Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
CA 02559386 2006-09-27
DOOR CONTROL APPARATUS
This application is a divisional of Canadian patent application Serial
No. 2,236,736 filed internationally on November 4, 1996 and entered nationally
on
May 4, 1998.
The present invention relates to safety appara-
tus which finds application, for example, in automatic
door apparatus and machine tools.
Automatic doors are in widespread use in var-
ious applications, such as elevators, buses and trains.
Considerations of personal safety require that doors not
be closed when there is a danger that a person might be
impacted thereby. While not compromising safety consider-
ations, considerations of efficiency dictate that doors
be closed as promptly and quickly as possible.
There exist various techniques and apparatus
for sensing the absence of a person and his accouter-
ments within a predefined zone and consequently operating
an automatic door. U.S. Patents 4,029,176; 4,590,410;
4,779,240; 4,976,337; 5,001,557; 5,149,921; 5,276,391;
5,412,297; 5,420,430; RE 33,668 and RE 30,719 exemplify
the state of the art. U.S. Patent 5,412,297 employs a
tactile obstruction detector, while U.S. Patents
4,590,410 and 5,276,391 employ optical detectors. U.S.
Patent 2,826,753, which relates to object detection in a
confined environment and not to door opening or closing,
and U.S. Patents RE 30,719; 4.029,176 and 5,147,410
employ acoustic energy and are believed by applicant to
be the closest prior art to the present invention. Other
distance and direction measuring apparatus is described
in U.S. Patents 5,467,072; 5,450,057; 5,373,482;
5,341,344; 5,339,075; 5,337.289 and 5,319.611.
The present invention seeks to provide a secure
and efficient door operating system which maximizes door
closing efficiency while minimizing the risk of injury to
users.
There is thus provided in accordance with a
preferred embodiment of the present invention a door
control apparatus for vehicles including at least one
CA 02559386 2006-09-27
2
sensor viewing at least one region in the vicinity of a
door, logic circuitry responsive to the at least one
sensor for providing at least one region clear output
signal, automatic door opening and door closing apparatus
responsive at least to the absence of a region clear
output signal to cause opening of the door and responsive
at least to the presence of a region clear output signal
to cause closing of the door.
Furthermore in accordance with a preferred
embodiment of the present invention wherein the automatic
door opening and door closing apparatus is responsive at
least to the absence of a region clear output signal to
cause opening of the door and responsive at least to the
presence of the same region clear output signal to cause
closing of the door.
Additionally in accordance with a preferred
embodiment of the present invention wherein the automatic
door opening and door closing apparatus is responsive at
least to the absence of a first region clear output
signal in respect of a first region to cause opening of
the door and responsive at least to the presence of a
second region clear output signal, different from the
first region clear output signal, in respect of a second
region different from the first region, to cause closing
of the door.
Furthermore in accordance with a preferred
embodiment of the present invention, the first and second
regions are mutually overlapping, mutually exclusive and
partially mutually overlapping.
There is also provided in accordance with a
preferred embodiment of the present invention a safety
apparatus for preventing injurious engagement of machin-
ery with a user and clothing and accouterments thereof
within a predetermined volume including a sensor having
two modes of operation, a reference sensing mode of
operation for sensing the boundaries of the predetermined
CA 02559386 2006-09-27
3
volume, and an engagement prevention mode of operation
for sensing the presence of a user and clothing and
accouterments thereof within the predetermined volume and
control apparatus responsive to outputs from the sensor
in both of the modes of operation for preventing opera-
tion of the machinery when the presence of a user and
clothing and accouterments thereof within the predeter-
mined volume could cause injurious engagement.
Additionally in accordance with a preferred
embodiment of the present invention, the sensor comprises
at least one ultrasonic transducer.
Furthermore in accordance with a preferred
embodiment of the present invention, the sensor is opera-
tive in the reference sensing mode of operation in the
absence of a user or operator within the predetermined
volume.
Additionally in accordance with a preferred
embodiment of the present invention wherein the sensor is
operative in the reference sensing mode of operation with
generally the same frequency as it is operative in said
engagement prevention mode of operation.
