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-   -   Crazy Drive Train Ideas (http://www.chiefdelphi.com/forums/showthread.php?t=86059)

kgzak 15-09-2010 16:48

Re: Crazy Drive Train Ideas
 
Mecanum swerve :yikes:

buildmaster5000 15-09-2010 17:40

Re: Crazy Drive Train Ideas
 
Quote:

Originally Posted by kgzak (Post 974244)
Mecanum swerve :yikes:

That would defeat the purpose of swerve: low traction omni drive is simply mecanum. The whole point of swerve is to have high traction omni drive

kgzak 15-09-2010 22:51

Re: Crazy Drive Train Ideas
 
Quote:

Originally Posted by buildmaster5000 (Post 974255)
That would defeat the purpose of swerve: low traction omni drive is simply mecanum. The whole point of swerve is to have high traction omni drive

we were talking about it for a test platform. that way programers have a robot that you can run a few different drivetrains without having to change anything. It kinda became a joke throughout the season because we didn't know whether we wanted swerve or mecanum. I realize that it is on of the most pointless designs.

Mountain Man 16-09-2010 00:27

Re: Crazy Drive Train Ideas
 
See below.

http://www.chiefdelphi.com/forums/sh...threadid=86862

Mageofdancingdr 16-09-2010 02:22

Re: Crazy Drive Train Ideas
 
Quote:

Originally Posted by JamesCH95 (Post 974240)
^ exactly like that EricH said, the total integral work possible (not including mechanical inefficiencies) using the compressor for a whole match is 10.1kJ, whereas running 1 cim motor at full power for the whole match is 47.3kJ. So one CIM motor is nearly 5 times as powerful, and with proper gearing can deliver the same pushing force as pneumatics would.

What this says is that you need a compressor powered by several CIM motors :p

what if you create a shifting mechanism between pneumatics and CINs, so you can push with pneumatics engaged and drive with the CIM motors?

also, when I was thinking of power, I was thinking of the power during the time before the tanks ran out, which I think would be more powerful than the CIMs during the same time period (how would I do the math to find out though, where is the power rating for a cylinder?)

Ether 16-09-2010 08:17

Re: Crazy Drive Train Ideas
 
Quote:

Originally Posted by Mageofdancingdr (Post 974290)
I was thinking of the power during the time before the tanks ran out, which I think would be more powerful than the CIMs during the same time period (how would I do the math to find out though, where is the power rating for a cylinder?)

The power you can get from pneumatics on FRC is limited not by the cylinder, but by the solenoid ⅛” NPT port diameter and maximum Cv of 0.32

You can use solenoids in parallel to mitigate this somewhat, but other fittings and line losses limit what you can achieve.

A CIM has a maximum power of 337 watts, but this can be sustained only briefly, not the entire match.



JamesCH95 16-09-2010 09:19

Re: Crazy Drive Train Ideas
 
Quote:

Originally Posted by Mageofdancingdr (Post 974290)
what if you create a shifting mechanism between pneumatics and CINs, so you can push with pneumatics engaged and drive with the CIM motors?

also, when I was thinking of power, I was thinking of the power during the time before the tanks ran out, which I think would be more powerful than the CIMs during the same time period (how would I do the math to find out though, where is the power rating for a cylinder?)

It is possible to do what you've described, but it is probably more cost and weight effective to use a shifter transmission because you will be traction limited.

And... what is this? A student who wants to know how to the math?! I'm confused and terrified right now :D more on this later...

Quote:

Originally Posted by Ether (Post 974294)
The power you can get from pneumatics on FRC is limited not by the cylinder, but by the solenoid ⅛” NPT port diameter and maximum Cv of 0.32

You can use solenoids in parallel to mitigate this somewhat, but other fittings and line losses limit what you can achieve.

A CIM has a maximum power of 337 watts, but this can be sustained only briefly, not the entire match.


What Ether said, though IIRC it's the internal valve diameter that severely limits flow through a solenoid, and I can't remember the dimensions off-hand. And yes, a CIM cannot be run full-power for an entire match (probably not more than once, anyway), though 4 Cims could likely be run at an average of 1/4 power (maybe more?) for a whole match. This would be an interesting experiment.

Back to the math...

