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Description  |
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FIELD OF INVENTION
This invention relates to a power-up sequencing apparatus for succesively
energizing a plurality of associated subsystems in a host system, and more
particularly to such an apparatus for use in a vehicle such as a mobile
robot.
CROSS-REFERENCE
The following applications, filed concurrently herewith, are incorporated
herein by reference:
______________________________________
Attorney's
Inventors Title Docket No.
______________________________________
Maddox et al.
Intrusion Detection System
DMR-101J
Muller et al.
Ultrasonic Ranging System
DMR-102J
Benayad-Cherif
Position Locating System
DMR-103J
et al. for Vehicle
Maddox et al.
Beacon Proximity Detection
DMR-105J
System for Vehicle
Kadonoff et al.
Orientation Adjustment System
DMR-106J
and Robot Using Same
Kadonoff et al.
Obstacle Avoidance System
DMR-107J
Kadonoff et al.
Beacon Navigation System and
DMR-108J
Method for Guiding a Vehicle
George II et al.
Recharge Docking System
DMR-110J
for Mobile Robot
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BACKGROUND OF INVENTION
Proper power-up sequencing is an ever-present problem with computers and
complex systems. If subordinate systems are energized before controller
systems the unsupervised subordinate systems may respond to false signals
and injure themselves or other components or cause control loop errors or
even endanger personnel. In autonomous mobile robots, if the drive motor
amplifier is energized before the motor controller, the drive motor
amplifier will not be supervised and may see noise which it interprets as
a drive command. The robot may as a result dash off at high speed, in any
direction, completely uncontrolled. The steering motor for the wheels must
be under control before the drive motor can be activated or a moving robot
without steering will be loosed. With certain amplifiers the bias must
arrive close to the power or the amplifier may destroy itself. If
subordinate systems power-up before control systems, then the subordinate
systems may be actively, wastefully, dangerously executing false commands.
Servo-control loop errors can lock up the robot when it tries to achieve
unrealistic goals set by the false commands, to the extent that the robot
shuts down and skilled personnel have to become involved to remedy the
situation.
One approach to the problem is to simply build time delays into each
different piece of equipment so that each turns on at a predetermined
time. One problem with this approach is that the arrival of the time gate
for turning on any particular component does not assure that previous
windows arrived on time and that power was indeed supplied to the
attendant equipment.
SUMMARY OF INVENTION
It is therefore an object of this invention to provide an improved power-up
sequencing apparatus for temporally spacing the turning on of related
subsystems.
It is a further object of this invention to provide such a power-up
sequencing apparatus which accurately and reliably controls the timed
energizing of related subsystems.
It is a further object of this invention to provide such a power-up
sequencing apparatus which cannot turn on the next subsystem in the series
unless the previous subsystem has been first turned on.
It is a further object of this invention to provide such a power-up
sequencing apparatus for use in a mobile robot or other vehicle.
This invention results from the realization that a truly effective power-up
sequencing of related subsystems can be effected with a series of
switching circuits, one associated with each subsystem, which responds to
a start command after a short delay by passing on the start command but
only when its own subsystem has been energized.
This invention features a power-up sequencing apparatus for successively
energizing a plurality of associated subsystems in a host system. There is
a series of interconnected sequencing circuits, each sequencing circuit
being interconnected with a subsystem. Each sequencing circuit includes
first switching means responsive to an initial system power-up for
disabling its associated subsystem; second switching means responsive to
an initial system power-up for suppressing the start command to the next
sequencing circuit in the series; and third switching means responsive to
a start command for operating the first switching means to enable its
associated subsystem and for operating the second switching means to
introduce a start command to the next sequencing circuit in the series.
In a preferred embodiment there are time delay means for delaying arrival
of the start command at the third switching means.
In addition, the entire power-up sequencing system may be used in a vehicle
such as a mobile robot having drive wheels, a drive motor, a steering
motor and control modules for operating the motors.