Moreover in accordance with a preferred embodi-
ment of the present invention, the sensor is operative in
the reference sensing mode of operation with a frequency
much less than it is operative in the engagement preven-
tion mode of operation.
Additionally in accordance with a preferred
embodiment of the present invention, the sensor comprises
at least two sensors viewing the predetermined volume and
together providing an output indication of the location
of objects within the predetermined volume in at least
two dimensions and wherein the control apparatus is
responsive to the output indication for preventing opera-
tion of said machinery when the presence of a user and
clothing and accouterments thereof at predetermined
locations within the predetermined volume could cause
CA 02559386 2006-09-27
4
injurious engagement.
Still further in accordance with a preferred
embodiment of the present invention wherein the control
apparatus is operative to be non-responsive to predeter-
mined regions within an outer boundary of the predeter-
mined volume, corresponding to predetermined time do-
mains.
There is also provided in accordance with a
preferred embodiment of the present invention a safety
apparatus for preventing injurious engagement of machin-
ery with a user and clothing and accouterments thereof
within a predetermined volume including at least two
sensors viewing the predetermined volume and together
providing an output indication of the location of objects
within the predetermined volume in at least two dimen-
sions, control apparatus responsive to the output indica-
tion for preventing operation of the machinery when the
presence of a user and clothing and accouterments thereof
at predetermined locations within the predetermined
volume could cause injurious engagement.
Additionally in accordance with a preferred
embodiment of the present invention, the at least two
sensors comprise at least two ultrasonic transducers.
Furthermore in accordance with a preferred
embodiment of the present invention, the control appara-
tus excludes predetermined three-dimensional regions from
the predetermined volume corresponding to predetermined
combinations of different time domains of the at least
two sensors.
There is also provided in accordance with a
preferred embodiment of the present invention a door
operating system comprising an automatically operable
door, a sensor for sensing the presence of an object
within a predetermined volume located at the door of the
vehicle and above steps leading to the door of the vehi-
cle from the outside thereof, and a-door controller
CA 02559386 2006-09-27
operative at least partially in response to an output
from the sensor to actuate the automatically operable
door.
In accordance with a preferred embodiment of
the present invention the sensor is an ultrasonic sensor.
Alternatively any other suitable type of sensor may be
employed provided that it is insensitive to inputs re-
ceived from outside the predetermined volume.
In accordance with a preferred embodiment of
the present invention, the automatic door operating
system is mounted on a vehicle, such as a bus or train
and the predetermined volume is located at the steps
leading to the door from the outside thereof.
Further in accordance with a preferred embodi-
ment of the present invention, there is provided a vehi-
cle having a chassis, a body and propulsion apparatus,
the body including at least one door operating system
comprising an automatically operable door, a sensor for
sensing the presence of an object within a predetermined
volume located at the door of the vehicle and above
steps leading to the door of the vehicle from the outside
thereof, and a door controller operative at least par-
tially in response to an output from the sensor to actu-
ate the automatically operable door.
The invention also provides, according to an aspect, for a vehicle
including a chassis, a drive train, at least one door and door control
apparatus,
the vehicle comprising: at least one sensor viewing at least one region in the
vicinity of a door; logic circuitry responsive to said at least one sensor for
providing at least one region clear output signal; and automatic door opening
and door closing apparatus responsive at least to the absence of a region
clear
output signal to cause opening of the door and responsive at least to the
presence of a region clear output signal to cause closing of the door.
