an ultrasonic transmitter for generating ultrasonic waves;
an ultrasonic receiver for receiving ultrasonic waves and generating a corresponding signal;
an amplifier for amplifying the signal from the ultrasonic receiver by an amplification factor and generating an amplified signal;
an averager for generating an average signal indicating the average of the amplified signal;
a reference signal generator for generating a reference signal;
a comparator for comparing the reference signal with the amplified signal and generating an obstacle detection signal indicating when the amplified signal exceeds the reference signal; and
control means for varying at least one of the magnitude of the reference signal and the amplification factor of the amplifier in accordance with variations in the average signal.
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Abstract
Ultrasonic waves are transmitted from an ultrasonic transmitter mounted on a vehicle towards a road surface. An ultrasonic receiver mounted on the vehicle receives ultrasonic waves reflected from the road surface and generates a signal which is amplified by an amplifier. The amplified signal is compared with a reference signal to detect components in the amplified signal due to obstacles on the road surface. The magnitude of the reference signal and/or the amplification factor of the amplifier is controlled to maintain a constant ratio between the average of the reference signal and the average of the amplified signal.
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Citations
12 Claims
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1. An ultrasonic obstacle sensor for an automotive vehicle comprising:
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an ultrasonic transmitter for generating ultrasonic waves; an ultrasonic receiver for receiving ultrasonic waves and generating a corresponding signal; an amplifier for amplifying the signal from the ultrasonic receiver by an amplification factor and generating an amplified signal; an averager for generating an average signal indicating the average of the amplified signal; a reference signal generator for generating a reference signal; a comparator for comparing the reference signal with the amplified signal and generating an obstacle detection signal indicating when the amplified signal exceeds the reference signal; and control means for varying at least one of the magnitude of the reference signal and the amplification factor of the amplifier in accordance with variations in the average signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. An ultrasonic obstacle sensor for an automotive vehicle comprising:
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an ultrasonic transmitter for intermittently generating ultrasonic waves, the ultrasonic transmitter being mounted on the vehicle so as to transmit the ultrasonic waves diagonally forward of the vehicle towards a surface on which the vehicle is disposed; an ultrasonic receiver for receiving ultrasonic waves reflected from the surface and generating a corresponding signal; an adjustable amplifier for amplifying the signal from the ultrasonic receiver and generating an amplified signal; an averager for generating an average signal indicating the average of the amplified signal; a reference signal generator for generating a reference signal; a comparator for comparing the reference signal with the amplified signal and generating an obstacle detection signal indicating when the amplified signal exceeds the reference signal; and an amplification factor controller responsive to the average signal for controlling the amplification factor of the amplifier so that the average signal has a constant, prescribed value.
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11. An ultrasonic obstacle sensor for an automotive vehicle comprising:
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an ultrasonic transmitter for intermittently generating ultrasonic waves, the ultrasonic transmitter being mounted on the vehicle so as to transmit the ultrasonic waves diagonally forward of the vehicle towards a surface on which the vehicle is disposed; an ultrasonic receiver for receiving ultrasonic waves reflected from the surface and generating a corresponding signal; an amplifier for amplifying the signal from the ultrasonic receiver and generating an amplified signal; an averager for generating an average signal indicating the average of the amplified signal; a reference signal generator for generating a reference signal; a comparator for comparing the reference signal with the amplified signal and generating an obstacle detection signal indicating when the amplified signal exceeds the reference signal; and means for controlling the reference signal generator so that the ratio of the average of the reference signal to the average signal is constant.
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12. A method of detecting obstacles on a road surface in front of an automotive vehicle comprising the steps of:
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intermittently generating ultrasonic waves diagonally forwards of the vehicle towards the road surface; receiving ultrasonic waves reflected from the road surface and generating a corresponding received signal; amplifying the received signal by an amplification factor to obtain an amplified signal; averaging the amplified signal to obtain an average signal; generating a reference signal for comparison with the amplified signal; comparing the reference signal with the amplified signal and generating an obstacle detection signal indicating when the amplified signal exceeds the reference signal; and controlling at least one of the reference signal generator and the amplification factor so that the ratio of the average signal to the average of the reference signal is constant.
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Specification