DISCLOSURE OF PREFERRED EMBODIMENT
Other objects, features and advantages will occur from the following
description of a preferred embodiment and the accompanying drawings, in
which:
FIG. 1 is an axonometric view of a robot incorporating the power-up
sequencing apparatus according to this invention;
FIG. 2 is a simplified exploded view with parts removed of the robot of
FIG. 1;
FIG. 3 is a block diagram of the electronic modules included in the robot
of FIGS. 1 and 2;
FIG. 4A is a plan view of the fields of view of the ultrasonic, infrared,
and microwave sensors of the robot of FIG. 1;
FIG. 4B is a side elevational view taken along line 4B--4B of FIG. 4A,
showing the vertical profile of the fields of view;
FIG. 5 is a block diagram of the power-up sequencing apparatus according to
this invention; and
FIG. 6 is a more detailed circuit schematic of a power-up sequencing
circuit of FIG. 5.
There is shown in FIG. 1 a vehicle, robot 10, according to this invention
including a head section 12 and a base 14 movable on three wheels, only
two of which, 16, 18, are visible. The wheels are mounted in three
steerable trucks, only two of which, 20 and 22, are visible. There are
twenty-four ultrasonic transducers such as the electrostatic transducer of
the Sell type available from Polaroid equally spaced at fifteen degrees
around the periphery of base 14. Above that on reduced neck 26 there are
located six passive infrared motion detectors 28, 30, 32, 34, 36, 38, only
two of which, 28 and 30, are shown. These detectors are equally spaced at
sixty degrees apart and may be DR-321's available from Aritech. Just above
that are two conductor bands 50 and 52 which are used to engage a charging
arm for recharging the robot's batteries. Head section 12 is mounted to
base 14 and rotates with respect to base 14 about a central vertical axis.
Head section 12 carries an RF antenna 65 for sending and receiving
communication signals to a base location or guard station. Head section 12
also includes an infrared sensor 68 for sensing radiation in the near
infrared region, e.g., 904 nanometers, such as emitted from LED 62 of
beacon 64, one or more of which are mounted on the walls in the space to
be protected by robot 10 to assist in locating and directing robot 10 in
the area in which it is to patrol. An ultrasonic transducer 66 similar to
the transducer 24 used for maneuvering and avoidance may be provided for
ranging. There is also provided a passive infrared sensor 68 similar to
sensors 28-38. A microwave transmission and reception antenna 70 and a TV
camera 72 which may be turned on when an apparent intrusion has occurred
are also included in head 12.
Base 14, FIG. 2, includes a main chassis 80 which carries three batteries
82 such as Globe 12 V, 80 AH Gel cells, only one of which is shown. When
fully charged they will operate the robot for twelve hours or more. Trucks
20 and 22, with wheels 16 and 18 respectively, are suspended from chassis
80. Each truck as indicated at truck 20 includes a right-angle drive 84
which receives input from vertical drive shaft 86 and provides output on
horizontal drive shaft 88, which operates pulley or sprocket 90, which in
turn through belt 92 drives pulley 94 attached to the axle of wheel 16.
Vertical drive shaft 86 and counterpart drive shafts 96 and 98 are driven
by their respective sprockets or pulleys 100, 102, 104 which in turn are
driven by endless belt 106 powered by the pulley 107 on output shaft 108
of drive motor 110 mounted beneath chassis 80. An encoder 111 mounted with
motor 110 monitors the velocity of the robot. An idler wheel 112 is
provided to maintain proper tension on belt 106. Three additional shafts,
only one of which, 99, is shown, concentric with shafts 86, 96 and 98,
respectively, are driven by a second set of pulleys or sprockets 120, 122,
124 engaged with drive belt 126 powered by sprocket 128 driven by steering
motor 130 mounted beneath chassis 80. Idler pulley 131 is used to maintain
tension on belt 126. An encoder 132 is associated with steering motor 130
to provide outputs indicative of the steering position. The steering motor
shaft is connected through pulley 128 to extension shaft 134, the top of
which is provided with a flange 136 with a plurality of mounting holes
138. Electronic chassis 140 is mounted by means of screws 142 on three
shorter standoffs 144. Three holes 146 in electronic chassis 140
accommodate the pass-through of longer standoffs 148, which mount neck 26
by means of screws 150. Electronic chassis 140 contains all of the
electronic circuit boards and components such as indicated at items 152
that are contained in the base 14, including the power cage described
infra.
