Rosie by Doug Oda

Dimensions:  12 inches high, 8 inches in diameter
Power:  12 "D" cell batteries
Locomotion:  Two unipolar stepper motors
Brains: 2 Phillips 87C752, 1 Motorola 68HC11F1
Fire detection: 2 EG&G Thermopiles
Fire extinguisher: Bilge pump and sprinkler head

Rosie was built in three stages and designed to compete in the fire
fighting robot contest. The first stage was a rolling base, then a
navigation section, the third was the fire detection and extinguishing
section. By building each as an individually functioning unit I was able
to cut down my development time.
The first stage consisted of two drive wheels mounted in a 8 inch
diameter Plexiglas disk on the center axis. On a perpendicular axis were
two casters. The stepper motors drove the drive wheels via a gear
mounted to each. The steppers were "stepped" using a darlington
transistor array with the stepper pattern counted off using a 87C752
microcontroller. For testing the microcontroller received a 4 bit speed
code from a temporary board mounted with switches that was later
replaced with a connection to the navigation unit. 
The navigation unit was built with a 68HC11F1 controller wirewrap board
mounted on a 8 inch diameter Plexiglas disk.  Three Omron optical
proximity switches were also mounted on the disk. The proximity switches
were used for wall detection at a range of 2 inches.  A linear encoder
and an optical detector were added to the base unit and attached to the
navigation section. The linear encoder was mounted at the exact center
of the base unit and was used to measure distance traveled. The
navigation unit was mounted to the rolling base using standoffs. The
navigation section sent spent speed and direciton information to the
base unit. A four bit code (bit3=forward/reverse, bits0-2 time delay
between stepper motor "steps") was used along with two interrupts (one
for each motor). The units were tested together and could successfully
navigate the floor plan described in the contest rules. 
The last stage built was the detection and extinguishing section. The
detection was accomplished using two thermopiles mounted on rotating
panels.  The panels were rotated using 2 stepper motors. This last
section used a 87C752 microcontroller to a) control the stepper motors
that rotated the thermopiles, b) use the onchip A/D converter to measure
voltage generated by the thermopiles, c) send a three bit direction code
to the navigation module if a candle were detected, d) turn on a bilge
pump if a signal were sent from the navigation controller. The candle
was extinguished using water pumped from a bilge pump. The water was
pumped to a sprinkler head that was attached to a linear actuator for
moving the head back and forth. The battery pack and the water tank were
a structural part of this section.
Building the robot in three parts cut down on development time as well
as providing myself with experience using       different
microcontrollers.
Problems with Rosie: There were two basic design problems with the
finished Rosie. The first was the fact that the robot was very slow. The
water tank and 12 "D" cell batteries forced the steppers to be run at a
very slow speed. The second problem was that the thermopiles did not
have a very good range. A candle could only be found at approximately 12
inches.

Email: Doug.Oda@stdreg.com


Return to The Robot Menu