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Description  |
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BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates generally to motor vehicle position indication
devices and more particularly, but not by way of limitation, it relates to
improved apparatus for maintaining indication of vehicle position to the
operator and/or for providing indication to a central location dispatching
entity.
2. Description of the Prior Art
The prior art includes various types of devices as utilized for moving
vehicles, planes, ships and the like for utilizing gyroscopic and/or rate
of speed indications. Such prior art teachings have generally been
directed to military applications such as position indication for ships
and aircraft, and such high reliability equipment has generally taken the
form of very complex computerized electronic equipment. The closest known
prior patent art appears to be U.S. Pat. No. 3,789,198 in the name of
Henson et al. There appears to be little prior art developed with respect
to relatively simplified forms of device which might be suitable for
vehicle tracking use wherein costly, high reliability space-consuming
equipment may not be justified.
SUMMARY OF THE INVENTION
The present invention contemplates a digital position keeping device which
utilizes gyroscopic and odometric inputs to continually maintain a
relative position spot indication on a video monitor disposed in the
vehicle in view of the operator. It is also contemplated that such
position indication data can be modulated and transmitted to a central
dispatching agency from one or more vehicles thereby to provide continual
indication of vehicle position to the central agency.
Therefore, it is an object of the present invention to provide a relatively
low cost vehicle position indicator.
It is also an object of the invention to provide a device for displaying
vehicle location with increased accuracy and reliability.
It is yet another object of the present invention to provide a digital
system for continually maintaining position reference of a moving
structure for monitor at a centralized agency.
Finally, it is an object of the present invention to provide a moving
vehicle indicator device which can be produced at greater economy to yield
increased reliability and accuracy.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a block diagram of a position location system as constructed in
accordance with the present invention;
FIG. 2 is a block diagram of a preferred form of the present invention;
FIG. 3 is a diagram of a microcomputer as utilized in the system of FIG. 2;
FIG. 4 is a block diagram of one form of data transmission apparatus which
may be used with the present invention;
FIG. 5 is a depiction of a video monitor overlay mask which may be utilized
in the present invention;
FIG. 6 is a plan view of a gyroscope encoding card as used in the present
invention;
FIG. 7 is a plan view of an odometer encoding card;
FIG. 8 is a schematic diagram of a digital gyroscope readout apparatus used
in the present invention;
FIG. 9 is a schematic diagram of light detector circuitry as used in the
FIG. 8 apparatus;
FIG. 10 is a schematic diagram of odometer readout apparatus as used in the
present invention;
FIG. 11 is an idealized plan view depicting a portion of an odometer
encoding card in relation to readout apparatus of FIG. 10;
FIG. 12 is a schematic diagram of the odometer control generator of FIG.
10; and
FIG. 13 is a flow diagram of a microcomputer program.
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 represents a generalized block diagram illustrating a position
location system 10 for use in moving vehicles, i.e., land, air or water
craft. The system utilizes a gyroscope 12 for referencing directionality.
An odometer 14, or similar air or water distance indicator, provides
distance data output. Thus, in its most basic form, it is the aim of the
invention to provide in a moving carrier, a video monitor indication
wherein, after initial calibration and zero adjustment by a manual adjust
16, the video monitor 18 will display an x/y coordinate movement in proper
direction and proportionate distance of travel of the carrier in which
such a system is installed. The video monitor 18 as well as other
component parts of the system are powered by a conventional form of power
supply 20 as may be operated from the conventional DC power supply on
board the carrier, e.g., in an automobile the conventional +12 volt power
supply would be utilized.
An area map overlay 22 (to be further described), as designed in
conformance to the diameter of the video monitor 18 and the range switch
capabilities, may be placed in overlay over the face of the video monitor
18 such that the system can be zeroed to control the cathode ray spot and
thereby trace the vehicle's path in relation to the map overlay 22. The
area map overlay 22 can be designed in proper size for any area of
interest once a standard calibration procedure of video monitor 18 is in
effect.
Variable outputs from gyroscope 12 and odometer 14 are further processed in
a microcomputer 24, as will be more particularly described below. Output
from microcomputer 24 is then applied to buffer and drive circuitry 26,
and digital output data from the buffer and drive circuitry 26 may then be
transmitted to a remote repeater station having a similarly calibrated
video monitor that is capable of then reproducing vehicle position at the
remote location. In this instance, the direction and distance information
is changed to pulse code modulation in a conventional modulator stage 28.
