Note: Descriptions are shown in the official language in which they were submitted.
Vehicle SafetY Device
Field of the Invention
The invention relates to accident prevention systems for vehicles
and in particular to safety devices for the prevention of collisions
between vehicles and pedestrians.
B~ckv.round of the I~vention
A large number of pedestrians are Xilled every year in collisions
with vehicles. Such accidents are especially tragic when the person
in~ured or killed is a child who only moments earlier stepped off the
accident vehicle, e.g. a school bus. Although school buses are equipped
with large parabolic mirrors which assist the driver in monitoring the
environment of the school bus, some regions close to the bus and all the
area under the bus cannot be seen by the driver. Furthermore, even a
momentary lapse of observation by the driver can result in fatal in~ury.
In fact, a distressingly large number of school bus accidents are caused
by driver error. In an effort to overcome these problems, school buses
have been equipped with mechanical arms, which are extendible from the
front end of the bus to force those children which pass in front of the
bus to walk where the driver can actually see them without the aid of
mirrors. However, mechanical problems associated with these arms, such
;~ as sei~ing in the extended or retracted condition, especially in winter,
have prevented their wide-spread introduction. Furthermore, the driver
must still maintain constant vigilance during entry and exit of
passengers and accidents due to driver error cannot be prevented.
Parent organizations and the general public are therefore pressuring
the transport ministries and school boards to equip school buses with an
effective safety ~ystem which sub~tantially reduces, if not eliminates,
these types of accidents and operates without driver intervention.
~ utomatic surveillance and accident prevention systems are known
from Canadian Patent 1,237,798 by Dombrowski and U.S. Patent 4,779,095 by
Guerreri. Dombrowski discloses a driver alerting device for the -
detection of an ob~ect beneath, forwardly of and to the passenger
discharging side of a school bus. The device operates on the doppler
shift principle and includes micro-wave radar transceivers and an
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electronic circuit which activates an audible alarm when a doppler shift
i9 detected between the transmitted signals and any reflected signals.
Although the ~ystem may be used to detect ob~ects which are moving
relative to the bus, relatively stationary ob~ects or persons cannot be
detected, since stationary ob~ects do not cause a doppler 9hift. Thus, a
child which fell in front of the bus and lies unconscious out of view of
the driver could not be detected, which could result in serious in~ury to
tho child. Also, moving ob~ects which are close to but not in a
dangerous area around the bus may triBger false alarms, which could lead
to the driver ignoring the alarm when no child is visible in the close
vlclnity of the bus. Finally, the microwave radar transmitters, antennas
and analysis circuitry required make the system an expensive and, thus,
uneconomical solution.
Guerreri (U.S. Patent 4,779,095) describes an image change detection
Aystem for the automatic monitoring of a region beneath and around a
school bus. The system compares a stored base line ima8e of the
environment to one or more subsequent images to detect differenc~s
therebetween. The images are divided into a number of pixels and
deviations between images are detected by matching the pixels of a
subsequent image with the pixels of the first image. If a preselected
pixel deviation thre~hold is exceeded, an audible or vi~ible alarm is
sounded or the vehicle is disabled by the system. Each pixel corresponds
to one photodiode of a monolithic photodiode array. Although this system
should be able to detect an unconscious child, it will also detect other
moving or stationary ob~ects which appear in the survellled region after
the base line image was stored, such as leaves, rocks, pieces of paper
etc. Thus, this system requires read~ustment of the deviation threshold
to different environmental parameters, in order to avoid false alarms.
In addition, the system includes Qophis~icated electronic circuits and
components which results in high manufacturing cost and makes this system
uneconomical.
Thusj a safety system for vehicles is desired which is of a simple
construction, is economically manufactured, and reliably detects the
presence of a moving or stationary person in the vicinity of the vehicle.
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Swmmarv Of The Invention
It is an ob~ect of the invention to provide an automatic vehicle
safety device for the detection of a person in a selected surveillance
~rea close to or under the vehicle, which device i9 of simple
construction and may be manufactured and installed at relatively low cost.
~ t is another ob~ect of the invention to provide a vehicle safety
d~vlce which will detect both a moving and a stationary person in the
surveillance area.
It is a further ob~ect of the invention to provide a vehicle safety
device, which is of simple construction and will automatically disable
the vehicle without intervention by the driver when a person is detected
in the surveillance area.
