An ultrasonic anti-collision detection and warning system adapted to be attached to a corner for warning objects approaching an intersection. The invention comprises first ultrasonic detection means having a first ultrasonic emitter which periodically emits an ultrasonic pulse at a first frequency within a first field of range, and a first ultrasonic sensor which detects an echo of said ultrasonic pulse emitted at said first frequency; second ultrasonic detection means having a second ultrasonic emitter which periodically emits an ultrasonic pulse at a second frequency within a second field of range, and a second ultrasonic sensor which detects an echo of said ultrasonic pulse emitted at said second frequency; a flexible connecting means for connecting said first and second ultrasonic detection around said corner; processor means for determining when an object enters said first field of range based upon the time of an echo received by said first sensor means, said processor means further determining when an object enters said second field of range based upon the time of an echo received by said second sensor means, said processor outputting a signal when objects simultaneously enter said first and second fields of range; and warning means responsive to said signal for outputting a warning signal in said first and second fields of range.

FIELD OF THE INVENTION 
The present invention is directed to devices which activate a warning 
signal when two on-coming vehicles approach a common point from two 
different directions. Specifically, the present invention is directed to a 
device which utilizes ultrasonic sensors to warn two oncoming vehicles 
approaching an intersection from two different directions. 
BACKGROUND OF THE INVENTION 
The present invention is directed to an ultrasonic device which activates 
both visual and audible warning signals when two on-coming vehicles 
approach a common point or intersection from different directions. More 
particularly, the present invention is directed to a novel ultrasonic 
sensing means which is utilized to detect and warn two oncoming vehicles 
or individuals approaching an intersection of an impending collision. 
Each year, millions of dollars in lost man hours and property are caused by 
industrial accidents. Frequently, these accidents are caused when two 
vehicles or individuals approach an intersection at a ninety degree angle. 
Intersecting crosswalks and passageways are common in such workplaces as 
factories, warehouses, and indoor loading docks. Typically, these 
environments are noisy and utilize material transport apparatus. Indoor 
transport apparatus such as forklifts and the like operate by propane or 
electrical power, and are comparatively silent in operation. In addition, 
federal and state occupational safety and health regulations often require 
workers to wear earplugs and other hearing protection devices. 
Accordingly, it is often difficult in industrial environments to hear an 
approaching or oncoming forklift or other indoor vehicle. This is a major 
cause of industrial collisions. 
Previously, large convex mirrors have been utilized at intersections in the 
workplace to provide two-way vision between oncoming vehicles. While such 
mirrors provided a measure of safety, they have several shortcomings. 
First, they are typically mounted at a high location within the respective 
crosswalk and are often difficult to see. More importantly, because these 
mirrors are typically convex, they distort distances and often do not 
identify clearly the respective oncoming objects until both objects are 
too near to prevent a collision. 
Various successful attempts have been made to utilize ultrasonic and 
acoustical sensors to identify objects or obstacles. Most of these prior 
art approaches have been utilized in automotive applications such as U.S. 
Pat. No. 3,681,750 to Larka, and U.S. Pat. No. 4,278,962 to Lin. Others 
have been utilized in avionic applications such as in U.S. Pat. No. 
2,951,248 to Goodell. Finally several patents have been directed toward 
controlling the activation of doors such as U. S. Pat. Nos. 4,029,176 to 
Mills. 
Because of their adaptability to object identification, it would be 
desireable to provide a light, compact, and easily attachable ultrasonic 
based warning device to provide a sound and warning light to prevent 
collisions at intersections in closely confined industrial areas such as 
warehouses, factories and the like. 
It would also be desirable to provide an ultrasonic based signalling 
apparatus which will signal two objects entering a blind intersection at a 
90.degree. angle. 
It would be further desirable to provide a device which can be easily 
placed at a corner and which utilizes ultrasonic signalling to warn 
on-coming objects approaching a corner of an impending collision. 
It is therefore an object of the present invention to provide an ultrasonic 
sensing mechanism which will notify oncoming vehicles approaching at 
90.degree. or other acute or obtuse angles of an impending collision. 
It is a further object of the present invention to provide a collision 
warning device which can be simply attached to a corner. 
It is a further object of the present invention to provide an 
anti-collision device with a flexible pleated connection means which 
permits the device to be folded and detached with respect to any corner. 
It is a further object of the present invention to provide an ultrasonic 
anti-collision sensor which is controlled by a micro processor and which 
emits both flashing light and audible warning signals. 
SUMMARY OF THE INVENTION 
In accordance with the present invention, an ultrasonic anti-collision 
detection and warning system adapted to be attached to a corner for 
warning objects approaching an intersection. The invention comprises first 
ultrasonic detection means having a first ultrasonic emitter which 
periodically emits an ultrasonic pulse at a first frequency in a first 
field of range, and a first ultrasonic sensor which detects an echo of 
said ultrasonic pulse emitted at said first frequency; second ultrasonic 
detection means having a second ultrasonic emitter which periodically 
emits an ultrasonic pulse at a second frequency in a second field of 
range, and a second ultrasonic sensor which detects an echo of said 
ultrasonic pulse emitted at said second frequency; a flexible connecting 
means for connecting said first and second ultrasonic detection around 
said corner; processor means for determining when an object enters said 
first field of range based upon the time of an echo received by said first 
sensor means, said processor means further determining when an object 
enters said second field of range based upon the time of an echo received 
by said second sensor means, said processor outputting a signal when 
objects simultaneously enter said first and second fields of range; and 
warning means responsive to said signal for outputting a warning in said 
first and second fields of range.