The pulse code modulation may then be transmitted via frequency modulation
in FM transmitter 30 for reception at an FM receiver 32 and subsequent
demodulation in a demodulator 34. The digital signals are once again
converted in digital/analog converter 36 for application to a cathode ray
tube repeater or video monitor 38, which, under control of the power
supply 40, provides cathode spot tracing of the carrier route. Here again,
an area map overlay 22 may be utilized at the repeater video monitor 38. A
large volume digital computer 42 may be utilized at a central location in
order to process and store greater volumes of route data for one or more
carriers.
FIG. 2 illustrates the control circuitry of the present invention in still
greater detail. The microcomputer 24 receives a plurality of input signals
such as calibration data on leads 44, azimuth data on input leads 46, and
distance data on leads 48. Additionally, range input, position set input
and true quadrant set input are provided on respective leads 50, 52 and
54. Vector data output from the microcomputer 24 is then presented on the
group of leads 56. The odometer 14 is an optical device, to be further
described in detail, wherein the odometer shaft is mechanically coupled to
an optical wheel including an encoding disk. Thus, the odometer 14
functions to allow light to become modulated at a rate proportional to the
distance travelled by the vehicle. Output from pulse generator 58 is then
applied at the rate of 100 pulses per revolution of the odometer shaft on
lead 60. A sense lead 62 is positive if the carrier is moving forward and
negative if the carrier is moving backward. Signals on leads 60 and 62 are
then applied to an up/down counter 64. The up/down counter 64 is
periodically interrogated and reset by lead inputs 66 and 68,
respectively, and proceeds at a predetermined rate, and the pulses from
the pulse generator 58 are divided by the proper integer in the up/down
counter 64 so that the data passed to the microcomputer 24 can be handled
as calibrated distance information.
The digital gyroscope 12, to be more fully described below, is so
constructed that a nine bit digital word can uniquely specify the azimuth
to the nearest degree. The digital word output via line 70 is applied to
an azimuth data buffer 72 which conditions the nine bit word so that it is
thereafter electrically compatible with the microcomputer 24. A manual
adjust 16 receives an analog voltage from the voltage divider 74 for
direct application to an analog/digital converter 76. If the
analog/digital ready line is asserted, the data from the analog/digital
converter 76 may then be used as a correction signal to calibrate azimuth
data, as input via lead group 44.
A range switch 78 serves to define for the microcomputer 24 the proper
integer effective in counter 64 and thereby allows the distance
information to agree with the scale associated with the map overlay at
video monitor 18. A true quadrant set switch 80, when asserted by the
operator, will indicate to the microcomputer 24 to treat the digital word
which is presently contained in the azimuth data buffer 72 as being in the
closest quadrant. Position set switch 82 allows the operator to move the
current "home position" or other central designation of the field monitor
in both the x and y directions. By using this positioning switch 82, the
operator can force the "home position" to coincide with his current
location if so desired.
All input signals to the microcomputer 24 provide the necessary raw data to
make intelligent position calculations. Microcomputer 24 can sample the
distance information and azimuth information at a rapid rate thereafter to
make the necessary calculations to determine a location vector. A current
home position when modified by a location vector then becomes the new home
position. Of course, the microcomputer 24 continues to make iterations
such that the home position will always be as accurate as the previous
calculation. The location vector information is passed as a digital word
via lead group 56 to the vector buffer and drive circuitry 84 where it is
properly formatted electrically to interface with the video monitor 18.
Additional software treatment maybe provided in order to scan all of the
input switches previously described, and thereafter make the proper
decision called for by each switch.
The output from the microcomputer 24 is a vector in the form of a digital
word on lead group 56. This digital word, which contains both distance and
azimuth information, is properly formatted by the vector buffer and drive
circuitry 84. The formatted output signals on leads 88 and 90 may then be
applied to the transmitter 30 circuitry (FIG. 1) to be telemetered to a
remote location, as well as to the video monitor 18. The video monitor 18
is capable of tracking the carrier at any instant as well as to display
selected alpha-numeric information if necessary.
FIG. 3 illustrates the microcomputer 24 in greater detail. The
microcomputer 24 is made up of standard modular integrated circuits,
hereinafter referred to as ICs. Unless otherwise noted, the IC-type chips
referred to are Intel, commercially available from the Intel Corporation
in Santa Clara, California.
