Go to Post If said device costs 10x more to manufacture than a simpler solution integrating COTS parts, and only performs 10% better, that's poor engineering. - Cory [more]
Home
Go Back   Chief Delphi > FIRST > Robot Showcase
CD-Media   CD-Spy  
portal register members calendar search Today's Posts Mark Forums Read FAQ rules

 
Closed Thread
Thread Tools Rate Thread Display Modes
  #16   Spotlight this post!  
Unread 07-09-2004, 16:45
Andy Baker's Avatar Woodie Flowers Award
Andy Baker Andy Baker is offline
President, AndyMark, Inc.
FRC #3940 (CyberTooth)
Team Role: Engineer
 
Join Date: May 2001
Rookie Year: 1998
Location: Kokomo, Indiana
Posts: 3,422
Andy Baker has a reputation beyond reputeAndy Baker has a reputation beyond reputeAndy Baker has a reputation beyond reputeAndy Baker has a reputation beyond reputeAndy Baker has a reputation beyond reputeAndy Baker has a reputation beyond reputeAndy Baker has a reputation beyond reputeAndy Baker has a reputation beyond reputeAndy Baker has a reputation beyond reputeAndy Baker has a reputation beyond reputeAndy Baker has a reputation beyond repute
Send a message via AIM to Andy Baker
Re: pic: Iso view

Quote:
Originally Posted by JVN
Anyone else wanna confirm 85%?

JV
A few years ago, I was using 60% for what I called "working speed" (motor rpms at robot's top speed). The past few years, as our efficiencies have gotten better, this percentage of the free speed has gone up. Last year, we used 75%, I think.

I don't put too much faith in that number, though. It just gets us in the ballpark with regard to ratios, speed, and sizing. Our final number might have been 5% higher or lower, but it is about right.

John, you must have a very light robot or a very efficient drivetrain if you are running at 85% of your free speed.

Andy B.
  #17   Spotlight this post!  
Unread 07-09-2004, 16:53
Max Lobovsky's Avatar
Max Lobovsky Max Lobovsky is offline
Fold em oval!
FRC #1257 (Parallel Universe)
Team Role: College Student
 
Join Date: Jan 2004
Rookie Year: 2004
Location: Scotch Plains, NJ
Posts: 1,026
Max Lobovsky has a brilliant futureMax Lobovsky has a brilliant futureMax Lobovsky has a brilliant futureMax Lobovsky has a brilliant futureMax Lobovsky has a brilliant futureMax Lobovsky has a brilliant futureMax Lobovsky has a brilliant futureMax Lobovsky has a brilliant futureMax Lobovsky has a brilliant futureMax Lobovsky has a brilliant futureMax Lobovsky has a brilliant future
Send a message via AIM to Max Lobovsky
Re: pic: Iso view

Quote:
Originally Posted by Andy Baker
A few years ago, I was using 60% for what I called "working speed" (motor rpms at robot's top speed). The past few years, as our efficiencies have gotten better, this percentage of the free speed has gone up. Last year, we used 75%, I think.

I don't put too much faith in that number, though. It just gets us in the ballpark with regard to ratios, speed, and sizing. Our final number might have been 5% higher or lower, but it is about right.

John, you must have a very light robot or a very efficient drivetrain if you are running at 85% of your free speed.

Andy B.
Andy, I assume you are talking about a dual motor (2 CIM and 2 Drill) drivetrain. The percentage is obviously significantly lower when you have half the maximum power. This question might also explain the discrepancy between John's and your numbers.
__________________
Learn, edit, inspire: The FIRSTwiki.
Team 1257


2005 NYC Regional - 2nd seed, Xerox Creativity Award, Autodesk Visualization Award
2005 Chesapeake Regional - Engineering Inspiration Award
2004 Chesapeake Regional - Rookie Inspiration award
2004 NJ Regional - Team Spirit Award
  #18   Spotlight this post!  
Unread 07-09-2004, 17:07
Unsung FIRST Hero
JVN JVN is offline
@JohnVNeun
AKA: John Vielkind-Neun
FRC #0148 (Robowranglers)
Team Role: Engineer
 
Join Date: May 2001
Rookie Year: 2000
Location: Greenville, Tx
Posts: 3,159
JVN has a reputation beyond reputeJVN has a reputation beyond reputeJVN has a reputation beyond reputeJVN has a reputation beyond reputeJVN has a reputation beyond reputeJVN has a reputation beyond reputeJVN has a reputation beyond reputeJVN has a reputation beyond reputeJVN has a reputation beyond reputeJVN has a reputation beyond reputeJVN has a reputation beyond repute
Re: pic: Iso view

Quote:
Originally Posted by Andy Baker
John, you must have a very light robot or a very efficient drivetrain if you are running at 85% of your free speed.