CA 02559386 2006-09-27
5a
The present invention will be understood and
appreciated more fully from the following detailed de-
scription, taken in conjunction with the drawings in
which:
Fig. 1 is a simplified pictorial illustration
of a bus having an automatic door operating system con-
structed and operative in accordance with a preferred
embodiment of the present invention;
Fig. 2A is an illustration of an automatic door
operating system constructed and operative in accordance
with a preferred embodiment of the present invention and
employing a single sensor;
CA 02559386 2006-09-27
6
Fig. 2B is a sectional illustration taken along
the plane 2B designated in Fig. 2A;
Fig. 3A is an illustration of an automatic door
operating system constructed and operative in accordance
with a preferred embodiment of the present invention and
employing two sensors;
Fig. 3B is a sectional illustration taken along
the plane 3B designated in Fig. 3A;
Fig. 4A is an illustration of an automatic door
operating system constructed and operative in accordance
with a preferred embodiment of the present invention and
employing three sensors;
Fig. 4B is a sectional illustration taken along
the plane 4B designated in Fig. 4A;
Fig. 4C is a sectional illustration taken along
the plane 4C designated in Fig. 4A;
Fig. 5A is an illustration of an automatic
elevator door operating system constructed and operative
in accordance with a preferred embodiment of the present
invention and employing plural sensors;
Fig. 5B is a sectional illustration taken along
plane 5B - 5B of Fig. 5A;
Fig. 6A is an illustration of a machine tool
safety system constructed and operative in accordance
with a preferred embodiment of the present invention and
employing three sensors;
Fig. 6B is a sectional illustration taken along
plane 6B - 6B of Fig. 6A;
Fig. 6C is a sectional illustration taken along
plane 6C - 6c of Fig. 6A;
Fig. 7 is asimplified block diagram illustra-
tion of circuitry employed in the apparatus of Fig. 1 in
the closing mode;
Fig. 8 is a simplified flow chart illustrating
operation of the apparatus of Fig. 7;
Fig. 9 is a simplified block diagram illustra-
CA 02559386 2006-09-27
7
tion of circuitry employed in the apparatus of Figs. 4A -
4C and 6A - 6B;
Fig. 10 is a timing diagram illustrating opera-
tion of the circuitry of Fig. 9;
Fig. 11 is a detailed flow chart illustrating
part of the operating algorithm of the safety apparatus
of the present invention; and
Fig. 12 is a general flow chart illustrating
operation of a preferred embodiment of the present inven-
tion.
Reference is now made to Fig. 1, which illus-
trates a vehicle, such as a bus 10, having a chassis 12,
a body 14 and propulsion apparatus 16. The body 14 in-
cludes at least one door operating system. In accordance
with a preferred embodiment of the invention, the door
operation system is an automatic system, comprising an
automatically operable door 18, a sensor 20 for sensing
the presence of an object within a predetermined volume
22, also termed the "protected" volume, in the vicinity
of the door, and a door controller 24 operative at least
partially in response to an output from the sensor 20 to
actuate the automatically operable door.
Alternatively, the door operation system may be
semi-automatic wherein the door controller 24 provides an
output indication to the driver, who, responsive thereto,
opens or closes the door.
In accordance with a preferred embodiment of
the invention, the predetermined volume 22 covers the
region of the door and above steps 26 leading to the
door 18 from the outside thereof and does not extend
outwardly thereof, thereby to avoid false detections of
objects or images beyond the steps.
Reference is now made to Figs. 2A and 2B, which
illustrate an automatic door operating system constructed
and operative in accordance with a preferred embodiment
of the present invention and employing a single sensor.
CA 02559386 2006-09-27
8
It may be appreciated that the single sensor, indicated
by reference numeral 20, views all of the steps 26.
In accordance with a preferred embodiment of
the present invention, sensor 20 is an ultrasonic trans-
ceiver or any other suitable sensor which transmits
energy into a volume and senses energy reflected there-
from. It is known to limit boundaries of the field of
view of such sensors by lim.iting the time duration over
which received reflected energy is taken into account, in
other words, by limiting the time window of reflected
energy from a volume thereby to define a desired protect-
ed volume.
In accordance with a preferred embodiment of
the invention, not only the boundaries of the field of
view of sensor 20 are limited, but also the internal
configuration of the protected volume is defined by
suitably limiting the time window of reflected energy.
Referring now particularly to Fig. 2B, it can
be seen that if it is desired to eliminate energy reflec-
tions from the top facing surfaces of steps 26, it is
necessary to ignore energy reflections during certain
intervals of time within the time window. These intervals
correspond to predetermined radial distance outlines from
the sensor 20 and are indicated in Fig. 2B by reference
numerals 30.
The resulting outlines of the distances corre-
sponding to the intervals are thus seen to be curved.
