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Bob Proctor, Maple Grove, MN
Ham License: N6YPE
This name seemed like a natural. It pays homage to my favorite 8-bit
processor series, Atmel's AVR. Not to be confused with Dr. Who's nemesis,
- Type: Rover, differential drive, with pivoting castor at the front.
- Purpose: To be an exhibition robot. With flashing lights and speech
effects, it is designed to attract attention and stimulate curiosity.
- Controller: Atmel ATTINY26 and ATMega162 microcontrollers. The
Mega162 is used as the master controller, for higher-level control, the
Tiny26's are distributed for dedicated functions and they are connected
together with an I2C bus. This will allow me to add functions later,
without taxing the main processor very much. I use these very simple
building blocks, because they are inexpensive, they don't need a crystal to
run up to 8MHz, they have in-system reprogrammable flash, and there are free
tools for development. This makes for easy evolution, assuming I want to
- Software Development Environment/Methods: Atmel's AVR Studio
development environment (free), CodeVision AVR C-Compiler (free version),
and beginning to work with WinAVR (a.k.a. AVR-GCC, also free). I like the
idea of using free tools, not just because I'm cheap, but because it is
easier for others to try it without serious investment. There is something
to be said, however, for a good, fully-paid-for-and-fully-capable compiler.
- Sensors: Primary obstacle detection will be done with ultra-sonic
sonar. One front-facing emitter in the center will emit a short pulse, two
receivers on either side of the front will detect the echo. As a backup,
there will also be IR emitter/detectors off the corners, and PVC pipe
bumpers, sensitive to which side the collision happened.
- Actuators: No actuators are planned, but with a clear plastic dome,
it will enclose a circular array of bright LED's for fancy light flashing.
This could make the machine more interesting to look at, as well as showing
the "mood" of the machine (moods could be exploring, fleeing, seeking,
panic, warning, battery warning, etc.). The LED array will provide visual
feedback of what the sensors are seeing, to make development easier. A
sound playback chip will emit short messages.
- Height, width, length:About 7"Hx15"Wx18"L. Bound to change with
- Weight:About 15 pounds.
- Power source: Two 12 volt sealed lead-acid batteries (Gel Cells)
wired in series for 24V. Primary power will be available to the motor
controls, some will be down-converted to 5V for the logic. Power drain to
be determined, but the motors were chosen specifically for their efficiency,
and the down-converter will be a DC-DC. The batteries will have access
jacks on the robot enclosure to allow charging without opening the case.
- Speed: I expect about 2MPH, maybe a lot less, depending on the
effectiveness of the obstacle avoidance.
- Contruction history: The construction decisions were partially
based on observations of other robots. I wanted mine to be mechanically
rugged, and to have an enclosed look. Early on, I began searching for
electrical enclosures as they are ideal for high strength and variety of
shapes and sizes. They tend to be expensive in retail stores, but can be
found cheap in surplus stores. My enclosure came from Ax-Man, as did the
gear motors, wheels, front castor, IR sensors, micro-switches, springs, as
well as a bunch of other parts. I accumulated the parts over several months
as I formed an idea of what could be done with the parts available, and
tried various sources for alternatives. I got the ultra-sonic transducers
from M.P. Jones (thanks for the tip, Bill!) I bought the microcontrollers
through my work.
- Operational description: As of this writing, I have not run the
robot autonomously yet, but the idea is that the machine will be able to
explore a safe space, and avoid most obstacles without touching them. Those
object which it can't see, it may bump into, then back off and find another
way around. Some obstacles, like over-hangs, stairs, ruts or bumps, etc.
are not accounted for and will therefore be a problem. I want the machine
to be able to maneuver the Science Museum class room, and not damage itself
or anything else. Anything beyond that will be great, but not expected.
- Future Enhancements/Plans:I am still thinking on what sounds it
will make. I have a speech recorder chip, the idea here is to select some
of its pre-recorded words and phrases to provide simple communication, I am
also looking at a full speech synthesizer, allowing a much larger
vocabulary. Maybe someday I can put in an RF link, for steering the machine
and putting it into different modes, also be able to manually control the
lights and sound for demonstration.
- Status: Mechanically, it is 90% complete, the circuits and software
are still in-process. I build a prototype motor drive, but found weaknesses
that must be fixed. The IR sensors I tested were not good, so I am starting
over on those. The ultra-sonics have yet to be built or proved. Finding
time to do everything is a problem, but playing with and learning the
technology is what it is all about!
- More Info: I hope to have a web site coming soon...