Andy B.
Or... maybe I'm just wrong.
Thanks for sharing, Andy.

You heard it here first, folks. 70% is where it's at.

John
__________________
In the interest of full disclosure: I work for VEX Robotics a subsidiary of Innovation First International (IFI) Crown Supplier & Proud Supporter of FIRST
  #19   Spotlight this post!  
Unread 07-09-2004, 17:22
Paul Copioli's Avatar Unsung FIRST Hero Woodie Flowers Award
Paul Copioli Paul Copioli is offline
President, VEX Robotics, Inc.
FRC #3310 (Black Hawk Robotics)
Team Role: Engineer
 
Join Date: Jun 2001
Rookie Year: 2000
Location: Rockwall, TX
Posts: 1,392
Paul Copioli has a reputation beyond reputePaul Copioli has a reputation beyond reputePaul Copioli has a reputation beyond reputePaul Copioli has a reputation beyond reputePaul Copioli has a reputation beyond reputePaul Copioli has a reputation beyond reputePaul Copioli has a reputation beyond reputePaul Copioli has a reputation beyond reputePaul Copioli has a reputation beyond reputePaul Copioli has a reputation beyond reputePaul Copioli has a reputation beyond repute
Re: pic: Iso view

Or you can measure the actual resistance force and use that to find your no load running torque to find the actual speed you are running at. John, you will find that you are probably closer to 80-85%.
  #20   Spotlight this post!  
Unread 07-09-2004, 17:38
Andy Baker's Avatar Woodie Flowers Award
Andy Baker Andy Baker is offline
President, AndyMark, Inc.
FRC #3940 (CyberTooth)
Team Role: Engineer
 
Join Date: May 2001
Rookie Year: 1998
Location: Kokomo, Indiana
Posts: 3,422
Andy Baker has a reputation beyond reputeAndy Baker has a reputation beyond reputeAndy Baker has a reputation beyond reputeAndy Baker has a reputation beyond reputeAndy Baker has a reputation beyond reputeAndy Baker has a reputation beyond reputeAndy Baker has a reputation beyond reputeAndy Baker has a reputation beyond reputeAndy Baker has a reputation beyond reputeAndy Baker has a reputation beyond reputeAndy Baker has a reputation beyond repute
Send a message via AIM to Andy Baker
Re: pic: Iso view

Quote:
Originally Posted by JVN
Or... maybe I'm just wrong.
Thanks for sharing, Andy.

You heard it here first, folks. 70% is where it's at.

John
OK, I need to clarify my background. In '99, '01, '02, and '03, we designed treaded drive systems. These systems had much more drag and lower efficiency than wheeled systems. In '04, we did a wheeled system. I *think* that 75% was a good number for us to use, but I may be wrong. We did not do any after-the-fact testing to verify this number.

Also, Max has a good point. We used CIM motors and FP motors for our '04 wheeled drive base, so the CIM motor was doing the majority of the work on the system. Since we did not have two balanced motors on the drive system, this may be the reason that our "working speed" % number was lower.

If we used 2 equally powered motors, I can see this number jump from 75% to 80 or 85%.

Andy B.
Closed Thread


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
pic: 217 Robot ISO view CD47-Bot Robot Showcase 8 01-03-2004 13:09
pic: 710 2004 side view of drive train CD47-Bot Robot Showcase 6 16-02-2004 19:43
pic: Right Side view CD47-Bot Robot Showcase 2 03-03-2003 15:26
pic: 141's Robot stacking side view CD47-Bot Robot Showcase 7 28-02-2003 12:16
pic: 857 rear view programming CD47-Bot Robot Showcase 1 25-02-2003 22:24


All times are GMT -5. The time now is 03:01.

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