DETAILED DESCRIPTION OF THE PRESENT INVENTION 
The present invention is described with reference to the enclosed figures 
wherein the same numbers are used where applicable. 
Referring to FIGS. 1-4, the anti-collision sensor of the present invention 
is described. Referring to FIGS. 1 and 2, the anti-collision sensor 10 of 
the present invention is shown. The invention comprises two ultrasonic 
sensing units 12, 14 separated by a flexible pleated corner. The sensing 
units 12, 14 comprise two rectangular plastic casings which fit around 
respective sides a corner wall 16. The individual sensor units 12, 14 are 
folded with respect to a flexible pleated connector 18 and are attached 
directly to the corner by an adhesive 20, screws or other suitable 
attachment device. 
In the preferred embodiment, the flexible connector 18 comprises a pleated 
plastic connector. The connector permits the flexible attachment of the 
device and also permits internal wires to extend between the units. While 
the present invention is illustrated as being attached to a ninety degree 
corner, it is to be appreciated that the flexible connector enables the 
device to be attached to a corner having any angular configuration. 
Each sensor has a beveled side edge 22, 22a which contains an alarm signal 
light 24, an alarm sound signal 26 and ultrasonic emitter 28 and sensor 
30. The operation of the sensing device will be explained in greater 
detail herein. Referring to FIGS. 1 and 3, the mechanism is activated by a 
switch 32. The unit contains an internal central processing unit 34. The 
central processing unit 34 operates pursuant to a program algorithm which 
controls the device, and which is prestored in a programmable memory 
device 36 such as a ROM or PROM. 
Referring to the block diagram of FIG. 5, the device may be powered by 
either a solar cell or a DC power source 38. As shown in FIG. 4, the 
circuit includes two warning lights as well as two signalling sounders for 
each sensing unit 12, 14. As shown, the circuit also incorporates the two 
sets of ultrasonic emitters and receivers 40, 40a, 42, 42a. 
The present invention is intended to be utilized with a pulse-echo 
ultrasonic system. Ultrasonic sensing systems operate on the principles 
that sound waves reflect or echo, and that the speed of a sound wave 
through air is discretely measurable. Because the speed of sound through 
air is a relative constant (assuming constant factors such as humidity and 
wind speed), the time between an ultrasonic pulse and echo can be 
measured. The time measurement is made by pulsing the transmitter and 
measuring the time interval between the transmitted pulse and the received 
echo. For example, the velocity of sound is approximately 335 meters per 
second. The echo from a target five meters away will arrive in 29 
milliseconds after emission of the transmitted pulse. 
Ultrasonic systems operate in a frequency range of between 20 and 70 KHZ. 
While the present invention may be utilized with a variety of ultrasonic 
transducer, a typical transducer which may be utilized in the present 
invention is a Polaroid Corporation type ultrasonic transducer which 
produces a conical ultrasonic beam at about 50 KHZ that is approximately 
10 degrees wide. The ultrasonic emitters of the present invention should 
have an effective operating range of between 10 and 12 feet. 
The block diagram of FIG. 5 is more particularly shown in the schematic of 
FIG. 6. As shown, the system is powered by DC or solar power supply 38. 
The central processing unit is in series with the pairs of ultrasonic 
emitters and sensors 40, 40a, 42, 42a, and each sensor unit 12, 14 has an 
alarm light and horn. 
In operation, the detection unit is preferably placed at the desired corner 
at a height of between 0 to 12 feet from the ground. The sensor may be 
attached by the adhesive 20 or other attachment device. The device is then 
activated by turning on the switch 32. The device then operates in 
accordance with the prestored algorithm. 
The algorithm for the preferred embodiment is now described with reference 
to the flow chart of FIG. 7. Referring to the algorithm, the power for the 
ultrasonic sensors is activated by power supply 38. Each sensor unit 12, 
14 (designated Q and X) operates at a different frequency so as to prevent 
accidental activation. An initial pulse echo is taken for each sensor and 
prestored in memory as variables Y and K. Next, the respective sensors 
take pulse-echo measurements which are stored as variable U for the Q 
sensor and variable E for the X sensor. Next, U is compared to Y and E is 
compared to K. If both U and E do not equal Y and K, respectively, 
corresponding to the presence of two objects within the field of range of 
the sensors, the microprocessor activates the warning lights and horn. 
After a preset interval, the system resets. If no objects or only one 
object is within the field of range of either of the sensors the program 
loops and continues to sample. Thus, the present device continually 
samples two fields of range. As shown in FIG. 8, when two objects 
simultaneously enter the first and second fields of range, the respective 
warning signals are activated. 
While the present invention has been described with reference to a 
preferred embodiment, it is to appreciated by those skilled in the art 
that other embodiments fall within the spirit and scope of the present 
invention and that the true scope of the present invention is to be 
determined with reference to the claims appended hereto.