Within each distance outline, a corresponding top surface
32 of a step 26 is schematically drawn to illustrate that
due to the curvature of the distance outlines, the thick-
ness thereof must be sufficient to enable the outline to
enclose the entire top surface 32 of the step.
Reference is now made to Figs. 3A and 3B, which
illustrate an automatic door operating system constructed
and operative in accordance with another preferred embod-
iment of the present invention and employing a pair of
CA 02559386 2006-09-27
9
sensors 40 and 42. It may be appreciated that the pair of
sensors view all of the steps 26.
In accordance with a preferred embodiment of
the present invention, sensors 40 and 42 are ultrasonic
transceivers or any other suitable sensors which trans-
mits energy into a volume and senses energy reflected
therefrom.
In accordance with a preferred embodiment of
the invention, the internal configuration of the protect-
ed volume is defined not only by suitably limiting the
time window of reflected energy but also by triangulation
in two dimensions by virtue of the time differences in
receipt of reflections by the individual sensors.
Referring now particularly to Fig. 3B, it can
be seen that if it is desired to eliminate energy reflec-
tions from the top facing surfaces of steps 26, it is not
necessary to ignore energy reflections during full inter-
vals of time within the time window, as in the embodiment
of Figs. 2A and 2B. Only portions of these intervals,
corresponding to the width and location of the top facing
surfaces of the steps 26 need be ignored. These portions
are determined by triangulation of the outputs of the two
sensors 40 and 42 and are indicated in Fig. 3B by refer-
ence numerals 50.
Within each distance outline corresponding to
an interval outline, a corresponding top surface 32 of a
step 26 is schematically drawn to illustrate that the
location and width of the portion of the distance outline
which is ignored corresponds to the width and location of
the step and is determined by triangulation.
Reference is now made to Figs. 4A. 4B and 4C,
which illustrate an automatic door operating system
constructed and operative in accordance with another
preferred embodiment of the present invention and employ-
ing three sensors 60, 62 and 64. It may be appreciated
that the three sensors view all of the steps 26.
CA 02559386 2006-09-27
In accordance with_a preferred embodiment of
the present invention, sensors 60, 62 and 64 are ultra-
sonic transceivers or any other suitable sensors which
transmits energy into a volume and sense energy reflected
therefrom.
In accordance with a preferred embodiment of
the invention, the internal configuration of the protect-
ed volume is defined not only by suitably limiting the
time window of reflected energy but also by triangulation
in three dimensions.
Referring now particularly to Figs. 4B and 4C,
it can be seen that if it is desired to eliminate energy
reflections from the top facing surfaces of steps 26, it
is not necessary to ignore energy reflections during full
intervals of time within the time window, as in the
embodiment of Figs. 2A and 2B. Only portions of these
intervals, corresponding to the width, depth and location
of the top facing surfaces of the steps 26 need be
ignored. These portions are determined by triangulation
of the outputs of the three sensors 60, 62 and 64 and are
indicated in Fig. 4B by reference numerals 70 and in Fig.
4C by reference numerals 72.
Within each distance outline corresponding to
an interval outline, a corresponding top surface 32 of a
step 26 is schematically drawn to illustrate that the
location, depth and width of the portion of the distance
outline which is ignored corresponds to the depth, width
and location of the step and is determined by triangula-
tion in three dimensions.
Reference is now made to Figs. 5A and 5B, which
illustrate an automatic elevator door operating system
constructed and operative in accordance with another
preferred embodiment of the present invention and employ-
ing a pair of sensor 80 and 82.
It may be appreciated that the pair of sensors
view all of the threshold 84 on both sides of elevator
CA 02559386 2006-09-27
11
doors 86 and 88 as well as surface 89 of door 88 whose
energy are to be eliminated.
In accordance with a preferred embodiment of
the present invention, sensors 80 and 82 are ultrasonic
transceivers or any other suitable sensors which trans-
mit energy into a volume and senses energy reflected
therefrom.
In accordance with a preferred embodiment of
the invention, the internal configuration of the protect-
ed volume is defined not only by suitably limiting the
time window of reflected energy but also by triangulation
in two dimensions. This enables the surface 89 of the
door 88 which is in the field of view of the sensors 80
and 82 to be ignored.
