My camera can always tell when you're near.
Home
Go Back   Chief Delphi > Technical > Motors
CD-Media   CD-Spy  
portal register members calendar search Today's Posts Mark Forums Read FAQ rules

 
Reply
Thread Tools Rate Thread Display Modes
  #1   Spotlight this post!  
Unread Today, 19:32
bc414 bc414 is online now
Registered User
FRC #1403
 
Join Date: Feb 2017
Location: New Jersey
Posts: 4
bc414 is an unknown quantity at this point
CIMs, Weight, and Max Speed

Will a 2 CIM per side drive train have a reduction in maximum speed when going from a 60 pound load to a 120 pound load? I am hoping to program autonomous using just the drive train and the electrical board while the rest of the robot is being built, but the algorithms I am using are dependent on the maximum speed of the robot.
Reply With Quote
  #2   Spotlight this post!  
Unread Today, 19:39
DaveL DaveL is offline
Registered User
FRC #2976
 
Join Date: Jan 2013
Location: WA
Posts: 176
DaveL is a jewel in the roughDaveL is a jewel in the roughDaveL is a jewel in the roughDaveL is a jewel in the rough
Re: CIMs, Weight, and Max Speed

I would expect a slight decrease in speed due to increased friction on carpet from the extra weight. This is assuming traction wheels. I would guess that Mecanum wheels would have a larger decrease in top speed.

However i would expect the biggest difference to be in acceleration.

Dave
Reply With Quote
  #3   Spotlight this post!  
Unread Today, 19:42
Lil' Lavery Lil' Lavery is offline
TSIMFD
AKA: Sean Lavery
FRC #1712 (DAWGMA)
Team Role: Mentor
 
Join Date: Nov 2003
Rookie Year: 2003
Location: Philadelphia, PA
Posts: 6,659
Lil' Lavery has a reputation beyond reputeLil' Lavery has a reputation beyond reputeLil' Lavery has a reputation beyond reputeLil' Lavery has a reputation beyond reputeLil' Lavery has a reputation beyond reputeLil' Lavery has a reputation beyond reputeLil' Lavery has a reputation beyond reputeLil' Lavery has a reputation beyond reputeLil' Lavery has a reputation beyond reputeLil' Lavery has a reputation beyond reputeLil' Lavery has a reputation beyond repute
Send a message via AIM to Lil' Lavery
Re: CIMs, Weight, and Max Speed

Yes, you will have noticeably different performance between 60lbs and 120lbs.
__________________
Being correct doesn't mean you don't have to explain yourself.
Reply With Quote
  #4   Spotlight this post!  
Unread Today, 19:58
Cothron Theiss's Avatar
Cothron Theiss Cothron Theiss is online now
Registered Muser
FRC #4462 (Full Metal Jackets)
Team Role: College Student
 
Join Date: Feb 2016
Rookie Year: 2013
Location: Kingston, Tennessee
Posts: 605
Cothron Theiss has a reputation beyond reputeCothron Theiss has a reputation beyond reputeCothron Theiss has a reputation beyond reputeCothron Theiss has a reputation beyond reputeCothron Theiss has a reputation beyond reputeCothron Theiss has a reputation beyond reputeCothron Theiss has a reputation beyond reputeCothron Theiss has a reputation beyond reputeCothron Theiss has a reputation beyond reputeCothron Theiss has a reputation beyond reputeCothron Theiss has a reputation beyond repute
Re: CIMs, Weight, and Max Speed

You can use the JVN Mechanical Design Calculator to calculate more accurate (not perfectly accurate, but very good) speeds for your robot.
__________________
"It's taking longer than expected, which was to be expected."
Reply With Quote
  #5   Spotlight this post!  
Unread Today, 20:12
bc414 bc414 is online now
Registered User
FRC #1403
 
Join Date: Feb 2017
Location: New Jersey
Posts: 4
bc414 is an unknown quantity at this point
Re: CIMs, Weight, and Max Speed

If we strap on some metal blocks in order to increase the weight of the drive train to 120 lbs, will the drive train act similarly, or will the location of the center of mass change things? Is there anything else wrong with this approach?
Reply With Quote
  #6   Spotlight this post!  
Unread Today, 20:15
elijah1111's Avatar
elijah1111 elijah1111 is online now
Registered User
FRC #4601 (Circuit Birds)
Team Role: Programmer
 
Join Date: Jan 2017
Rookie Year: 2015
Location: Ohio
Posts: 25
elijah1111 is an unknown quantity at this point
Re: CIMs, Weight, and Max Speed

Quote:
Originally Posted by bc414 View Post
Will a 2 CIM per side drive train have a reduction in maximum speed when going from a 60 pound load to a 120 pound load? I am hoping to program autonomous using just the drive train and the electrical board while the rest of the robot is being built, but the algorithms I am using are dependent on the maximum speed of the robot.
If you are using encoders the speed would not matter. You could just read shaft revolutions.
Reply With Quote
  #7   Spotlight this post!  
Unread Today, 20:28
ctt956 ctt956 is online now
Week 6 already!?
FRC #0900 (♞The Zebracorns♞)
Team Role: Student
 
Join Date: Oct 2015
Rookie Year: 2016
Location: Planet Earth
Posts: 716
ctt956 is a splendid one to beholdctt956 is a splendid one to beholdctt956 is a splendid one to beholdctt956 is a splendid one to beholdctt956 is a splendid one to beholdctt956 is a splendid one to behold
Re: CIMs, Weight, and Max Speed

Quote:
Originally Posted by bc414 View Post
If we strap on some metal blocks in order to increase the weight of the drive train to 120 lbs, will the drive train act similarly, or will the location of the center of mass change things? Is there anything else wrong with this approach?
There will be some differences with air resistance(though probably insignificant), weight distribution, and weight transfer when moving. Though I'm not sure how big of a difference any of these would be. If you do strap on metal blocks, make sure they're secured well so they don't go flying.
__________________

"You know, it's amazing how many things you can take apart with just one ordinary screwdriver!" - Calvin, from Calvin and Hobbes
"There's nothing a little duct tape and surgical tubing can't accomplish." - Sheldon J. Plankton
Reply With Quote
  #8   Spotlight this post!  
Unread Today, 20:29
pmattin5459's Avatar
pmattin5459 pmattin5459 is online now
Registered User
AKA: Patrick Mattin
FRC #5459 (Ipswich TIGERS)
Team Role: Mentor
 
Join Date: Mar 2016
Rookie Year: 2015
Location: Massachusetts
Posts: 88
pmattin5459 will become famous soon enoughpmattin5459 will become famous soon enough
Re: CIMs, Weight, and Max Speed

Quote:
Originally Posted by elijah1111 View Post
If you are using encoders the speed would not matter. You could just read shaft revolutions.
And I would recommend using encoders. Any system not measuring the motor's output is highly theoretical and can be influenced negatively by a variety of real-world factors, including friction in the gearboxes, differing traction on each side due to weight distrobution, etc.
Reply With Quote
  #9   Spotlight this post!  
Unread Today, 20:39
bc414 bc414 is online now
Registered User
FRC #1403
 
Join Date: Feb 2017
Location: New Jersey
Posts: 4
bc414 is an unknown quantity at this point
Re: CIMs, Weight, and Max Speed

Quote:
Originally Posted by pmattin5459 View Post
And I would recommend using encoders. Any system not measuring the motor's output is highly theoretical and can be influenced negatively by a variety of real-world factors, including friction in the gearboxes, differing traction on each side due to weight distrobution, etc.
We are indeed using encoders. We are using Team 254's TrajectoryLib found here: https://github.com/Team254/TrajectoryLib
The algorithm calculates smooth position and velocity curves in order to get the robot to follow a smooth path. As the robot follows the path, the algorithm compares the position measured by encoders to the theoretical position and adjusts motor output accordingly.

The reason I'm asking about maximum velocity is because the algorithm requires the maximum velocity of the robot in order to generate the path and to set the motor outputs correctly.
Reply With Quote
Reply


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


All times are GMT -5. The time now is 20:42.

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