A clock generator 102, IC-type 8224, provides timing signal input at 18 MHz
by a line 98 to the clock input of central processing unit 100, IC-type
8080. The 8 BIT central processing unit 100 is the heart of the
microcomputer, as it provides the necessary computational power to collect
directional data from the gyroscope 12 and the odometer 14, and thereafter
output the resultant direction vector as digital words to the vector
buffer and drive circuitry 84 (FIG. 2). All communication with the central
processing unit 100 is carried out along an 8 BIT data bus 102 from a data
bus controller 104, IC-type 8228. The data bus controller 104 provides
buffering between the central processing unit 100 and each of the 512 BYTE
read only memory 106 and the 512 BYTE random access memory 108. The read
only memory 106 consists of two parallel arrayed 2K reprogrammable PROM'S,
IC-type 8702, and the random access memory 108 is made up of four parallel
arrayed IC-type 2112-2, a 1024 static MOS RAM with common data
input/output.
Communication between data bus controller 104 and memories 106 and 108 is
made via data bus 110 which is also applied to a bi-directional data bus
driver 112, two IC-type 8216 in parallel. Data bus driver 112 provides 8
BIT output via lines 114 to provide additional drive capability to
interface with other memory devices, other hardware and the like. The data
bus controller 104 is also connected via line 116 through a tri-state
driver 118 to provide four control signal outputs via lnes 120, and these
function to strobe memory or input/output data to the data bus driver 112.
The tri-state driver 118 is an IC-type 74LS125, and output via lines 120
serve to control any peripherals which may be generating 8 BIT word input
to data bus drivers 112.
The central processing unit 100 addresses the memory of the input/output
devices along the 16 BIT address bus 122 to the tri-state address bus 124,
i.e., five parallel arrayed IC-types 74LS125. The address bus driver 124
provides the necessary three-state drive capability. The eight least
significant bits (LSB) are directed via lines 126 and 128 to the memory
address inputs on respective read only memory 106 and random access memory
108, while the eight most significant bits (MSB) are applied via line 130
for decoding in a memory selector 132, a high speed one-of-eight binary
decoder, IC-type 8205.
The power-up sequence and initialization program are contained in standard
8 BIT format form in the 512 BYTE read only memory 106. The 512 BYTE
random access memory 108 is provided as a scratch pad to store
computational results and variables that are then called upon for use by
the central processing unit 100.
Referring now to FIG. 4, distance and azimuth information on lead groups 46
and 48 (FIG. 2) may be applied in conventional manner to a time multiplex
sampling circuit 140 which functions to periodically sample the input
information in time successive manner. A sampling rate generator 142 then
provides pulse outputs at requisite rate to control the sampling rate and
duration within time multiplex sampling circuit 140. The output from the
time multiplex sampling stage 140 is then applied to a pulse code
modulation stage 144 for conventional digital signal modulation whereupon
the code modulated output on a line 146 is applied to FM transmitter 148
for energization of the transmitting antenna 150. The FM transmitter 148
would preferably include a crystal controlled output oscillator of
characteristic frequency and identifying a particular vehicle or carrier
by frequency allocation.
A central receiver station, such as that shown in FIG. 1, may include FM
receiver 32 or a plurality of such receivers each tuned to a
characteristic frequency identifying a selected vehicle in the area. Upon
demodulation and establishment of the distance and azimuth information, a
plurality of individual video monitors may be utilized, each monitor
identifying a selected vehicle of the fleet. The position data
information, i.e., distance and azimuth information, can alternately be
applied to the computer 42 which may be properly programmed to maintain
position identification of all vehicles or carriers in the area and which
may also receive other input relative to the vehicle for associated
storage in computer 42. Thus, by proper utilization of the computer
storage, a printout for a particular vehicle over a selected period of
time may be acquired in order to verify or provide a complete routing of
where the particular vehicle traveled during its on-duty usage.
FIG. 5 illustrates a typical form of map overlay 152 which may be formed of
clear plastic material to include map linings defining city limits 154,
major highway 156 and/or other landmark or central locations as desired.
The radius of the video monitor as shown by arrow 158 must be matched to
the map overlay radius, and a multiple of map overlays 152 of different
calibrated radii may be employed, one for each step of the range switch 78
(FIG. 2).
FIG. 6 illustrates an optical encoding disk 160 as used in the digital
gyroscope 12 (FIG. 2) in the present system. The encoder disk 160 carries
transparent/opaque markings about its circumfery and, beginning at
0.degree. as noted by arrow 162, it provides a binary coded decimal count
in 360 increments therearound. Thus, for every integral degree in the
360.degree. circumfery there is a 9 BIT binary output indicative of that
degree. Output from the odometer 14 (FIG. 2) is also taken by optical
viewing of an encoding disk 164 as shown in FIG. 7. The encoding disk 164
carries about its circumfery a ring 165 consisting of a plurality of
equi-spaced transparent/opaque markings, each of arcuate length selected
consonant with system accuracy.
