Go to Post Unlike robot design, in the clothing world there's no such thing as too much pocketing - Jaci [more]
Home
Go Back   Chief Delphi > Technical > Technical Discussion
CD-Media   CD-Spy  
portal register members calendar search Today's Posts Mark Forums Read FAQ rules

 
 
 
Thread Tools Rate Thread Display Modes
Prev Previous Post   Next Post Next
  #27   Spotlight this post!  
Unread 27-04-2004, 12:12
Rob Colatutto's Avatar
Rob Colatutto Rob Colatutto is offline
Roboticsrob
FTC #10092 (Green.Griffins;)
Team Role: Mentor
 
Join Date: Feb 2002
Rookie Year: 2001
Location: San Diego, CA
Posts: 849
Rob Colatutto is a splendid one to beholdRob Colatutto is a splendid one to beholdRob Colatutto is a splendid one to beholdRob Colatutto is a splendid one to beholdRob Colatutto is a splendid one to beholdRob Colatutto is a splendid one to beholdRob Colatutto is a splendid one to behold
Re: Four Wheel, all steering, non-omniwheel, ONE power/motor source drive

Quote:
Originally Posted by FizMan
Are you saying that:
3 motor gearbox + 3 motor gearbox +2xTransmission < 6 motor gearbox + 1xTransmission?
I would look at this question from an overall robot design standpoint... If you have one huge (relatively) gearbox in the center of your robot, thats going to limit you on your ability to integrate your mechanisms into the robot, espescially an arm with a wide degree of freedom. If you do the two seperate transmissions route, you leave the entire center of your robot free for whatever you see fit. If you look around, there are a lot of evolving 'drive module' designs that have the entire drive sections of the robot all compact in thier own self supporting 5" wide (sometimes even smaller) sections on the outside of the robot. Also something to care about, having that big gearbox in the middle of the robot could require you to raise anything else that would typically go down the center of your bot and drastically raise your CoG.


Quote:
Originally Posted by FizMan
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.
If you are using steel shafts, the weight adds up extremely quickly. A full robot lenght shaft would also need to be very supported into your robot, and to have one for each set of wheels, that is a whole lot of weight. Check into the bending moment on shafts that long, and then to have it be a powered drive shaft.... you get the idea. Having just 4x 5 inch non-powered wheel supporting shafts is a big advantage in the weight saving department.


Quote:
Originally Posted by FizMan
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.
Adding a shifter into a gearbox should probably not require many extra shafts than you would normally have. Just the one shifter shaft which you will need in a unified gearbox anyway. If you are adding a lot of extra, you may want to check your gearing layout. Having 2 individual shifting pistons doesn't mean you will use a lot of air. This year on our fall drive base and competition robot we used 2 individual 1/2" throw 3/4" bore pnuematics and were about to shift about 35 times conservatively. No onbaord compressor was ever required. Even if you had 2 1" throw pistons, are you really going to be shifting that much in a single match?


Quote:
Originally Posted by FizMan
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...
On top of just added weight, thats 7 motors minimum you are looking at into just your drive. You need to remember the wonderful rules of power distribution, and make sure you have acceptable motors for the rest of your mechanisms. The turning motor will need its own gearbox also and shafts/chain to make it to all 4 wheels. A reversing gear would require another extra shaft and ultimately, more weight. Wheel support is not something you should go lightly on. I know in 2002 some teams who lifted goals ended up paying for it in the long run when thier wheels bowed outward after a few competitions.
In all, do you think the added complexity and weight are worth it? Not to mention the array of extra parts that will need to be designed and fabricated.
__________________
Follow me on twitter @roboticsrob and my FTC team @griffins10092
 


Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Quatro 4 wheel drive ufa_mike Control System 2 15-04-2004 02:30
Quatro 4 wheel drive ufa_mike Control System 1 14-04-2004 21:45
need glp programing steering with a steering wheel Matchew Programming 2 10-02-2003 14:20
4 wheel steering/ Crab Huey_Da_X-cat Technical Discussion 3 11-02-2002 22:49
wheel drive Greg Needel Technical Discussion 3 29-01-2002 12:12


All times are GMT -5. The time now is 14:27.

The Chief Delphi Forums are sponsored by Innovation First International, Inc.


Powered by vBulletin® Version 3.6.4
Copyright ©2000 - 2017, Jelsoft Enterprises Ltd.
Copyright © Chief Delphi