Referring now particularly to Fig. 5B, it can
be seen that if it is desired to eliminate energy reflec-
tions from the surface 89 of door 88, it is not necessary
to ignore energy reflections during a full interval of
time within the time window, as in the embodiment of
Figs. 2A and 2B. Only the portions of an interval, corre-
sponding to the location of surface 89 of door 88 need
be ignored. This portion is discriminated from the return
signal by triangulation of the outputs of the two sensors
80 and 82 and is indicated in Fig. 5B by reference numer-
al 90. Reference numeral 90 labels a region between a
first position 92 of the door 89 and a second position 94
of the door 89.
Within the distance outline corresponding to a
time interval outline, side surface 89 of door 88 is
schematically drawn to illustrate that the location and
width of the portion of the distance outline which is
ignored corresponds to the width and location of the
surface 89 and is discriminated by triangulation.
Reference is now made to Figs. 6A, 6B and 6C,
which illustrate a machine tool safety system constructed
and operative in accordance with another preferred embod-
CA 02559386 2006-09-27
12
iment of the present invention and employing three
sensors 100, 102 and 104. It may be appreciated that the
three sensors view all of a workpiece region 106 which
defines a protected volume.
In accordance with a preferred embodiment of
the present invention. sensors 100, 102 and 104 are
ultrasonic transceivers or any other suitable sensors
which transmits energy into a volume and sense energy
reflected therefrom.
In accordance with a preferred embodiment of
the invention, the internal configuration of the protect-
ed volume is defined not only by suitably limiting the
time window of reflected energy but also by triangulation
in three dimensions.
Referring now particularly to Figs. 6B and 6C,
it can be seen that if it is desired to eliminate energy
reflections from workpiece region 106 and from a work-
piece support 108, it is not necessary to ignore energy
reflections during full intervals of time within the time
window, as in the embodiment of Figs. 2A and 2B. Only
portions of these intervals, corresponding to the width.
depth and location of the outer facing surfaces of the
region 106 and support 108 need be ignored. These por-
tions are determined by triangulation of the outputs of
the three sensors 100, 102 and 104 and are indicated in
Fig. 6B by reference numerals 110 and in Fig. 6C by
reference numerals 112.
Within each distance outline corresponding to
an interval outline, corresponding surfaces 106 and 108
are schematically drawn to illustrate that the location,
depth and width of the portion of the distance outline
which is ignored corresponds to the depth, width and
location of the surfaces 106 and 108 and are determined
by triangulation in three dimensions.
Reference is now made to Fig. 7, which is a
simplified block diagram illustration of circuitry em-
CA 02559386 2006-09-27
13
ployed in the automatic door operating system of Fig. 1.
An ultrasonic transmitter 150 transmits ultrasonic ener-
gy, typically having a frequency in excess of 20KHz into
the protected volume 22 (Fig 1). Reflected ultrasonic
energy from objects such as an object 151 within the
protected volume 22, is received at one or more detec-
tors 152, such as a model 400ER 250 T"' of Prowave Company of
Taiwan, which typically is sensitive only to the frequen-
cy of the transmitter 150. The transmitter 150 and the
detector 152 may be embodied in an unitary transceiver.
Preferably at least one of the transmitters 150
and detectors 152 and possibly both of them are operative
within predetermined solid angles, thereby to limit false
detections which could result from reflections of ultra-
sonic energy from outside the desired predetermined
volume.
In accordance with a preferred embodiment of
the present invention, the arrangement of the transmit-
ters 150 and the detectors 152 may enable the circuitry
of Fig. 7 to determine the location of the object by
triangulation.
The output of detector 152 is supplied to an
analog amplifier 154, which may be embodied in 3 CLC505TM
chips. The output of the analog amplifier 154 is supplied
to a threshold comparator 156, such as an LM 119TM chip,
which compares the output of detector 152 with a prede-
termined threshold.
The output of comparator 156 is supplied to
detector logi'c circuitry 160 which defines a time window
following transmission of the ultrasonic energy by trans-
mitter 150, for receipt of reflected ultrasonic energy.