I assume you are referring to using pneumatics in a reciprocating-piston setup, in which case you can calculate a theoretical power output using ideal Otto cycle calculations, where your volume values are computed by geometry, and your pressure values are determined from approximate flow rates through the supplying solenoid(s).

Edit: it won't be exactly like an Otto-cycle calculation, but it will be close, you'll be integrating work done in a PV chart.

JesseK 16-09-2010 10:53

Re: Crazy Drive Train Ideas
 
The pneumatic cyllinder feasibility problem appeared simpler to me when I thought about it a few months ago. Simply add it in as a "turbo boost" to an existing drive train via a 1-way clutch or paulet system. Linking the two rear drive train axles together with 1 shaft (or 2 shafts + differential) would easily allow for this functionality.

Once implemented, we can analyze the weight: it's about ~15lbs extra, just for a brief turbo boost once or twice in a match. YMMV, but it wasn't worth it for me to investigate further.

Jared Russell 16-09-2010 11:15

Re: Crazy Drive Train Ideas
 
If you're hung up on the idea of a pneumatic drive (store energy, then expel it all in one forceful lunge forward), you could accomplish the same thing by using a far more efficient motor, like a CIM, to compress a spring or gas spring (like many kickers did this year).

Trent B 16-09-2010 11:23

Re: Crazy Drive Train Ideas
 
Quote:

Originally Posted by JamesCH95 (Post 974216)
Hehe, I suppose it is a little semantic, but there is a lot to be said for using precise and correct language, especially in the field of engineering.

I know the correct usage of power, the problem is so many people don't so for the average person it seems to have a tendency to have qualities of semantics. Gotta love common english language and its distortion of terms to mean other things.

JamesCH95 16-09-2010 11:34

Re: Crazy Drive Train Ideas
 
Quote:

Originally Posted by Trent B (Post 974311)
I know the correct usage of power, the problem is so many people don't so for the average person it seems to have a tendency to have qualities of semantics. Gotta love common english language and its distortion of terms to mean other things.

If you know how to use it properly then do not perpetuate its misuse! That is how common English screws things up.

Trent B 16-09-2010 11:52

Re: Crazy Drive Train Ideas
 
I use it correctly, 2 years of physics does that to someone :D

There are also always the crazy drivetrains where CIMs and Fisher Price motors are all connected together through a gearbox using planetary gearboxes or some other method to constrain the FP output to the same as a CIMs output RPM. As far as I can tell that would probably be the most powerful setup you could get. Though you would have to rely on Densos, Pneumatics and Globes (if they brought them back) for other components of your drive train.

Mageofdancingdr 17-09-2010 09:18

Re: Crazy Drive Train Ideas
 
Quote:

Originally Posted by JesseK (Post 974307)
The pneumatic cyllinder feasibility problem appeared simpler to me when I thought about it a few months ago. Simply add it in as a "turbo boost" to an existing drive train via a 1-way clutch or paulet system. Linking the two rear drive train axles together with 1 shaft (or 2 shafts + differential) would easily allow for this functionality.

Once implemented, we can analyze the weight: it's about ~15lbs extra, just for a brief turbo boost once or twice in a match. YMMV, but it wasn't worth it for me to investigate further.

well, this is what preliminary discussions (me and my friends talking at lunch) usually boiled down to, so if it doesn't seem feasible it's okay being dropped. Plus, I'm the programmer, so I'll just make up the innovative edge on our robot with sensors and functions.

Ether 17-09-2010 09:33

Re: Crazy Drive Train Ideas
 
Quote:

Originally Posted by Mageofdancingdr (Post 974427)
3.1415926535897932384626433832

3.1415926535897932384626433833 :)




JesseK 17-09-2010 09:44

Re: Crazy Drive Train Ideas
 
Understanding it's still a whacky thought for potentially great innovation (weight aside), the process of implementing it is invaluable. It's probably best done in the offseason though so your competitions have less chance for failure.

Another idea to link a 'turbo boost' to an existing drive train would be feasible if the drive train implemented a car-style setup with a differential that is driven by a hybrid planetary gearbox. By 'hybrid' I mean that there is 1 output and 2 inputs to the planetary gearbox, much like what is seen in hybrid cars.

This would eliminate the need for a shifting transmission since the 'turbo' gives the extra power. It may also free up CIMs for use in other systems because an alternative power source is available for the drive train. Depending on the team, that may be worth it even during competition season.


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