Servo - May 2008

higher end requirement still under discussion would be for the bot to grasp an unconscious person and pull them out of an extremely dangerous situation, to a spot where rescue workers could intervene.

Being a near-farm boy myself, (we lived in town, but it had 800 people and only one hardware store), I thought about what a rural farm shop might have available to build something like this. Out of that came some general design requirements:

End of Bot Dimensions.

Frame Dimensions.

hardware, home improvement, or farm supply store. Rest easily ordered on-line.

5) Power by common motorcycle, ATV, jet ski, snowmobile sealed lead acid battery; 120 VAC battery charger on board.

• Four Victor 883 ESCs

• Two Hawker/generic SLA batteries

• Steel frame

• Cheap, simple, and robust

1) Must be able to be built in a medium sized farm or school shop, or a welding shop by generally handy people.

2) Must be able to function in an explosive atmosphere. This means the electrical devices must be fully enclosed.

3) Any functions done in the field (on/off switch, changing payloads, carry bars) can be done in full turnout gear with breathing mask (gloves, full face mask, coat, boots, helmet). Radio can be operated with bare hands.

4) Most parts available at a chain

6) Service and major component replacement in firehouse using only common hand tools.

7) One failure tolerant for critical functions (Multiple motors each side? Parallel ESCs?).

8) Indicators provided (LEDs) to assist in troubleshooting and operational verification. Critical indicators must be visible through binoculars from several angles.

After some preliminary back and forth brainstorming, Chewy from Team Tiki popped in with a rock solid basic parts list:

• Four NPC T- 64 gearmotors

Within 15 minutes of seeing this list, I was on The Robot MarketPlace ( www.robotmarket place.com) — my favorite vapor bot “pick list” site. I recognized that buying new might not be possible, given the limited resources of a rural fire department, but it seemed like a good starting point. Out of that exercise came the following design “concept.” These are ugly as original sin and twice as smelly, but remember we’re being honest here. We’ve all done it, even if we don’t show them in public. So here, using PAD software (Powerpoint Aided Design) is what I came up with. (I added two batteries, a master switch, hubs and wheels, and radio system to Chewy’s basic list). I then