Accordingly, the invention now provides a vehicle safety device
including an infrared (IR) motion sensing means for detecting the
presence of a per~on in a selected surveillance zone ad~acent the
veh~cle, the sensing means producing an output signal upon detection of a
person, and a stopping means connected to the sensing means for
;~ automatically disabling the vehicle upon receipt of the output signal.
The IR motion sensing means preferably includes an IR motion sensor
fastened to a mounting surface of the vehicle and means for swaying the
motion sensor relatlve to the mounting surface to such an extent that a
motionless person located in the surveillance area is detectable by the
; motion sensor.
The vehicle safety device preferably further includes a control
; 25 means for maintainin8 the safety device act~vated for a selected time
interval after closing the vehicle door. The safety device may be
activated by way of a door switch and may further include a door locking
mean~ for maintaining the ~ehicle door open to prevent deactivation of
` the safety device while a person i9 detected. The sensing means
j~ 30 preferably includes a plurality of IR motion sensors positioned about the
vehicle 90 that the combined surveillance area~ of the sensors completely
cover the selected surveillance zone around and under the vehicle.
In a preferred embodiment, the sensing means is an IR motion
detector positioned at a central location in the vehicle and the system
further includes fiber optic means for transmitting IR radiation emitted
within the surveillance zone to the IR motion sensor. The stopping means
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is preferably a brake actuating means for relea~ably applying a bra~e of
the vehicle.
DescriDtion Of The Preferred Embodiment
Preferred embodiments of the invention will now be further described
by way of example only and with reference to the following drawings,
whcrein
Figure 1 ls a schematic diagram of a preferred embodiment of a
vehicle saety system in accordance with the invention;
Figure 2 is a schematic diagram of another embodiment of a vehicle
safety system in accordance with the invention;
Figure 3 illustrates the brake actuating arrangement used in the
embodiments shown ln Figures 1 and 2;
Figure 4 indicates the preferred locations of the IR motion sensors,
when the vehicle safety device is installed in a school bus;
Figure 5 shows the swaying arrangement for the sensors; and
Flgure 6 schematically illustrates a portion of another embodiment
having one central IR motion sensor and several radiation transmitting
fiber optic cables.
The preferred embodiment of a vehicle safety system in accordance
with the invention illustrated in Figure 1, is preferably installed in a
school bus in a manner described further below and includes a number of
IR motion sensors 10 (only one shown for reasons of clarity) for the
detection of a person within the range of the sensor(s), and a stopping
arrangement 20 for the disabling of the vehicle when a person-30 is
detected by the sensor.
IR motion sensors generally go through a ~elf-testing program after
they are switched on. This program can run from 20 to 60 seconds during
whlch time the sensors cannot be used for their intended purpose.
Therefore, in this embodiment, each sensor 10 is continuously supplied
with operating voltage either directly from the vehicle battery or from
the ignition switch of the vehicle. The remainder of the device is
activated by a door switch 40 which in the open position of the door
supplies positive operating voltage to one of the normally open contacts
64 of a control relay 60 through a conductor 140. The other of contacts
64 is connected to the stopping arrangement 20 through a conductor 142.
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The stopping arrangement 20 includes a pneumatlc brake pedal operating
cylinder 22, the operation of which will be discussed in detail further
below with reference to Figure 3, a pressurized air storage tank 24 and a
~olenoid 26. Solenoid 26 controls the supply of pressurized air from
~torage tank a4 to the brake pedal operating cylinder 22 and a plunger
coil 27 of the ~olenoid is connected to conductor 142. Sen~or 10
inc~udo~ a pyroelectric detector 12 and a signal processing unit 14 which
produces an output ~ignal when the overall IR radiation emitted within
the range of the sensor has changed. The sensors used in this embodiment
are Paradox Avantage (Pirotech, Quebec, Canada) or SafeHouse ~InterTan,
Canada), but other commercially available infrared motion detectors may
be used as well. A conductor 144 connects the output of the sensor 10
with a driver alerting display 50, which is mounted within view of the
driver, for example in the dashboard of the school bus. Display 50
includes a schematic diagram 52 of the bus and has a light emitting diode
~LED) 54 for each sensor 10 mounted to the bus, which LEDs are
respectively connected to the conductors 144 of the indivldual sensors.
