A power-up sequencing apparatus for successively energizing a plurality of associated subsystems in a host system, including a series of interconnected sequencing circuits, each sequencing circuit interconnected with a subsystem and including 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.

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 
______________________________________ 
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.

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: