In the year 2001, I decided to keep a very similar theme as last year, except I fully intended to qualify and WIN! Thus, the suffix on last year’s name...ARFF-TTFS (This time for sure)

Well, this entry still used the Hamamatsu detector on a servo to detect and point at the candle. It also used a Sharp GP2D02 sensor for side, front and rear distance measurement, in order to navigate he house.

The basics of the robot are similar, but the implimentation is totally different.

Drive System: First of all, I moved to DC motors over lasy year’s stepper motor drives. The steppers are low powered, and it was a constant race....make the steppers bigger, and it causes the need for a bigger battery....which then drives the need for larger steppers!

I used DC motors with an internal gearbox of something like 20:1. I bought them at Jameco on the following catalog page.

The other thing that makes this year’s robot different is the change in philosophy regarding distributed control. Lasy year, the main processor controlled everything. All aspects of control, from highest to the lowest, were handled by the PIC16C74.

In this robot, an attempt was made to distribute the control and functionality in order to allow each function to have it’s own microcontroller for the job.

Each of these microcontrollers are connected together via a simple, but proprietary interfaced which is sort of a cross of I2C and SPI. Actually, it has the addressing of I2C, with the similar speed and signal interface as a SPI interface. I call it the IPC (Inter-Processor Communication) interface.

The IPC Interface is my own design. It is intended to make wiring and communicatione between modules/processors simple.

Some of the processors poll the interface, and some operate via interrupts. The interface is designed to allow for either option.

There is a timing diagram for the IPC interface contained on page 2 of the schematic of the motor driver board.

The picture to the left shows the two motors and motor control boards to drive them. Both of them sit on a serial bus where they take commands from the main processor. (now currently a Basic Stamp.)

The front view of ARFF-TTFS shows the line detector on the front. This is used to detect the line in front of the candle so that ARFF can get within 12” as the rules require.

The circuit for this line detector is a single chip 12C508 microcontroller design. It has its own LEDs to light the floor, but the room ambient changes are totally calibrated out because the micro will take ambient light readings and factor them out.

The schematic for this simple line detector is found here.

As you can see from the front view also, I have a 3 blade propeller, which is driven by an electric RC plane motor. That combination really puts out some wind, and should take care of any candle thrown at it! Oh, BTW, the fan is actually driven by the same motor control circuit as drive the motors. The only change is that the H-Bridge used for motor drive are replaced with a high power FET that is capable of driving the 10 Amp RC plane motor.

The side view of ARFF-TTFS shows the fan, Hamamatsu, and the drive wheels. You can not see the Sharp IR Distance Sensors. These are controlled from a PIC 16C84 which sits on that serial BUS and takes commands and sends distances.

Here is the schematic for this.

This controller currently handles 4 Sharp sensors, but it is designed to read 8 sensors at a time.

The rear side of the robot s\hows the two 7.2v car batteries. This is the power source for everything including the regulators that generate the +5volts for the logic.

The results.....well, ARFF-TTFS did qualify, and came in tied for 43rd out of 54.

I was in the Senior division where 71 people initially signed up. Out of those, only 54 qualified and ran in the contest.

Here are some pictures of the contest and contestants.

Pictures #1, Pictures #2, Pictures #3

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