This time window corresponds to distance from the trans-
mitter and is operative to define the detection volume.
The detector logic circuitry 160 is preferably embodied
in an EPM 5160TM chip commercially available from Altera of
San Jose, California.
CA 02559386 2006-09-27
14
A microcontroller 162 receives an input from a
crystal oscillator 166 which also provides an output to
detection logic circuitry 160, which is used for actuat-
ing a driver 168, which drives transmitter 150. Driver
168 is typically embodied in a MC `4452TM chip, commercially
available from MotorolaTM
Microcontroller 162 interfaces with an operat-
ing interface circuit 170. The operating interface cir-
cuitry 170 may either provide a "CLEAR" do,or closing
actuation signal directly to door controller 24 (Fig. 1)
or alternatively provides a safety indication to an
operator who operates the door controller 24.
Reference is now made to Fig. 8, which illus-
trates the operation of part of the circuitry of Fig. 7.
The functionality which will be described hereinbelow
with reference to Fig. 8 is typically carried out by
detection logic circuitry 160 and/or micro-controller
162.
A burst of typically between 4 and 10 pulses of
ultrasonic energy is directed to the protected volume 22
(Fig. 1). Following a predetermined time delay, a re-
flected energy receipt time gate is opened for receipt of
echoes of ultrasonic energy reflected from the protected
volume 22.
During the time that the reflected energy time
gate is open echoes reflected from inside the protected
volume 22 are received. These echoes preferably include
echoes received from a predetermined reference target
within the p.rotected volume 22, such as the stairs of a
bus, as well as echoes received from non-reference tar-
gets within the protected volume 22, such as persons or
their belongings within the protected volume.
The received echoes are stored and then ana-
lyzed.
Upon analysis, if all of the echo pulses re-
ceived are found to originate from a location within a
CA 02559386 2006-09-27
predetermined proximity to the reference target, the
protected volume is deemed to be clear and a "CLEAR"
signal is sent to the operator.
At this stage, a short duration pulse, typical-
ly of a duration of one microsecond, is transmitted into
the protected volume 22 in order to determine whether any
object is within the protected volume 22 but sufficiently
close to the transmitter 150 so as not to have been
detected by the longer pulses. If no echoes of the short
pulses are received within a predetermined time period
corresponding to the protected volume, an appropriate
"CLEAR" output is provided via interface 170 (Fig. 7) to
either an automatic door or an operator.
If not all of the echo pulses received are
found to originate from a location within a predetermined
proximity to the reference target, a contrary output is
provided which indicates that the doors are not to be
closed.
Reference is now made to Fig. 9, which is a
simplified block diagram illustration of circuitry em-
ployed in the automatic door operating system of Figs. 4A
- 4C. Three separate ultrasonic transducers 180, 182 and
184, each include an ultrasonic transmitter 186 which
transmits ultrasonic energy, typically having a frequency
in excess of 20KHz into the protected volume 22 (Fig 4A).
Reflected ultrasonic energy is received at three separate
detectors 188, each of which forms part of one of trans-
ducers 180, 182 and 184. Detectors 188 may be any suit-
able detectors, such as a model 400ER 250 of Prowave
Company of Taiwan, which typically is sensitive only to
the frequency of the transmitter 186.
Preferably at least one of the transmitters 186
and detectors 188 and possibly both of them are operative
within predetermined solid angles, thereby to limit false
detections which could result from reflections of ultra-
sonic energy from outside the desired predetermined
CA 02559386 2006-09-27
16
volume.
In accordance with a preferred embodiment of
the present invention, the arrangement of the transmit-
ters 186 and the detectors 186 may enable the circuitry
of Fig. 9 to determine the location of the object by
triangulation in three dimensions.
The outputs of detectors 186 are each supplied
to analog amplifiers 192, which may be embodied in 3
CLC505 chips. The output of each analog amplifier 192 is
supplied to a threshold comparator 194, such as an LM 119
chip, which compares the output of detector 186 with a
predetermined threshold.
