one wheel drive

[Simon Strauss]

this is just an idea that i have and i haven't talked it over with my whole team yet but if one were to want to only have one wheel receiving power, would they benefit from having all four cims geared to that transmission. if so how would one go about doing that? i was considering that a third gearbox like last years could be bought then the other two placed into that in some manner, but since i don't have them in front of me at the moment could i get some insight on this matter.
thanks

[greencactus3]

techinically the ideal is to have power to all points touching the floor. so a 1wd robot that has only one wheel would be cool. a kind of 3d segwayish thing... but we've had plenty of threads like the ball robot thread...
OR. are you saying have like a steerable powered wheel and 2 or more non powered wheels? like a tricycle? unless you have a lot of weiht on that 1 wheel, it wont be pushing too much.. but it would handle just like a tricycle lol.
and 4 cims for 1 tire is a lot of power.... overkill i htink. you can get away with massivly grippy tires tho... personally i like my 4wds.

[Simon Strauss]

im not saying what i had in mind but how do you think that this(gearing all 4 cims) could be done, and would it help or just get in the way?

[sciencenerd]

As far as I can tell, a one-wheel drive would not be of any benefit. You get no power increase to the drivetrain, because you still have the same number of motors, they're just arranged differently.

Although there would be (small) weight savings from not having to run the chain to as many wheels, that is outweighed by the disadvantages. The main one I can see is you would have less traction, only one wheel would have to spin out for you to stop going anywhere, instead of two, or four, or six; etc.

EDIT: Removed a previous edit that was incorrect

[Greg Needel]

you can do it by using 1 large gear and meshing all 4 motors to it in a gearbox.

or you can do what i think you were describing and use 2 kit gearboxes and attach both to a common output shaft.

but i have the same thoughts about what your advantage is?

the main thing that i think needs to be considered is that there is a maximum effective torque that your robot can use. This is limited by the friction, contact with the floor and the max weight of your bot.

if you want to still pursue this i would be glad to help you design something to meet your needs, as i am alway interested in new ideas

[Tristan Lall]

To operate them together, just gear or chain them all together. (It's that simple.) You could do two kitbot transmissions chained to sprockets on each side of the wheel, for example.

Well, it's almost that simple. You can assume that they'll all spin at approximately the same speed, out of the box, certainly close enough for your purposes. Perhaps the only real pitfall is getting the polarity or PWM backward on some of the motors—you can probably guess the result.

Those considerations aside, you've already heard a few responses discouraging the idea. Let me expand on the reasons:

You have a ton of power at that one wheel; if, however, that wheel isn't in contact with the ground, you can't move.

Also, since the traction of that wheel is going to depend on the amount of weight acting on it, you want to support your robot entirely on driving wheels (if possible), so that you're not wasting any of the robot's weight. It's a waste, because your pushing ability is a function of the traction—so in essence, if you divide your weight among several contact points, and only one is powered, you're going to divide your pushing ability by a similar proportion.

Now, you've got to also steer somehow. Traditionally, robots steer by varying the speeds of their wheels—obviously you can't do this. You'd have to implement some other form of steering, like Ackerman (car) steering, or actuating brakes on the wheels located on the inside of the curved path that the robot follows (somewhat like a tank). Actually, the best method here is probably to design a large swerve module, mount everything inside of it, and put it in the middle of the robot. For various mechanical reasons, none of these are very practical.

Basically, compared to a 4WD, wide-tracked kit frame with kit transmissions, all of these 1WD ideas pale in comparison. I've heard that there's no such thing as a bad idea; well, whoever said it was wrong—this is a bad idea. But that's not to say that the thought process involved was a bad one; in fact, I commend you for thinking outside of the box, and putting serious consideration into the matter. But just this once, I'd urge you not to try to implement this on a competition robot, unless you take masochistic pleasure in dealing with your robot as it experiences the problems listed above.

[KenWittlief]

NYCpunk,

with all the people telling you this is a bad idea, I think you must be onto something that could be a robotics breakthrough.

When DK said he wanted to make a wheelchair for the disabled, that would balance on two wheels, that could go up and down stairs 'fly by wire', the most common response he got was "are you nuts?"

so I have to ask: one wheel drive? Are you nuts?

I hope you are

as crazy as Dean :^)

[Simon Strauss]

Thanks for all the suggestions and discouragements(they actually helped me realize some things) but the question i was asking though apparently unclear was will one profit from more than two motors geared together or not and if not how and what do you suggest to get the most power on this wheel? I already understood most of the cons of this idea and rest assured that i think i know what im doing (and if i don't our engineer should) and their are reasons for wanting one wheel drive other than to prove people wrong(which i will and you will hopefully see soon). however this is just an idea and its implementation relies on the type of game this year and other ideas we have in the works and if we don't end up using it ill try to get a copy of inventor from my team and create a concept design to show.

P.S. oh yeah kenwhittlief i am nuts

[sanddrag]

Originally Posted by nycpunk

there are reasons for wanting one wheel drive

Would you mind listing them? Because I sure couldn't come up with any.

I get the impression that you think that "harnessing" your power at one point will make the robot more powerful. This is simply not the case (darned physics ). In general terms, as long as all the motors are somehow connected to a wheel on the ground, it doesn't give you more power to have more or less wheels on the ground. Now, if you were considering having four motors driving instead of two, yes, that would give you more power. But if you wanted four motors driving two wheels as opposed to four motors driving four wheels, that wouldn't give you more power.

[Simon Strauss]

Originally Posted by sanddrag

I get the impression that you think that "harnessing" your power at one point will make the robot more powerful. This is simply not the case (darned physics ).

oh no not for power reasons, i was considering this for maneuverability/turning/wanting to be creative reasons (i don't want to say exacts to maintain a mystical essence) and was just wondering that if one were already set on this idea would more motors help

[KenWittlief]

the best way to answer you question is to point out: you can only use the motors that are supplied in the kit of parts

and every team gets the same kit, the same motors

if you could use all of them, and tie them to your drivetrain so they share the load, then you will have the maximum possible drivetrain power (HP) on your bot

and if you use half the motors, you will have half the possible power...

so, yes. The more motors you have in your drive train, the more power available, no matter how many wheels your bot has.

[Rickertsen2]

IHot team 1414 did this one year and one year only.