Go to Post Yay for teaching how to fish! - RoboMom [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

 
Reply
Thread Tools Rate Thread Display Modes
  #1   Spotlight this post!  
Unread 01-11-2018, 05:21 AM
Mr.R^2 Mr.R^2 is offline
Registered User
FRC #6762
 
Join Date: Apr 2017
Location: Hillsboro, NH
Posts: 47
Mr.R^2 is on a distinguished road
Possible heat buildup conciderations?

As our team is designing and building our bot for 2018, I am remembering some of the excellently designed control layouts we saw last year (our rookie) that put most of the control system in essentially a plastic box mounted to either the chassis or the top of the robot. We are considering creating something similar this year, but have some questions about heat.

1) Since space could be problematic in our design, if we keep speed controllers out of the box, and made it just a bit taller than the Rio and IMU in the expansion port, should we be concerned about heat buildup in the box?

2) If we put, say, 4 talons in the box as well (for the drive motors), would that begin to create concern about heat?

3)Are we able to legally, and if so should we consider a fan or is that necessary?

Thanks.
~R^2

Sent from my SM-T810 using Tapatalk
Reply With Quote
  #2   Spotlight this post!  
Unread 01-11-2018, 06:55 AM
gerthworm's Avatar
gerthworm gerthworm is offline
Making the 1's and 0's
FRC #1736 (Robot Casserole)
Team Role: Mentor
 
Join Date: Jan 2015
Rookie Year: 2015
Location: Peoria, IL
Posts: 412
gerthworm has a reputation beyond reputegerthworm has a reputation beyond reputegerthworm has a reputation beyond reputegerthworm has a reputation beyond reputegerthworm has a reputation beyond reputegerthworm has a reputation beyond reputegerthworm has a reputation beyond reputegerthworm has a reputation beyond reputegerthworm has a reputation beyond reputegerthworm has a reputation beyond reputegerthworm has a reputation beyond repute
Re: Possible heat buildup conciderations?

Although having ventilation and a fan would be nice in said box, I feel like heat buildup would be pretty negligible, especially over a two-minute match.

I believe a small computer fan should be ok. We almost always mount one over our air compressor to keep its temperature down over long practice sessions.
Reply With Quote
  #3   Spotlight this post!  
Unread 01-11-2018, 08:57 AM
hrench's Avatar
hrench hrench is offline
mechanical build mentor
AKA: Bob Hrenchir
FRC #1108 (Panther Robotics)
Team Role: Mentor
 
Join Date: Jan 2012
Rookie Year: 2010
Location: Paola, KS
Posts: 340
hrench has a brilliant futurehrench has a brilliant futurehrench has a brilliant futurehrench has a brilliant futurehrench has a brilliant futurehrench has a brilliant futurehrench has a brilliant futurehrench has a brilliant futurehrench has a brilliant futurehrench has a brilliant futurehrench has a brilliant future
Re: Possible heat buildup conciderations?

NI publishes that the RoboRio can use from 5-45 watts. The IMU uses about a tenth of a watt.

http://www.ni.com/pdf/manuals/375275a.pdf

https://www.sparkfun.com/datasheets/...00-00-01.4.pdf


In a vented enclosure with some natural convection, 0.15 watts/cuin is a guideline for power density. For forced convection (fan) you can use power densities up to about 1watt/cuin

So for the RIO and the IMU, the maximum you'd need would be an enclosure about 300 cubic inches with no fan and 45 cuin with a fan. I'm not sure, but I doubt it would even fit in an enclosure that small.

But motor controllers are much hotter. I don't find efficiency posted on Victor's page, but in general, I think you'd expect them to be something like 95 percent efficient. So if you're running a 350 watt CIM, you'll see about 18 watts of heat coming from each motor controller while it has that high load.
These can add up pretty fast. That's why they have fins to reject heat.

I would never recommend that you put motor controllers in any kind of enclosure. If you keep the motor controllers out of the box, you'll be fine, fan or not.

But as a fact, these are equations that are for designing electronics that run steady-state for long times. If your robot just does a three-minute match and then you shut down, it will never build up much heat. If you run it in a parade, that would be a different situation.

My team never uses an enclosure because they just add weight. You can "enclose" within a corner of the frame nearly as well.

Here's a couple links to enclosure heat design references that I've used in my job as an electronics packaging engineer.

http://www.hoffmanonline.com/stream_...09&pRID=162533

https://books.google.com/books?id=JQ...20inch&f=false
Reply With Quote
  #4   Spotlight this post!  
Unread 01-11-2018, 09:11 AM
GeeTwo's Avatar
GeeTwo GeeTwo is offline
Mentor
AKA: Gus Michel II
FRC #3946 (Tiger Robotics)
Team Role: Mentor
 
Join Date: Jan 2014
Rookie Year: 2013
Location: Slidell, LA
Posts: 5,420
GeeTwo has a reputation beyond reputeGeeTwo has a reputation beyond reputeGeeTwo has a reputation beyond reputeGeeTwo has a reputation beyond reputeGeeTwo has a reputation beyond reputeGeeTwo has a reputation beyond reputeGeeTwo has a reputation beyond reputeGeeTwo has a reputation beyond reputeGeeTwo has a reputation beyond reputeGeeTwo has a reputation beyond reputeGeeTwo has a reputation beyond repute
Re: Possible heat buildup conciderations?

Quote:
Originally Posted by gerthworm View Post
Although having ventilation and a fan would be nice in said box, I feel like heat buildup would be pretty negligible, especially over a two-minute match.
The greatest stress situation here is likely to be drive practice, not matches. We don't enclose our controls, but often put a cover over them to keep out game pieces, etc. However, some years we do most of our drive practice with the cover off.
__________________

If you can't find time to do it right, how are you going to find time to do it over?
If you don't pass it on, it never happened.
Robots are great, but inspiration is the reason we're here.
Friends don't let friends use master links.
Reply With Quote
  #5   Spotlight this post!  
Unread 01-12-2018, 08:24 PM
SwissArmy4057's Avatar
SwissArmy4057 SwissArmy4057 is offline
Registered User
FRC #4057 (STEAMPUNK Robotics)
Team Role: Mechanical
 
Join Date: Jan 2016
Rookie Year: 2014
Location: Klamath Falls, OR
Posts: 25
SwissArmy4057 is an unknown quantity at this point
Re: Possible heat buildup conciderations?

Fans are legal as they are considered a COTS part, unless you're building your own squirrel-cage blower with a 775.

In competition heat won't be an issue. Things may get warm but it's unlikely to overheat in only 2 1/2 minutes. Practice driving is a different story.

I'd say slap a 80mm computer fan on the lowest part of the box, cut a few ventilation slots in the highest part and have extra peace of mind from knowing your precious pieces of silicon are being kept cozy.
Reply With Quote
  #6   Spotlight this post!  
Unread 01-13-2018, 09:11 AM
Mr.R^2 Mr.R^2 is offline
Registered User
FRC #6762
 
Join Date: Apr 2017
Location: Hillsboro, NH
Posts: 47
Mr.R^2 is on a distinguished road
Thanks everyone. This is extremely helpful.
Reply With Quote
  #7   Spotlight this post!  
Unread 01-13-2018, 10:11 AM
philso philso is offline
Mentor
no team
 
Join Date: Jan 2011
Rookie Year: 2009
Location: Houston, Tx
Posts: 1,491
philso has a reputation beyond reputephilso has a reputation beyond reputephilso has a reputation beyond reputephilso has a reputation beyond reputephilso has a reputation beyond reputephilso has a reputation beyond reputephilso has a reputation beyond reputephilso has a reputation beyond reputephilso has a reputation beyond reputephilso has a reputation beyond reputephilso has a reputation beyond repute
Re: Possible heat buildup conciderations?

Quote:
Originally Posted by Mr.R^2 View Post
As our team is designing and building our bot for 2018, I am remembering some of the excellently designed control layouts we saw last year (our rookie) that put most of the control system in essentially a plastic box mounted to either the chassis or the top of the robot. We are considering creating something similar this year, but have some questions about heat.

1) Since space could be problematic in our design, if we keep speed controllers out of the box, and made it just a bit taller than the Rio and IMU in the expansion port, should we be concerned about heat buildup in the box?

2) If we put, say, 4 talons in the box as well (for the drive motors), would that begin to create concern about heat?

3)Are we able to legally, and if so should we consider a fan or is that necessary?

Thanks.
~R^2

Sent from my SM-T810 using Tapatalk
Is there a reason your team feels that an enclosure is necessary, other than aesthetics? There are also many, many examples of great electrical layouts done on a panel with a simple protective cover that work just as well and require less in terms of design time and manufacturing resources. The designs based on a panel are also probably easier to troubleshoot, easier to maintain and easier to make modifications to. Your team would most likely gain more benefit by applying that design time and manufacturing resources on actual scoring mechanisms.
Reply With Quote
  #8   Spotlight this post!  
Unread 01-17-2018, 02:08 PM
Mr.R^2 Mr.R^2 is offline
Registered User
FRC #6762
 
Join Date: Apr 2017
Location: Hillsboro, NH
Posts: 47
Mr.R^2 is on a distinguished road
Thank you. We were actually planning on a panel with a cover. I guess I communicated our ideas inaccurately. Last year, we did not cover the panel and had a few game piece related faults. So, that is the reason for the design update. We are aware that the game pieces are larger, but our robot design will probably be a lot more open this year too.
Reply With Quote
  #9   Spotlight this post!  
Unread 01-17-2018, 02:58 PM
MrForbes's Avatar
MrForbes MrForbes is online now
Registered User
AKA: Jim
FRC #1726 (N.E.R.D.S.)
Team Role: Mentor
 
Join Date: Feb 2006
Rookie Year: 2006
Location: Sierra Vista AZ
Posts: 6,384
MrForbes has a reputation beyond reputeMrForbes has a reputation beyond reputeMrForbes has a reputation beyond reputeMrForbes has a reputation beyond reputeMrForbes has a reputation beyond reputeMrForbes has a reputation beyond reputeMrForbes has a reputation beyond reputeMrForbes has a reputation beyond reputeMrForbes has a reputation beyond reputeMrForbes has a reputation beyond reputeMrForbes has a reputation beyond repute
Re: Possible heat buildup conciderations?

We never have worried about heat build up, and never had issues with it. We have put our electronics in a covered box a few times, usually when the robot configuration allows us to put the box vertical, so the covered side faces outside the robot. A sliding, clear plastic cover lets us have easy access, and protects stuff from damage. Also having the box oriented this way keeps swarf out of the electronics, when we're working feverishly on the robot between matches.
Reply With Quote
  #10   Spotlight this post!  
Unread 01-20-2018, 11:38 AM
Unsung FIRST Hero
Al Skierkiewicz Al Skierkiewicz is offline
Broadcast Eng/Chief Robot Inspector
AKA: Big Al WFFA 2005
FRC #0111 (WildStang)
Team Role: Engineer
 
Join Date: Jun 2001
Rookie Year: 1996
Location: Wheeling, IL
Posts: 11,071
Al Skierkiewicz has a reputation beyond reputeAl Skierkiewicz has a reputation beyond reputeAl Skierkiewicz has a reputation beyond reputeAl Skierkiewicz has a reputation beyond reputeAl Skierkiewicz has a reputation beyond reputeAl Skierkiewicz has a reputation beyond reputeAl Skierkiewicz has a reputation beyond reputeAl Skierkiewicz has a reputation beyond reputeAl Skierkiewicz has a reputation beyond reputeAl Skierkiewicz has a reputation beyond reputeAl Skierkiewicz has a reputation beyond repute
Re: Possible heat buildup conciderations?

Yes controllers can get hot in a two minute match. However, please consider that electrical components need to be seen during inspection and while on the field. There are several rules that need to be satisfied. (such as R50 and R70)
Please also consider Al's corollary to Murphy's Law, "Anything that can go wrong will go wrong on Einstein."
__________________
Good Luck All. Learn something new, everyday!
Al
WB9UVJ
www.wildstang.org
________________________
Knowledge is power. Power UP!
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 09:08 PM.

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


Powered by vBulletin® Version 3.6.4
Copyright ©2000 - 2018, Jelsoft Enterprises Ltd.
Copyright © Chief Delphi