- A conductor 146 connects a ~unction 147 on conductor 144 with a switching
coil 62 of the relay 60. The safety system further includes a door
locking arrangement 42 which will lock the bus door in the opened
position when a person is detected in the surveillance area around the
bus 90 that the driver cannot disable the system and drive away while it
is not safe to do 90. This will substantially avoid accidents caused by
driver error and provides added safety for discharged passengers still
close to the bus. Any arrangement may be used which is operably linked
- to the sensor 10, the relay 60 or the stopping arrangement 20 to lock the
bus door in the opened position when a person i3 detected. However, in
this embodiment, the door locking arrangement i9 a pneumatic cylinder 44
which is supplied with pressurized air from the tank 24 through a tubing
30 126. The air supply to cylinder 44 is also controlled by solenoid 26.
The pneumatic cylinder 44 is affixed overhead to the door frame 46 and
the door 48 respectively, but may also be connected to the door opening ~;
mechanism operated by the driver (not shown).
In operation, the driver opens the vehicle door (not shown) after
~5 having stopped the vehicle, wh~reby door switch 40 is closed. When now a
person walkQ through the range of sensor 10, signal processing unit 14
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produces an output signal which is transmitted through conductor 144 to
the associate LED 42 of display 50. Thus, the location of the person
detected relative to the bus will be apparent from the display.
Furthermore, the output signal is transmitted through conductor 146 to
~witching coil 62 which flips relay 60 thereby closing contscts 64 90
thAt operating power i9 supplied to the plunger coil 27 of solenoid 26.
The ~lunger coil 27 produces a magnetic force which moves the plunger
~not shown) of the solenoid 26 to a position where the brake pedal
operating cylinder 22 is supplied with pressurized air from tank 24
through tubing 120 and 122. A brake pedal 70 of the bus is depressed by
the retraction of cylinder 22, which locks the brakes of the bus (not
shown). Stopping arrangement 20 is activated and the brakes of the bus
remain applied as long as a person is detected by one of the sensors 10.
Pressurized air from tank 24 i9 supplied simultaneously to the brake
- 15 pedal operating cylinder 22 and to the door locking cylinder 44.
- Cylinder 44 extends and locks the door in the opened position, 90 that
the safety device cannot be deactivated by the driver as long as a person
; i9 detected by ane of the sensors. Thus, the bus i9 reliably disabledand bus/passenger collisions are substantially prevented when the safety
system i9 activated and a person i9 within the range of any one of the
sensors 10. The stopping arrangement 20 may also include a pneumatic
accelerator pedal locking cylinder 28 which is supplied with pressurized
air from tank 24 through tubing 122. Thus, when the stopping arran8ement
20 i9 activated, cylinder 28 is extended and locks the accelerator pedal
in the idle position.
The safety system illustrated schematically in Figure 2 includes the
same basic components as the system discussed above, namely at least one
IR motion sensor 10, a stopping arrangement 20, a door switch 40, a door
locking arrangement 42 and a driver alerting display 50. The
construction and function of these components i9 as di~cussed above in
relation to Figure 1. The system further includes a timed switch 80,
which keeps the system activated for a selected time internal (10-15s)
- after the bus door has been closed. The control input of timed switch 80
is connected through conductor 140 to the door switch 40. The power
input and output of the timed switch 80 are respectively connected to the
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positive power source (battery or ignition switch) of the bus and through
a conductor 150 to one of ~he contacts 64 of relay 60.
During operation, the opening of the bus door closes door switch 40,
whlch provides operating voltage to timed switch 80. The timed switch 80
closes and in turn connects the contact 64 with the vehicle power
~u~ply. When a person is detected by sensors 10, an output ~ignal is
produced and transmitted through conductors 144, 146 to the switching
coil 62 of relay 60, which flips relay 60 to the activated condition
wh~rein positive voltage is supplied thr~ugh the conductor 142 to the
stopping arrangement 20 as in the embodiment shown in Figure 1. Thus,
the brakes are applied and the door is locked in the opened po~tion
while a person is detected by sensor 10. When no persons are detected by
the sensor 10 and the driver closes the door 48, the timed switch 80
provides power to one of the contacts 64 for a preselected time interval
(10-15 seconds) so that the bus will be automatically stopped should a
child come running back to the bus which has led to serious accidents in
the past when a child forgot something in the bus and ran back to get
it. This substantially reduces the risk of a child having left the range
of the sensors being hit when running back to the bus.