Referring to FIG. 8, the gyroscopic encoder disk 160 (FIG. 6) is carried on
a suitable reflector platform 166 receiving rotation from a conventional
form of gyro 168 and rotational output shaft 170. A plurality, in the
present case nine, of optical fiber pairs 172 are then maintained in
radial alignment relative to encoder disk 160 to provide readout of the
binary code. A suitably secured brace 174 supports a plurality of plastic
holder blocks 176, and each plastic block 176 maintains a fiber optic pair
178 in reading position over a selected binary annulus of encoder disk
160. In this case light reflective phenomena is utilized, and a light
source 180 provides input light to respective optic fibers 182 while the
reflectivity at encoder disk 160 is read by the respective optic fibers
184 for input to a light detector 186.
FIG. 9 illustrates light detector 186 in greater detail. As previously
stated, there are in the present case nine such reflective light optical
fibers 184 and each is ready by a respective photo Darlington transistor
circuit 187. The photo Darlington transistor arrays are of commercially
available type and include a light responsive NPN transistor 188 connected
in cascade with a common-emitter NPN transistor 190. Emitter output is
taken via lead 192 for amplification in a conventional integrated circuit
amplifier 194 to provide output on a respective lead 196 within lead group
70 (FIG. 2). Thus, a plurality of outputs on leads 196 provide a 9 BIT
binary word for application through azimuth data buffer 72 to
microcomputer 24 for each degree from 1 through 360.
FIG. 10 illustrates the odometer 14 and readout apparatus utilizing the
encoder disk 164 (FIG. 7). Here again, a reflective platform 200 receives
selective directional rotation from odometer 14, and the respective
encoding ring 165 of disk 164 is read by two optical fiber pairs as
rigidly affixed in a plastic holder block 202 supported by a brace 204.
Here again, a light source 206 provides input light via optical fibers 208
and 210 to the block 202, and readout of light reflective characteristics
are via respectively paired optical fibers 212 and 214 to control
generator 216. Control generator 216 actually constitutes the input
portion of the pulse generator stage 58 in FIG. 2. The optical bundle
holder block 202 is positioned on brace 204 so that it maintains the
optical fiber pairs 218 and 220 oppositely offset from a common radius of
encoder disk 164, as shown in FIG. 11. Thus, block 202 maintains the
optical fiber pairs 218 and 220, as shown by A and B, in diagonal corners
over the area of an indicator block of encoder disk 164. The diagonal
disposition enables determination of not only rate of movement but also
direction of movement (forward or reverse), as will be further described
below.
Referring to FIG. 12, each of the A and B reflected light optical fibers
212 and 214 is readout by a respective photo Darlington transistor circuit
222 and 224 to provide emitter outputs via leads 226 and 228 for
processing in the NAND logic circuitry of control generator 216. Thus,
pulse indication on lead 226 is applied to a NAND gate 230 with output
applied to NAND gates 232 and 234. In like manner, data pulse indication
on lead 228 is applied through NAND gate 236 with output applied to NAND
gate 234 and NAND gate 238. NAND gates 232 and 238 are further controlled
by the output from NAND gate 234 as present on a lead 240 as enabling and
latching control. Pulse indication from NAND gates 232 is then applied
through an inverter 242 for input to a NAND gate 244, and output from gate
238 is applied through inverter 246 to a NAND gate 248. Each of NAND gates
244 and 248 receive further latching control input from respective leads
250 and 252 from the respective output NAND gate latching combinations 254
and 256. Thus, output pulse indication of clockwise direction (vehicle
forward) is provided on lead 258 and pulse output indicative of
counterclockwise or vehicle reverse direction is output on lead 260.
The NAND logic circuitry determines both direction and rate of movement of
encoder pattern 165 beneath block 202 (FIG. 11). In vehicle forward, the
encoder disk 164 moves in the clockwise direction to provide A to B
transitions; that is, movement of white to black results in an A
.multidot. B logic indication on respective fibers 212 and 214, with
susbsequent logic control providing clockwise output on lead 258 at a
pulse rate consonant with rate of rotation of encoder disk 164. In vehicle
reverse, the white to black transitions will be indicative of B .multidot.
A logic indication at respective optic fibers 214 and 212, and thus bring
about the opposite logical conclusion with repetitive pulse output on lead
260.