When an electronic chassis 140 and neck 26 are mounted on their respective
standoffs, extension shaft 134 and flange 136 and the associated structure
are accommodated by the central hole 160 in electronic chassis 140 and the
opening in neck 26 so that the head plate 170 may be mounted by means of
screws 172 to threaded holes 138 in flange 136. In this way the entire
head rotates in synchronism with the trucks and wheels as they are steered
by steering motor 130. In addition to the primary microwave sensor 70
there are three additional microwave sensors 190, 330, 332, only one of
which, 190, is visible spaced at ninety degrees about head plate 170
mounted in housings 192, 194, and 196. Housing 194 which faces directly to
the back of the head as opposed to primary microwave sensor 70 which faces
front, also contains a second infrared sensor 334, not visible, which is
the same as infrared sensor 68. Cover 200 protects the electronics on head
plate 170. All of the electrical interconnections between head 12 and base
14 are made through slip rings contained in slip ring unit 202 mounted
about extension shaft 134 in base 14.
There are a number of subsystems in the robot. Head 12, FIG. 3, includes
three electronic portions: beacon module 210, head ultrasonic module 212,
and intrusion detection module 214. Beacon module 210 responds to the head
IR sensor 60 to determine what angle the beacon 64 is with respect to the
robot. That angle is fed on bus 216 through the slip ring unit 202 to the
main CPU 218. Head ultrasonic module 212 responds to ultrasonic transducer
66 to provide ranging information on bus 216 to CPU 218. Intruder
detection module 214 responds to the four microwave sensors 70, 190, 330,
332, and the two IR sensors 68, 334 to provide indications as of yet
unconfirmed intrusion events. These events are processed by the alarm
confirmation unit 220 in CPU 218 to determine whether a true confirmed
intrusion has occurred. In the body section 14, there is included status
module 222, mobile module 224, body ultrasonics module 226, power cage
227, and CPU 218. Status module 222 responds to the six infrared sensors
28-38 to provide an indication of an intrusion. Status module 222 may also
monitor fire and smoke detectors, diagnostic sensors throughout the robot,
as well as chemical and odor detectors and other similar sensors. Mobile
module 224 operates and monitors the action of drive motor 110 and
steering motor 130. The twenty-four ultrasonic transducers 24 provide an
input to the body of ultrasonic module 226, which guides the movement and
obstacle avoidance procedures for the robot. Power cage 227 draws on the
batteries and controls the sequencing of power to the subsystems. Finally,
body 14 contains CPU 218, which in addition to the alarm confirmation unit
220 also interconnects with a floppy disk controller, two-channel serial
I/O boards, and a reset board which receives inputs from a pushbutton
reset and CPU218 and outputs ultrasonic resets, motor resets, status
resets, beacon resets, I/O module resets and head ultrasonic resets. CPU
218 also sends and receives communication using RF antenna 65 and RF
circuit 240.
A top plan view of the fields of view of the various sensors and
transducers is shown in FIG. 4A. The twenty-four ultrasonic transducers 24
have a complete 360.degree. field of view 300. The six infrared sensors
28, 30, 32, 34, 36, 38, on body 14 provide six triangular fields of view
302, 304, 306, 308, 310 and 312. The two infrared sensors 68 and 334 on
head 12 provide the narrower fields of view 314 and 316, and the four
microwave transducers 70, 190, 330, 332 provide the four fields of view
318, 320, 322 and 324. The vertical profile of these fields is depicted in
FIG. 4B. The field of view of the microwave transducers extends
approximately one hundred fifty feet. That of the infrareds in the head
extend about thirty feet, those of the infrared in the body about five
feet, and the ultrasonics in the body also extend about twenty-five feet.
The power-up sequencing apparatus of this invention is included in power
cage 227, FIG. 5, for which the primary source is three batteries 82, 82a
and 82b, typically 12-volt, 80 amp-hour storage batteries which are
connected in series between the negative bus 356 interconnected with
chassis ground 357 through resistor 359 and one-amp fuse 361, and with the
positive bus 358. The batteries are charged through re-charge contacts
360, 362 and fuse 364. Switch 366, when closed, provides twelve,
twenty-four and thirty-six volts to main bus 358 through reverse voltage
and fuse protection circuit 368. Power cage 227 includes six power units
370, 372, 374, 376, 378, and 380.
Each of power units 370-378 includes a reverse voltage and fuse protection
circuit 382. In addition, power units 370-376 include RF filters 384. Each
of power units 370-376 also includes a DC to DC converter 386, each of
which provides a d.c. output to its associated subsystems.