Turning now to Figure 3, a brake pedal 162 is pivotally connected at
a first pivot 163 to a main brake cylinder operating rod 164. Main brake
cylinder 165 is affixed to a fire wall 166 of the vehicle. Pneumatic
brake pedal operating cylinder 22 is also affixed to the firewall 166 and
is connected to a second pivot 167 on the brake pedal 162 by a cylinder
rod 168, which includes a pivot receiving elongated eyelet 169. Thus,
the brake pedal 162 can be depressed by the driver of the vehicle when
the cylinder 22 is in the extended position whereby the second pivot 167
slides longitudinally in the eyelet 169. On the other hand, w~en
cylinder 22 is supplied with pressurized air from tank 24, (see ~ig. ~ or
2) through air supply tube 122, the cylinder rod 168 is retracted which
results in the brake pedal being depressed and the brakes being applied.
When cylinder 22 is no longer supplied with pressurized air, a resetting
spring (not shown) mounted on the braXe pedal p~vot 171 returns the brake
pedal 162 to the undepressed posi~ion whereby the cylinder rod 168 of
` 35 cylinder 22 is again in the extended position.
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Figure 4 shows the preferred location~ of the sensors 10 on a school
bus 100. The sensors are positioned so that their ranges overlap and
that their combined ranges form a continuous surveillance zone around and
under the bus.
Fl~ure 5 lllu~trates the swaying arrangement used to moderately sway
th~ ~ensor~ 10 5 to 15 around a pivot 170 mounted to the school bus 100
~sce Figure 4). The actual degree of swaying required for the sensor 10
to de~ect ~n unconscious person depends on the model of IR sensor used,
but can be readily selected by the art skilled person. Each sensor 10 i8
individually mounted on a base plate 173 which includes a mount 174
having a bore 176 for receiving the pivot 170. An automatically
reciprocating pneumatic cylinder 178 is attached to an edge of the base
plate 172 by a ball and socket arrangement 180 whereby the ball 182 is
affixed to a cylinder shaft 184 and the socket 186 is affixed to the base
plate 172. Cylinder 178 iq supplied with pressurized air from the tank
24 ~see Figures 1 and 2) through air supply lines 188 and 189.
Turning now to Figure 6, a safety device in accordance with the
invention may include only one sensor 10 which is installed in the
vehicle at a central location. Infrared radiation from within a selected
- 20 surveillance area around and under the vehicle is transmitted to thesensor 10 by fiber optic cables 192. In this embodiments, a first lens
lg4 ls positioncd at each of the locations on the vehicle where a sensor
10 would be installed if the embodiments of Figure 1 or 2 were used. The
first lens 194 focuses the IR radiation emitted within the surveillance
area corresponding to the range of a sensor 10 installed at the same
location onto an end of one of the fiber optic cables. A second lens 196
is placed in front of the sensor 10, which lens focuses all radiation
transmitted by all cables 192 onto the pyroelectric detector 12 of the
sensor. Thus, all IR radiation emitted in the combined surveillance
areas of all lenses 194 is transmitted to the sentral sensor.
Alternatively, two sensors (not shown) may be used which by way of a
mirror arrangement are both supplied with radiation from the surveillance
zone so that the device wilI still function should one of the sensors
fail. Each lens 194 may be mounted on a base plate 172 of a swaying
arrangement as shown in Figure 5 to permit detection of a stationary
person located in the surveillance area around the bus.
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In the embodiments shown in Figure 1 and 2, the door switch 40 may
also be used to ~upply operating power directly to the plunger coil 27 of
solenoid 26 while the door is open. This wlll prevent creeping of the
bus whlle the door is open, which has also led to accidents in the past.
Although the construction and mounting oP the braXe pedal operating
cylinder 22 shown in Figure 3 is preferred) the cylinder 22 may extend
when ~u~plied with pressuriæed air and may be mounted not to the firewall
but connected, for example, to the steering column of the vehicle or any
other easily acce~sible structural element of the vehicle close to the
braXe pedal.
It will be readily apparent that the stopping arrangement 20 may
also function hydraulically when the operating fluid i8 a liquid.
Furthermore, the pressurized operating fluld may be obtained from a
hydraulic or pneumatic system already installed in the vehicle. In the
alternative, the tanX 24 may be filled with pressuri~ed fluid by way of
an appropriate compressor or pump driven by the vehicle's engine or
operated independently therefrom.
Changes and modifications in the specifically described embodiments
can be carried out without departing from the scope of the invention
which is intended to be limited only by the scope of the appended claims.
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