US 4,561,064 AGranted

Non-contacting distance measuring system

OwnerGerhard Bruggen, Dieter Karr +1inventors

InventorsGerhard Bruggen, Dieter Karr, Wolfgang Rottler

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Abstract

To determine if a pulsed beam system, typically an ultrasonic pulsed beam system, which is located externally of a motor vehicle is in operative condition, a transmitter (14) projects a beam to a fixed reflector (16) located on the vehicle, and one (19) of a group of timing stages (18; 19, 20, 21) evaluates the transit time to the reflector. If the transit time to the reflector is slightly less than a predetermined time interval (Tc), so that the threshold timing level (Tc) is passed, a first indication, for example a frequency at a first tone (f1), generated by an acoustic tone generator (30) is reproduced in a loudspeaker; if, then, an obstruction is sensed by the beam, and the distance between the transmitter (14) and the obstruction (17) which forms a reflecting object drops below a first predetermined distance represented by a time period (T2), a second one of the transit time stages responds, and, through logic gates (22-24, 28, 29) provides a second discrete output frequency (f2) in the loudspeaker. If the vehicle closely approaches the reflecting object or obstruction (17), a third frequency (f3) is reproduced by the loudspeaker (26) and, additionally, a warning signal can be given. The system can be connected to the reverse gear or rear light switch, so that, if no obstruction is sensed, and only the signal from the reflector is reproduced, an audible indication of "reverse gear engaged" is provided, thus simultaneously providing a reverse gear signal as well as a signal representative of proper operation of the system. To compensate for ambient condition, dirt on the transmitters, and the like, the timing intervals by the transit time stages responding to the obstruction can be changed (FIG. 2) by providing a calibrating input based on actual transit time from the transmitter (14) to the fixed reflector (16).

Claims15

Dependent claims

In combination with a vehicle (V), a non-contacting distance measuring system for determining the distance between a transmitting object and a reflecting object (17) having an ultrasonic pulse train beam transmitter (14) for projecting an ultrasonic pulsed beam train from the rear portion of the vehicle (V) to an obstruction forming said reflectig object (17);

means (15, 13) for receiving reflected signals from said reflecting object, including a beam receiver (15),
said beam transmitter (14) and receiver (15) being located externally of the body of the vehicle (V);
transit time determination means (18) coupled to the pulse projecting means in said beam transmitter, and including means for determining the time of transit of the pulses of the beam from said transmitter to said reflecting object to determine said distance when the transit time, per unit distance, is known;
indicator means (26, 27) for providing different and discrete output indications, said indicator means furnishing an output indication when said distance drops below a pretermined value;
a reflector (16) located on the vehicle and spaced at a prdetermined distance from said beam transmitter (14) in a portion of the beam in the path thereof;
said transit time determination means (18) comprising a plurality of transit time stages (19, 20, 21) responding, in steps, to different transit time periods of the beam from said transmitter (14) to, respectively, said reflector (16) and the obstruction forming said reflecting object (17), and return to said receiver,
one of said stepped transit time stages (19) being associated with the transit time of signals from said transmitter (14) to said reflector (16) and received in said receiver (15);
and function testing logic means (22, 23, 24, 25, 29, 30) connected to and controlled by said stepped transit time stages and responsive to the portion of the transmitted beam which is reflected by said reflector (16) and further responsive to the beam reflected from said obstruction forming said reflecting object (17) and received in said receiver (15), said function testing logic means being connected to control the discrete output provided by the indicator means to provide a first characteristic of a functionality test of the system upon energization of the system and reception of reflected signals from said reflector (16), and providing an output of a discretely different characteristic by said indicator means upon reception of signals from said obstruction forming said reflecting object (17), and disabling indication of said first characteristic by said indicator means.

5 more elements

In a vehicle,

a method of providing a non-contacting collision avoidance distance measurement including the steps of
radiating a pulsed ultrasonic measuring beam in form of a pulse train from an ultrasonic transmitter (14) located at a rear portion of the vehicle (V) towards the rear thereof;
receiving the pulsed measuring beam in a receiver (15) when reflected from an obstruction forming a reflecting object (17),
said beam transmitter and beam receiver being located externally of the body of said vehicle;
determining the distance from the transmitter to the object (17) based on measurement of the transit time of the beam between said transmitter and said receiver;
and testing the operability of the system comprising
providing a test reflector (16) located on said vehicle, and positioned by a predetermined distance with respect to said transmitter, and reflecting a portion of the beam to the receiver;
measuring, based on discrete transit time intervals, the transit time of the beam from the transmitter to said test reflector (16) and reflected to said receiver (15);
providing an output indication of a first discrete characteristic (f1) upon reception of signals from the reflector (16) within a first time interval associated with said predetermined distance;
timing reception of signals received from said object (17);
and
inhibiting generation of output signals of said first discrete characteristic and generating output signals of a second discrete characteristic (f2) if the time interval of the travel of the beam between said transmitter (14), said object, and said receiver drops below a given value.

9 more elements

Dependencies are inferred from the claim text.