When the system is initialized by the closing of switch 366, thirty-six
volts on line 390 are delivered through 10K resistor 392 to power-up
sequencing circuit 394 in power unit 370. After a short period of time
power-up sequencing circuit 394 energizes its associated converter 386,
which supplies power to the serial bus interface, the motor amplifier
bias, and the steering amplifier bias, block 395. After that occurs a
start command is sent on line 396 to power-up sequencing circuit 398,
which after a short period of time energizes its associated DC to DC
converter 386, which powers up the main CPU 218, block 399. After this, a
start command is sent on line 400 to power-up sequencing circuit 402,
which then energizes its associated converter 386. This converter powers
up the mobile module 224, the status module 222 and the body ultrasonic
module 226, block 403. After converter 386 is energized, a start command
is sent on 404 to power-up sequencing circuit 406, which in turn energizes
its associated converter 386 to provide power to the body transducer
control modules, block 407. Following energization of its associated
converter, power sequencing circuit 406 sends a start command on line 408
to power sequencing circuit 410, which immediately enables steering
amplifier 412 since the bias has been previously supplied as indicated in
block 395, so that amplifier 412 now provides an output from its
controller, mobile module 224, to the steering motor. After this, power-up
sequencing circuit 410 provides a start command on line 413, which causes
power-up sequencing circuit 414 to energize the system logic card 416.
This provides the final initialization of the circuit by sending signals,
for example, to an eight-bit parallel input/output device to the
microprocessor in module 224, the battery voltage and drive motor current
monitoring system, the emergency stop switches, the system reset bus, the
manual control joysticks, and finally an enable signal to the motor
amplifier 420, which has previously been provided with a bias on bus 358
as indicated in block 395, so that the robot is now able to move. Should
any one of the subsystems not be powered up, its associated power-up
sequencing circuit would not propagate the start command and the following
units would not be energized.
The power-up sequencing achieves orderly initialization. The serial bus
interface is turned on first so that the various modules 210, 212, 214,
222, 224, 226 can talk to each other. The motor amplifier bias and the
steering amplifier bias are turned on at this early stage to prevent
damage to the amplifiers and also to eliminate motor control loop errors.
In the next stage, block 399, the main computer is turned on since it is
the top of the hierarchy and the highest command source, and once it is
on, spurious commands will be prevented from misleading the subordinate
units. Next, in block 403 the mobile module is turned on along with the
status module and the ultrasonic body module as they are subordinate to
the CPU and are now safely energized. In the fourth stage, block 407,
transducer control modules are then energized. In the fifth stage the
steering power amplifier is energized. This must be done before the drive
motor amplifier is turned on. Finally the system logic card is powered up
to enable various monitoring systems, diagnostics and the like, and to
finally enable the drive motor amplifier so that the robot now has motive
power.
Each power-up sequencing circuit is constructed as indicated with respect
to circuit 394 as shown in FIG. 6. When switch 366, FIG. 5, is closed,
thirty-six volts are applied to line 390 and through resistor 392 and
resistor 460 to the base of transistor 470. Capacitor 464, discharged,
holds transistor 470 off, and point 472 is now free to bias transistors
452, 454 on. When transistor 452 conducts it connects line 456 to ground,
thereby inhibiting the operation of DC converter 386. When transistor 454
conducts, it brings point 458 to ground and thereby suppresses the start
command on line 396 to the next power-up sequencing circuit 398. However,
when the start command arrives on line 462 it immediately begins to charge
capacitor 464 through resistors 460. Resistors 466 and diode 488 are
provided for discharge of capacitor 464 when the system is turned off. At
this point, when capacitor 464 charges sufficiently it provides a bias on
the base of transistor 470, which causes it to conduct. When it conducts
it draws point 472 to ground and thereby shuts off both transistors 452
and 454. Thus simultaneously the signal on line 456 is allowed to rise so
that DC converter 386 is no longer inhibited from operation, and point 458
also rises to generate the start command to the next power sequencing
circuit in series, in this case circuit 398. In each subsequent circuit
there is no input from resistor 392; there is only a start command
generated by the previous power-up sequencing circuit.
Although specific features of the invention are shown in some drawings and
not others, this is for convenience only as each feature may be combined
with any or all of the other features in accordance with the invention.
Other embodiments will occur to those skilled in the art and are within the
following claims:
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