Re: Four Wheel, all steering, non-omniwheel, ONE power/motor source drive
 

Now that i thinkabout it 4 reverse gears are not needed in my preious design if the wheel turning horizontal _ chains are run off of 2 spockets and two globes or windows or something. Instead of the M more of a X

This way you have no reverse, except for on all ofthe wheels at the same time, but you can turn the front wheels 90 degrees to the left and the back 90 degrees to the right. It wil created tank type steering and turn your front into the side, until the turn is over and the driver staightens out the wheels to dive again. There is also steering like a car, but better, cause you can turn the back wheels too, which is an option now sometime on the newer models :D .

Re: Four Wheel, all steering, non-omniwheel, ONE power/motor source drive
 

Would someone mind explaining to me how the power would be transfered to the wheels in a system like the ones shown here. I've been looking at a lot of the pics...and am obviously missing something, because I don't see anyway the power from the motors is getting to the wheels.

Re: Four Wheel, all steering, non-omniwheel, ONE power/motor source drive
 

This is just my two cents:

I would suggest staying away from the Reverse gear unless you want things to get very mechanically complex. Also, by using a reverse gear instead of changing motor direction, you cannot make point-turns, you can only counter-rotate. Think about it: Your wheels in reverse go as fast as your wheels in forward, and as far as I can understand, there would be no way to stop only one side of your bot. Personally, I would go with separate drives, but thats just my opinion.

Also, Henry_222's idea sounds cool, but:
1 drive motor + 4 module rotation motors = 5 total OR....
4 drive motors + 1 module rotation = 5 total <--- I'd go for that, more power to the floor, even if more complex.

Re: Four Wheel, all steering, non-omniwheel, ONE power/motor source drive
 

Also..if your using the chips in the drive....there isn't a large speed difference...so for reversing...I doubt you would ever notice a difference in just going backwards.

Re: Four Wheel, all steering, non-omniwheel, ONE power/motor source drive
 

Fizman- Not that it matters too much, but your wheels should only have to rotate 90 degrees to swerve if you run ur drive motor(s) forward and reverse

Rod- Could you explain how power is transferred from the motor to the wheels on your design, and how the wheels change direction/speed?

Re: Four Wheel, all steering, non-omniwheel, ONE power/motor source drive
 

I would suggest mounting your 3 speed transmissions in the center and then have miter gears coming off that connect to the wheel modules...we were thinking of doing this but didn't have the recouses to pull it off

Re: Four Wheel, all steering, non-omniwheel, ONE power/motor source drive
 

I'm curious if you could run into a situation where you have too much power. There has to be a point where you just have so much power that you can't transfer it to the carpet because the wheels are slipping. Is there any way of calculating this?

Re: Four Wheel, all steering, non-omniwheel, ONE power/motor source drive
 

The senario you described wouldn't be a problem of too much power, it would be a problem of too little traction.

Re: Four Wheel, all steering, non-omniwheel, ONE power/motor source drive
 

Well the point I was trying to make is... how much power is so much that it doesn't matter? Simply because you will run into the traction problem.

Re: Four Wheel, all steering, non-omniwheel, ONE power/motor source drive
 

oh, the old coaxial crab drive. a potentialaly shiftable omni drive desing sporting dashing manuverabilty

however there inavoidabaly heavy, complex. heavy, inefficent, batery hungary, recorce-eating things witch through the process of desinging my oun became Painfully apparent.

its still a wikid cool drivetrain tho

Re: Four Wheel, all steering, non-omniwheel, ONE power/motor source drive
 

Not ONE motor, one gearbox. Many motors potentialy. It is all in the application.

I like the ideas....but....
I see this whole venture of one power source to complicated and heavy to deal with. There are many other options.

Also,
I have only ever "peeled out" or skidded wheels on carpet once with a bot. It was a basic bottom chasis and had 6" wheels and a prototype 3 speed on the fly tranny. The wheels are the ones from the kit, Skyways I think. I flew around in 3 and slammed into 1. SKIDDDDDDDDD. And I started in 3, full stick. SKIDDDDDDDD, ZOOM. If the proper wheels are in the application, there can never be too much power. HE HE HE. :D


Ching Ching, thats my 2. On a lot of stuff.
-Henry

Re: Four Wheel, all steering, non-omniwheel, ONE power/motor source drive
 

Sure there can. When you start ripping up carpet, you have to much power and traction.

This does happen, and teams do get disqualified for it.

-Andy A.

Re: Four Wheel, all steering, non-omniwheel, ONE power/motor source drive
 

I don't know; I see the venture of one power source (while complicated) could potentially be lighter than multiple ones. I mean; even if you have to build a monster gearbox, it'd still only have to be twice the size (maybe less if you're good at compaction) than having two smaller gear boxes. Have to mount 2 motors in a gearbox? Have a gear box X size. Have to mount 4 motors in a gearbox? Have a gear box 2X size. Am I right? So the weight evens out there.

But then you can have a single transmission for the whole thing; 1/2 the pneumatics, 1/2 the mounting, 1/2 the gearing.

Re: Four Wheel, all steering, non-omniwheel, ONE power/motor source drive
 

With the centralized design you still have the weight of the motors. If you want to add more the a couple you have to have all the gearing to join them. If you want it to shift you can save some weight on only one but you would make up some of that on the amount of chain. Pneumatics don't weigh a lot past the first cylinder. Several of the gearshifting design use 3/4" cyclinder at a very short stroke which are very light.

What you are wanting to do is heavy by nature. With the right design and materials a centralized gearbox may be lighter. This is a tough one to call either way though. The xbox is a fairly good example of this but they said they weighed ninety pounds without shifting. And the only used to motors. More than this would require additional gearing and the gear shifting mechanism would have to be added. In this case you are looking at at around another 20+ pounds which will leave you with a 20 lb arm at most. Weight is a hard constraint to deal with. I think we would see a lot more drivetrains like you envision if we could weight 20 to 30 more pounds.

Re: Four Wheel, all steering, non-omniwheel, ONE power/motor source drive
 

Are you saying that:

3 motor gearbox + 3 motor gearbox +2xTransmission < 6 motor gearbox + 1xTransmission?

A central gearbox would indeed require chain and/or a shaft extending out to the other wheels, but I don't see that taking up that much extra weight. Besides; other drive systems would require the same thing to transfer the power out to the wheels.

And with the shifting, it's not just the pneumatics; it's the extra mounting, gearing, maybe another shaft. Plus if you can reduce the amount of pneumatics required to fire to shift; we might be able to ditch the need to include the air compressor.

When I compare something like this to a traditional tank drive system; I see the only extra weight coming in to support the one extra motor to turn all the wheels, and maybe the little bit more with the wheel mounts. And then the reversing gear; which would probably weight the same amount or less than the second transmission. Or perhaps better yet; maybe it can be implemented along with the transmission somehow...