How can we drive on this new floor?

[Creator Mat]

What if we did a air boat type drive train. where we take a floor fan gut the motor and replace it with a shaft and a belt drive to a few CIMS (or direct connect). Then our wheels would be attached to casters. To steer we would have directional flaps powered by servos on the back.

+: could defend the trailer if powerful enough, takes away some traction problem.

-: stopping could be an issue (but thats what brakes are for), and the power of the fan could not be powerful enough to move the robot.

[adaptingthought]

Im with the fan idea for propulsion. Not sure if it's legal though

[cj.reeves]

You want as little interaction between the wheels and floor as possible, although the fan is risky there are other ways to move your robot without interaction with the sourounding medium. As we all know a tank steer or skid steer is out of the question a 40lb flywheel spinning at a couple thosand rpm spun by the windsheild wiper motor on the horizontal axis should spin the robot on a dime just how NASA stabalizes their satelites in space it works on SW 2008

[Creator Mat]

Originally Posted by adaptingthought

Im with the fan idea for propulsion. Not sure if it's legal though

How would the fan not be legal? It could stay within size constraints, you would have to enclose it but that wouldn't be that hard if you use a premade fan, and you still use the wheels on the ground.

[Creator Mat]

Originally Posted by cj.reeves

You want as little interaction between the wheels and floor as possible, although the fan is risky there are other ways to move your robot without interaction with the sourounding medium. As we all know a tank steer or skid steer is out of the question a 40lb flywheel spinning at a couple thosand rpm spun by the windsheild wiper motor on the horizontal axis should spin the robot on a dime just how NASA stabalizes their satelites in space it works on SW 2008

But how would you move across the field? the flywheel would make you spin but the trailer would mess that up, plus to put in a fly wheel would take up a lot of space.

[Dan2081]

Can the battery power a large fan for 2:15' straight???

[adaptingthought]

someone found a fan thats legal by FIRST regulations

http://www.modelflight.com.au/rc_mod..._micro_fan.htm

i dont know the calculations to find out how long the battery could power it though

[Creator Mat]

don't know might not but you only use the fan as the major draw of power off the battery i don't see why not. think about it using 4 CIMS to move a robot on wheels with high friction/wieght and a pnuematic system drained most of our battery last year. but if we where to use only the fan it would be 1-4 CIMs moving at most a 5 pound fan (im being very heavy) in a circle constantly, in my opion would not drain the battery that much.

[Creator Mat]

Originally Posted by adaptingthought

someone found a fan thats legal by FIRST regulations

http://www.modelflight.com.au/rc_mod..._micro_fan.htm

i dont know the calculations to find out how long the battery could power it though

im not using any rules as backing here but from what i know as long as the fan is enclosed (no sharp/dangous appendages) and you use CIMs to power it not the motor that came with the fan (illegal motor) the fan would be legal

[GregW11]

Originally Posted by johnr

Does this make any sense? Six wheeled bot. Four corner wheels driving forward and two side centered wheels driving backward as needed. Or, one wheel dead center of bot that would spin oppisite as needed. Then hand the whole thing over to programers. They can make it work.

I would guess this is roughly the setup you had in mind with wheels:

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(with possibly more series of sideways and forward-facing wheels)
Vertical wheels are forward facing, horizontal are sideways facing, in case people don't know.

And that wouldn't exactly be difficult to program, but the operators would have to have incredible coordination, since assuming you're driving in tank mode it would require three joysticks (two for each set of wheels, plus one more to operate the side wheels.) Add more motors if you want additional sets of wheels, unless you can put three wheels on one motor...

Either that or have the side wheels spin in conjunction to the outputs of the joysticks (i.e. if left is spinning full forward and right is spinning full backward, the wheels will turn in the direction that will provide the most traction. I'd have to run a simulation to determine exactly which would be the best way, whether you want more turning force, causing the trailer to possibly fishtail, or less to stabilize it.)
Again, not apparently difficult to program.

edit: (with random concerns I think of)
The only thing I could see right now is collisions of of the chains (if they're used to provide the moving force for the wheels) from the forward/sideways wheels. Seems it could be remedied by using varying radii with the grabbers on the wheels (spaced the name of them) that move the chain.

[PowerOfKings]

Originally Posted by vivek16

Look, all the ideas with fans:

Why not take your 200 pounds of force going downwards, point that to a side, and use it as a means of propulsion? It would certainly be a lot more efficient than using the force to increase the traction (it will still be low traction).

-Vivek

The 200 pounds of force comes from the fact that it is a vacuum creating pressure underneath the robot so in a 10x10 area with 1 psi (pound per square inch) you would have 100 pounds of force. You would not have nearly the same force from simply the fan on the side.

However we calculated that it would only take 7 pounds of force applied from the side to start a robot moving sliding sooo...

[Cyberphil]

Did anyone else see the size of that fan? Do you really think that would be worth buying 30 of those for a little bit more propulsion? Personally, I think its a waste of time, and how can we have tank treads if the rules state: "The ROVER WHEELS must be used in a “normal” orientation (i.e. with the tread of the wheel in contact with the ground, with the axis of rotation parallel to the ground and penetrating the wheel hub). No other forms of traction devices (wheels, tracks, legs, or other devices intended to provide traction) are permitted."

[JagWire]

Originally Posted by adaptingthought

someone found a fan thats legal by FIRST regulations

http://www.modelflight.com.au/rc_mod..._micro_fan.htm

i dont know the calculations to find out how long the battery could power it though

Unless I'm off my rocker, 200g of thrust means a little less than a half-pound of thrust? You'd need something like 14 of them to be roughly equivalent to the amount of force produced by frictional interaction from wheels.

I made that approximation based off a calculation of maximum frictional force by multiplying the weight (120lb.) by the *kinetic* coefficient of friction (.05 from the first manual), yielding a maximum force of 6lbs. to accelerate the robot. So, that's a lot of fans. Running all of them at their maximum of around 300 Watts each, that accounts for 4200 watts, and, I could be wrong, but I believe that would mean it would discharge one of the 12v 18Ah batteries in around 3 minutes.

So, that particular fan sounds pretty in-efficient to me. I would suggest looking for one with a much larger prop. Larger, slow moving props tend to have a higher efficiency (not to mention they tend to be a little safer). A larger prop would also mean more thrust, and fewer fans. Knock the number of fans needed down to 4 or so, and it would be manageable I think.

I'm still intrigued by the possibility of a fan-propelled bot. I think it would be quite spectacular to watch in action.

*EDIT*
This is all completely without regard to the legality of the fan and motor, merely assessing the viability of the particular product.

[JagWire]

Originally Posted by Cyberphil

Did anyone else see the size of that fan? Do you really think that would be worth buying 30 of those for a little bit more propulsion? Personally, I think its a waste of time, and how can we have tank treads if the rules state: "The ROVER WHEELS must be used in a “normal” orientation (i.e. with the tread of the wheel in contact with the ground, with the axis of rotation parallel to the ground and penetrating the wheel hub). No other forms of traction devices (wheels, tracks, legs, or other devices intended to provide traction) are permitted."

I think they were referring to what is called "tank drive" which you can think of like driving a bulldozer, only without the tracks, just the wheels. The wheels on one side would operate together independently from the other side.

[chuckmerja]

Interesting that game team used "traction" with respect to wheels etc, and didn't use the word "propulsion", thus maybe leaving a fan solution open to possibility. Hmm