Subject:
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Project Questions
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Newsgroups:
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lugnet.robotics.handyboard
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Date:
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Sun, 9 Nov 1997 22:53:06 GMT
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Original-From:
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Abhay Saxena <ark3@mit.*nospam*edu>
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Viewed:
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1590 times
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Three of us are undertaking a project using the Handyboard as the control
system for a class at MIT. Our project, an autonomous blimp, has an unusual
set of constraints, but we're hoping that your collective experience might
be able to help us nonetheless. Our primary constraint is weight, as the
blimp is able to lift only about seven ounces of weight beyond its
propulsion system, although, if necessary, we will be able to attach
additional balloons to generate more lift at the expense of a major loss of
aerodynamics. Can anyone tell me how much a handyboard weighs (with its
power source) in grams or tenths of ounces?
In order to allow the blimp to roam autonomously, we intend to use two
pivotable ranging sensors to let the Handyboard generate a representation
of its surroundings. That, along with dead reckoning, will (hopefully)
allow the blimp to fly around on its own. We plan to mount the sensors on
tiny servos that will allow the Handyboard to angle the sensors as
appropriate for the situation. The blimp's propulsion system requires the
use of a third servo and two drive motors. Therefore, the Handyboard will
be driving two motors, three servos, and two ranging sensors. Any
suggestions on how to make that workable? Driving three servos seems to be
the most problematic aspect of this.
The drive motors each require about an amp at five volts, but we've been
told that we can drive them at 9.6 volts at 600 mA without any problems as
long the voltage regulator is "beefy" enough to handle the motors'
kickback. As we're not familiar with either the motors or the Handyboard,
can anyone suggest how we might investigate whether the "beefiness"
aspect of problem is covered once we obtain them?
We're currently considering the Polaroid ultrasonic ranging sensors
mentioned on the Handyboard page, but they have the disadvantage of
having a small acceptance angle, meaning that essentially it will only
give readings when fired directly at a wall (not at an angle to the
wall). Has anyone had any experience with the Polaroid sensors or any
other ranging sensors?
Finally, we have the problem of actually obtaining a Handyboard. As
neither the class's budget nor our own is very large, we were hoping
to get some sort of educational discount on the purchase of a
Handyboard. Can anyone recommend a Handyboard distributor who might
offer us a good price? Ideal, of course, would be for someone to
donate or loan us a board.
Here is a quick summary of our questions:
1. How much does the handyboard + power source weigh (grams/ounces)?
2. Can we drive two motors, three servos, and two ranging sensors?
3. How do we test whether the Handyboard voltage regulator is "beefy"
enough to handle the motors?
4. How well do the Polaroid sensors work? Can you recommend anything
with a better acceptance angle?
5. How can we obtain a Handyboard inexpensively or get one donated or
loaned to us for our school project?
Thanks very much for your help.
- Abhay
---------------------------------------------------------------------
Abhay Saxena Ashdown House 312D . __ You can lead a horse
ark3@mit.edu 305 Memorial Drive /|(_ to water, but pastrami
(617)225-9734 Cambridge, MA 02139 (____) sandwiches don't float.
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