In operation, at some starting point the vehicle operator will adjust his
video monitor spot for placement at his location. This is done by
initializing the system with adjustment of range switch 78, position set
switch 82 and true quadrant set switch 80 (FIG. 2) relative to his
particular area as represented on map overlay (FIG. 5). Final position
adjustment is made by manual adjust 16 to provide calibration data input
to the microcomputer 24 (FIG. 2). Switch 80 resets any cumulative gyro
error.
Thus, initialization adjustment will move the spot indicator from a video
monitor center point 270 eastward and north to a vehicle location starting
point 272. Thereafter, tracking movement of the vehicle, the circuitry
will automatically track and control spot indicator movement as the
vehicle would proceed eastward along indication 274 and north along
superhighway 156 until the vehicles turns west on routing 276 to arrive at
a point 278. Such spot movement can be observed by the operator of the
motor vehicle in which the video monitor is installed or, the same data
can be transmitted via a transmitter system as shown in FIG. 4 to provide
such surveillance data to a central location, e.g., a police or tax cab
dispatching agency. As previously discussed, the same information can be
continually input for storage in a general purpose computer 42 (FIG. 1)
such that an on-duty route of one of the vehicles can always be recalled
from storage and printed out to show the vehicle movement during its
entire duty tour.
Referring again to FIG. 2, after initialization and during vehicle
movement, input data from odometer 14 and digital gyroscope 12 are applied
in proper format to the microcomputer 24 which is controlled in accordance
with a resident program carried by the read only memory circuit 106
therein. Programming of the Intel-component microcomputer 24 is carried
out in well-known manner to provide the requisite data analysis,
calculation and processing functions which provide final output of vector
data via lines 56 through vector buffer and drive circuitry 84 to provide
spot indicator control on video monitor 18.
FIG. 13 represents a flow diagram illustrating the general data processing
to be accomplished in microcomputer 24 by the 8 BIT format programming
present on read only memory 106 (FIG. 3). Initialization is carried out
from the read switch setting stage 280 for introduction to a decision
stage 282 to determine whether or not video monitor dot calibration is
required. If not, processing proceeds to stage 284 for initialization of
the odometer interface in accordance with the selected video monitor
range. If calibration is required in decision stage 282, it is necessary
to manually adjust the spot position as indicated by flow stage 286.
After initialization of the odometer range scale, gyroscope reading input
is received in accordance with flow stage 288 with subsequent computation
of an average gyro reading in stage 290. Next occurs a decision stage 292
which queries as to whether or not the odometer interface interrupt has
occurred. If not, the switches are scanned to determine a reset condition
as per stage 294 with data flow back to the input gyro reading stage 288.
If the odometer interface interrupt has occurred, flow proceeds to
processing stage 296 to effect reinitialization of the odometer interface.
The data at this point is then continually subject to updating of vehicle
position internally as per stage 298 whereupon a decision stage 300
queries as to proper position of the video monitor spot indicator and
whether or not it requires update. If not, flow proceeds to end stage 302
which signifies return to base loop. If spot indicator position does
require update, such update is effected in flow stage 304 prior to
processing through the end stage 302. Such data processing maintains the
video monitor spot indicator continually in position of the vehicle travel
as is directly indicated relative to the map overlay, as shown in FIG. 5.
The foregoing describes a novel vehicle tracking and indication system
which can be constructed and utilized with relatively much greater economy
than presently known direction and location systems. In addition, the
system has capability of being used for leisure time tracking or auto
amusement as well as service vehicle tracking, and various applications
wherein it is desirable to maintain position and route knowledge relative
to a plurality of vehicles. It is also contemplated that the device can be
used with emergency vehicles who must travel at increased speed through
downtown areas, as the central indication will provide the dispatching
agency with forewarning in order to change traffic lights or otherwise
clear the emergency route. Still other forms of mass transit vehicle
systems presently in genesis may well employ the present invention and
equivalents for position keeping and system surveillance.
It should also be understood that the use of the term vehicle in the
present application is employed in its true sense to mean any carrier or
conveyance. Therefore, it is well within contemplation of the present
invention that such tracking apparatus will find particular application
for use in aircraft and marine small craft. In such applications, obvious
changes are necessitated by employing an air speed type of indicator
device in place of the described odometer and, in marine applications the
similar basic sensor adjustment would be made with substitution of water
volume and rate measurement.
Changes may be made in the combination and arrangement of elements as
heretofore set forth in the specification and shown in the drawings; it
being understood that changes may be made in the embodiments disclosed
without departing from the spirit and scope of the invention as defined in
the following claims.
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