Ultrasonic obstacle sensor

Claim 2

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.

Claim 3

An obstacle sensor as claimed in claim 1, wherein the control means comprises means for varying at least one of the magnitude of the reference signal and the amplification factor of the amplifier so that the ratio of the average signal to the average of the reference signal is constant.

Claim 4

An obstacle sensor as claimed in claim 1, wherein: the control means comprises an amplification factor controller responsive to the average signal for controlling the amplification factor of the amplifier so as to maintain the average signal equal to a prescribed value.

Claim 5

An obstacle sensor as claimed in claim 1, wherein: the control means comprises means responsive to the average signal for controlling the reference signal generator so that the average of the reference signal is a constant multiple of the average signal.

Claim 6

An obstacle sensor as claimed in claim 1, wherein the vehicle is disposed on a surface, and the ultrasonic transmitter is mounted on the vehicle so as to transmit ultrasonic waves diagonally forwards of the vehicle towards the surface.

Claim 7

An obstacle sensor as claimed in claim 1, wherein the ultrasonic transmitter comprises means for generating ultrasonic waves intermittently.

Claim 8

An obstacle sensor as claimed in claim 1, further comprising a voltage clipper connected between the amplifier and the averager for clipping the amplified signal to a prescribed voltage and providing the clipped signal to the averager.

Claim 9

An obstacle sensor as claimed in claim 1, wherein the reference signal has a triangular wave form.

Claim 10

An obstacle sensor as claimed in claim 1, wherein the reference signal generator comprises means for generating a plurality of reference signals having different magnitudes, and the comparator comprises means for comparing the amplified signal with each of the reference signals and generating an obstacle detection signal indicating the result of each comparison.

Claim 11

An ultrasonic obstacle sensor for an automotive vehicle comprising: 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.

Claim 12

An ultrasonic obstacle sensor for an automotive vehicle comprising: 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.

Claim 13

An ultrasonic obstacle sensor for an automotive vehicle comprising: 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.

Claim 14

An ultrasonic obstacle sensor for an automotive vehicle comprising: 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.