The outputs of comparators 194 are supplied to
detector logic circuitry 200 which defines one or more
time windows following transmission of the ultrasonic
energy by transmitter 186, for receipt of reflected
ultrasonic energy. These time windows correspond to
distance from the transmitter and are operative to define
the detection volume. The detector logic circuitry 200 is
preferably embod'ied in an EPM 5160 chip commercially
available from Altera of San Jose, California.
A microcontroller 202 receives an input from a
crystal oscillator 204 which also provides an output to
detection logic circuitry 200, which is used for actuat-
ing a driver 206, which drives transmitters 186. Driver
206 is typically embodied in a MC 4452 chip, commercially
available from Motorola.
Microcontroller 202 interfaces with an operat-
ing interface circuit 208. The operating interface cir-
cuit 208 may either provide a "CLEAR" door closing
actuation signal directly to door controller 24 (Fig. 1)
or alternatively provides a safety indication to an
operator who operates the door controller 24.
Reference is now made to Fig. 10 which is a
timing diagram illustrating operation of the circuitry of
Fig. 9. Synchronization pulses, supplied by detector
CA 02559386 2006-09-27
17
circuitry in response to an input from microcontroller
202, cause the transducer driver 206 to cause the trans-
mitters 186 preferably in all three transducers 180, 182
and 184, to simultaneously transmit a burst of ultrasonic
energy pulses into the protected volume 22 (Fig. 1). The
bursts are typically of duration about 100 microseconds.
Following each burst, echoes received from the
protected volume 22 are received by detectors 188 of the
transducers 180, 182 and 184. The outputs of detectors
188 are only considered if they fall within a time window
defined by a gate interval generated by microcontroller
202. In the illustrated example of Fig. 10, the echoes of
the bursts are received at different times by different
detectors. Clearly the time of receipt by a given detec-
tor is a function of the distance of a target from that
detector. In such a way, time based triangulation is
employed to determine the location of the target in the
protected volume.
Fig. 11 illustrates the operating algorithm of
the apparatus of Fig. 9 in eliminating consideration of
echoes received from defined volumes enclosing fixed
objects within the protected volume. The protected volume
is initially viewed by three sensors and the fixed ob-
jects therein are mapped. An excluded volume is then
defined which encloses each of the mapped fixed objects.
During steady state operation of the apparatus,
echoes from both outside the protected volume and from
the excluded volumes (where an excluded volume is defined
as a legitimate region including background objects)
which enclose- the fixed objects within the protected
volume are not considered. If and only if echoes are
received from within the protected volume but outside the
excluded volumes is door closure prevented or a corre-
sponding action taken or avoided in another operational
context.
It is a particular feature of the present
CA 02559386 2006-09-27
18
invention that the apparatus of the present invention can
be used not only for preventing closing of doors but also
for automatic door opening without additional hardware.
Reference is now made to Fig. 12 which illustrates the
operation of the present invention.
As seen in Fig. 12, following initial configu-
ration of the system and definition of one or more pro-
tected volumes and excluded volumes therewithin, a vehi-
cle is operated selectably in a manual mode, wherein door
opening and closing is controlled exclusively by an
operator or in an automatic mode wherein at least one and
preferably both door opening and closing is autAatically
controlled.
Door opening may be enabled by an operator when
he reaches a station or automatically by a sensor which
senses arrival at a station and stopping of the vehicle.
In the automatic mode of operation, even after door
opening is enabled by the operator, the door will only be
opened when a target is located within a predetermined
protected volume but outside an excluded volume there-
within. In this case the target is normally part of a
passenger's body.
The same sensors and logic apparatus may be
employed for automatic door closing. When door closing is
enabled by an operator or by any other suitable automatic
or semiautomatic system, the door will only be closed
when a target is not located within a protected volume
but outside an excluded volume therewithin.
It is a particular feature of the present
invention that the protected volume for door opening need
not be identical with the protected volume for door
closing, notwithstanding that the same hardware is em-
ployed. Selection of the protected volumes may be made by
suitable calibrations or instructions given to the detec-
tor circuitry or other circuitry in the system.
It will be appreciated by persons skilled in
CA 02559386 2006-09-27
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the art that the present invention is not limited by what
has been particularly shown and described hereinabove.
Rather the scope of the present invention is defined only
by the claims which follow:
