OCCRA
Go to Post We are not here to build robots, or to win a contest, or to travel to cool places or to bring home trophies. we are here to see what a career in engineering and science is like; anything else that happens along the way is frosting on the cake - KenWittlief [more]
Home
Go Back   Chief Delphi > Technical > Electrical
CD-Media  
portal register members calendar search Today's Posts Mark Forums Read FAQ rules

 
Reply
Thread Tools Rate Thread Display Modes
  #16   Spotlight this post!  
Unread 09-27-2018, 11:19 AM
MrForbes's Avatar
MrForbes MrForbes is offline
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: 6,409
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: Best placement for electrical components

Figuring out where to put the electronics on a robot, is an exercise in dealing with conflicting requirements.

GeeTwo has a pretty good explanation of what to do, as I see it.

It really helps if someone who's been around robots a while, is overseeing the design of the whole thing. If you don't have that person on your team, you're probably going to learn some lessons the hard way...and as a result, you will get some of that necessary but costly experience!

have fun
Reply With Quote
  #17   Spotlight this post!  
Unread 09-27-2018, 11:28 AM
couvillion couvillion is offline
Registered User
FRC #1818
Team Role: Mentor
 
Join Date: Feb 2011
Rookie Year: 2011
Location: shreveport LA
Posts: 70
couvillion is an unknown quantity at this point
Re: Best placement for electrical components

One idea I'll throw out is that if you can put the PDP and RoboRio back to back on opposite sides of a board and keep power and control separated it really helps keeps things clear.

In a perfect world you'd be able to disconnect the actuators and lift it out of the robot.
Reply With Quote
  #18   Spotlight this post!  
Unread 09-27-2018, 12:54 PM
Unsung FIRST Hero
Al Skierkiewicz Al Skierkiewicz is offline
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: 11,116
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: Best placement for electrical components

WildStang has conflicts with mechanical over placement of electronics most years. We deal with it creatively and with lots of discussion.

1. Center your PDP so that drive train wiring is nearly equal length. (See post above, you will have a very difficult time getting auto to work because the robot will not drive straight)
2. Make high current wiring as short as possible. That is all #6 AWG wire. The more #6 you add, the greater the risk of brownout. All robot current passes through this wire and it has resistance.
3. Low current items like the PCM, VRM, and RoboRio can be placed where they fit. However, the PCM, PDP and compressor should be close. The compressor draws maximum current when starting.
4. Using lower current rated breakers does nothing to limit current. A
CIM motor in stall will draw 131 amps through a 20, a 30 or a 40 amp breaker.
5. Use short, large diameter wire for high current loads. #12 AWG for drive motors, #10 AWG is better.
6. If you use crimp terminals make sure they are crimped properly. Every crimp will add resistance, a poorly crimped terminal will add more resistance. Consider soldering crimped connections to insure low resistance connections.
7. Be sure to strip wire insulation as recommended by the manufacturer. Wire for the PDP should be 1/2-5/8 inch.

Quack, sometime in the future, perhaps I can visit and explain this further.
__________________
Good Luck All. Learn something new, everyday!
Al
WB9UVJ
www.wildstang.org
________________________
Knowledge is power. Power UP!
Reply With Quote
  #19   Spotlight this post!  
Unread 09-27-2018, 01:06 PM
dtengineering's Avatar
dtengineering dtengineering is offline
Teaching Teachers to Teach Tech
AKA: Jason Brett
no team (British Columbia FRC teams)
Team Role: Mentor
 
Join Date: Jan 2005
Rookie Year: 2004
Location: Vancouver, BC
Posts: 1,996
dtengineering has a reputation beyond reputedtengineering has a reputation beyond reputedtengineering has a reputation beyond reputedtengineering has a reputation beyond reputedtengineering has a reputation beyond reputedtengineering has a reputation beyond reputedtengineering has a reputation beyond reputedtengineering has a reputation beyond reputedtengineering has a reputation beyond reputedtengineering has a reputation beyond reputedtengineering has a reputation beyond repute
Re: Best placement for electrical components

Quote:
Originally Posted by couvillion View Post
In a perfect world you'd be able to disconnect the actuators and lift it out of the robot.
In 2010 we built a "control box" that had all the expensive stuff in it... solenoid valves, all the electronics... and screw terminals for connecting the heavy stuff... the motors and such, to the box.

This let us build two robots, practice with one, and then carry our control box in to the competition as part of our withholding allowance. It took about half an hour to install the box and then we were up and running with a mostly identical clone to the machine we had been practicing with.

It's a good strategy for teams who want the benefit of a practice robot without the expense of two control systems. Here's a photo of the two of them... unfortunately it doesn't show the box. https://www.chiefdelphi.com/forums/s...highlight=1346

Jason
Reply With Quote
  #20   Spotlight this post!  
Unread 09-27-2018, 01:27 PM
Jon Stratis's Avatar
Jon Stratis Jon Stratis is offline
Mentor, LRI, MN RPC
FRC #2177 (The Robettes)
Team Role: Mentor
 
Join Date: Feb 2007
Rookie Year: 2006
Location: Minnesota
Posts: 5,125
Jon Stratis has a reputation beyond reputeJon Stratis has a reputation beyond reputeJon Stratis has a reputation beyond reputeJon Stratis has a reputation beyond reputeJon Stratis has a reputation beyond reputeJon Stratis has a reputation beyond reputeJon Stratis has a reputation beyond reputeJon Stratis has a reputation beyond reputeJon Stratis has a reputation beyond reputeJon Stratis has a reputation beyond reputeJon Stratis has a reputation beyond repute
Re: Best placement for electrical components

Quote:
Originally Posted by dtengineering View Post
In 2010 we built a "control box" that had all the expensive stuff in it... solenoid valves, all the electronics... and screw terminals for connecting the heavy stuff... the motors and such, to the box.
For those considering such a design, please keep in mind inspectability and maintainability. Inspectors need to be able to see breaker values and wire gauges. We need to be able to trace certain wires, like those powering the RoboRio and the VRM that powers the radio, to ensure devices are being powered from the correct locations. As a team, you want diagnostic LED's visible during operation - those on the RoboRio should be visible to the FTA or CSA on the field, and you'll want to be able to see those present on your speed controllers when something isn't working right. When designing a control box, these considerations are often the first team's forget about in their rush to make it as small and compact as possible.

I'll share a few stories to help illustrate how important the above considerations are.

This past year, a team at one of my events had such a control box. Very small and compact, but it was impossible to see the breaker values in order to properly inspect it. They proceeded to spend over an hour disassembling the box so the inspector could look at it, and then reassembling it. That's valuable time at an event where their robot wasn't operational. Later in the event, they ran into an issue (with their CAN bus, I believe) that forced them to call in a backup robot during the playoffs - it simply took too long to disassemble the box and find the issue.

This year my team had an unfortunate issue with some crossed wires - we miss-wired our intake and one side of our drive train. One of the drive motors was being controlled by an intake speed controller, and one side of the intake was being controlled by one of the drive speed controllers. In the end, we identified the issue by looking at the diagnostic LED's on the speed controllers and realizing they weren't doing what we expected. After that, the fix was easy.

At an off-season event just this past weekend a robot died near the end of the first finals match. It was near the edge of the arena, and myself, the FTA and a CSA were able to observe that the radio and speed controllers were just fine, but the RoboRio had no power. After the match we helped with some additional diagnostics, and after removing the RoboRio discovered that it was internally shorted by some robot debris. After cleaning it out, they got back up and running. They missed the second match, but were able to come back in for the tiebreaker match - and that was only possible because their RoboRio was easily accessible!
__________________
LRI: North Star 2012-2016; Lake Superior 2013-2014; MN State Tournament 2013-2014, 2016-2018; Iowa 2017; Northern Lights 2018; Great Northern 2018-2019
Division LRI: Galileo 2016; Tesla 2017; Archimedes 2018
2015: North Star Regional Volunteer of the Year
2016: Lake Superior WFFA
Reply With Quote
  #21   Spotlight this post!  
Unread 09-27-2018, 01:31 PM
philso philso is offline
Mentor
no team
 
Join Date: Jan 2011
Rookie Year: 2009
Location: Houston, Tx
Posts: 1,707
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: Best placement for electrical components

Quote:
Originally Posted by couvillion View Post
One idea I'll throw out is that if you can put the PDP and RoboRio back to back on opposite sides of a board and keep power and control separated it really helps keeps things clear.
If you do this, make sure that both sides is accessible for inspection, troubleshooting, repair and modification.

Quote:
Originally Posted by Al Skierkiewicz View Post
6. If you use crimp terminals make sure they are crimped properly. Every crimp will add resistance, a poorly crimped terminal will add more resistance. Consider soldering crimped connections to insure low resistance connections.
7. Be sure to strip wire insulation as recommended by the manufacturer. Wire for the PDP should be 1/2-5/8 inch.
A ratcheting crimper will give the most reliable crimps.

Solder only if you know how to solder properly. Otherwise, you can actually make things worse. Not all soldering irons/tips are capable of soldering on 12~10 AWG wire.

The strip length Al gives sounds about right for the power wires going into the WAGO connectors on the PDP. The PDP Users Guide recommends a strip length of 3/8" for the smaller wires that go into the Weidmuller connectors.
Reply With Quote
  #22   Spotlight this post!  
Unread 09-27-2018, 03:06 PM
Type's Avatar
Type Type is offline
Registered User
AKA: AJ
FRC #3452 (GreengineerZ)
Team Role: Mechanical
 
Join Date: Jan 2016
Rookie Year: 2016
Location: Michigan
Posts: 465
Type has much to be proud ofType has much to be proud ofType has much to be proud ofType has much to be proud ofType has much to be proud ofType has much to be proud ofType has much to be proud ofType has much to be proud ofType has much to be proud of
Re: Best placement for electrical components

This previous year, my team had somewhat of spread out electronics. We CADed some of it, but just general making sure its gonna fit. We placed the PDP in the center of the robot and located the VRMs (one for POE, one for barrel jack) right in front of the PDP. Located between our drive gearboxes in the rear, we had 2 sets of Talon Blocks as we called in. We have been doing this for a couple years but attach SRXs on a piece of sheet vertical sheet metal (3" tall probably) and attach 2 to each side to create little blocks that allow us to still see the lights but in a compact space. We located one of these blocks up front near our elevator also. This moves the electronics away from the center but allows for room around the electronics for easy reach (messing with data cables, resetting, etc.). Finally, we stacked our roboRio over our PDP on a hinge to save space, and allow us to open it for inspection. Incase the roboRio needed removed to get better access to the PDP, there were 2 screws located under the robot that would release it.

EDIT: Pictures http://imgur.com/a/6AlerR0
The Rio over PDP shown is from stripped practice bot. Comp bot is in better shape so harder to get picture, but same layout.
__________________
3452- Lead Builder/ Pit Boss




*My posts do not reflect the opinion of my team*

Last edited by Type : 09-27-2018 at 03:14 PM.
Reply With Quote
  #23   Spotlight this post!  
Unread 09-27-2018, 03:59 PM
MooreteP's Avatar
MooreteP MooreteP is offline
Zen Archer
AKA: Senor Mas
FRC #0571 (Team Paragon)
Team Role: Mentor
 
Join Date: Mar 2004
Rookie Year: 1998
Location: Windsor CT
Posts: 934
MooreteP has a reputation beyond reputeMooreteP has a reputation beyond reputeMooreteP has a reputation beyond reputeMooreteP has a reputation beyond reputeMooreteP has a reputation beyond reputeMooreteP has a reputation beyond reputeMooreteP has a reputation beyond reputeMooreteP has a reputation beyond reputeMooreteP has a reputation beyond reputeMooreteP has a reputation beyond reputeMooreteP has a reputation beyond repute
Re: Best placement for electrical components

Quote:
Originally Posted by Thequackmaster View Post
I was wondering about other teams ideas of where the put their power distribution panels, voltage regulator module and so forth because on our 2018 robot.
Above the Waterline.
Reply With Quote
  #24   Spotlight this post!  
Unread 09-27-2018, 04:01 PM
risho900 risho900 is online now
Registered User
FRC #6897 (Astraea Robotics)
 
Join Date: May 2018
Rookie Year: 2015
Location: East Brunswick
Posts: 203
risho900 is a name known to allrisho900 is a name known to allrisho900 is a name known to allrisho900 is a name known to allrisho900 is a name known to allrisho900 is a name known to all
Re: Best placement for electrical components

Quote:
Originally Posted by Al Skierkiewicz View Post
WildStang has conflicts with mechanical over placement of electronics most years. We deal with it creatively and with lots of discussion.

1. Center your PDP so that drive train wiring is nearly equal length. (See post above, you will have a very difficult time getting auto to work because the robot will not drive straight)
2. Make high current wiring as short as possible. That is all #6 AWG wire. The more #6 you add, the greater the risk of brownout. All robot current passes through this wire and it has resistance.
3. Low current items like the PCM, VRM, and RoboRio can be placed where they fit. However, the PCM, PDP and compressor should be close. The compressor draws maximum current when starting.
4. Using lower current rated breakers does nothing to limit current. A
CIM motor in stall will draw 131 amps through a 20, a 30 or a 40 amp breaker.
5. Use short, large diameter wire for high current loads. #12 AWG for drive motors, #10 AWG is better.
6. If you use crimp terminals make sure they are crimped properly. Every crimp will add resistance, a poorly crimped terminal will add more resistance. Consider soldering crimped connections to insure low resistance connections.
7. Be sure to strip wire insulation as recommended by the manufacturer. Wire for the PDP should be 1/2-5/8 inch.

Quack, sometime in the future, perhaps I can visit and explain this further.
If the breaker still allows a CIM to draw 131 A of current, then what exactly is its function?
Reply With Quote
  #25   Spotlight this post!  
Unread 09-27-2018, 04:16 PM
Jon Stratis's Avatar
Jon Stratis Jon Stratis is offline
Mentor, LRI, MN RPC
FRC #2177 (The Robettes)
Team Role: Mentor
 
Join Date: Feb 2007
Rookie Year: 2006
Location: Minnesota
Posts: 5,125
Jon Stratis has a reputation beyond reputeJon Stratis has a reputation beyond reputeJon Stratis has a reputation beyond reputeJon Stratis has a reputation beyond reputeJon Stratis has a reputation beyond reputeJon Stratis has a reputation beyond reputeJon Stratis has a reputation beyond reputeJon Stratis has a reputation beyond reputeJon Stratis has a reputation beyond reputeJon Stratis has a reputation beyond reputeJon Stratis has a reputation beyond repute
Re: Best placement for electrical components

Quote:
Originally Posted by risho900 View Post
If the breaker still allows a CIM to draw 131 A of current, then what exactly is its function?
It's designed to protect the wiring on the circuit. During use, wire heats up from the current travelling through it. Based on the gauge of the wire, there's a certain amount of heat that can safely dissipate. If you push too much current through the wire, the amount of heat build up exceeds the amount dissipating, eventually leading to the insulation and wire itself burning up.

Here is the datasheet for the 20A snap action breaker. At 133A (665% of rated current) it takes something like 1/2 second to trip. During that time, the wire would heat up... but then the breaker tripping, and cutting off all power, allows the excess heat to dissipate safely while there is no additional heat being generated (no current travelling through the wire).

So the CIM motor can pull 133A. The breaker tripping breaks the circuit for a short period, until the breaker resets. Once it does, the motor can pull 133 A again instantly, tripping the breaker again. So it doesn't change how much current the motor can draw, only the length of time it can draw it. Since breakers are temperature based devices (they use a build up of heat to cause a physical movement to disconnect the circuit, then upon cooling down physically move back to reconnect the circuit), after tripping and resetting the temperature is already elevated and it's quicker to trip if the current draw is still exceeded.
__________________
LRI: North Star 2012-2016; Lake Superior 2013-2014; MN State Tournament 2013-2014, 2016-2018; Iowa 2017; Northern Lights 2018; Great Northern 2018-2019
Division LRI: Galileo 2016; Tesla 2017; Archimedes 2018
2015: North Star Regional Volunteer of the Year
2016: Lake Superior WFFA
Reply With Quote
  #26   Spotlight this post!  
Unread 09-27-2018, 04:22 PM
AriMB's Avatar
AriMB AriMB is online now
The Philadelphian emigrant
AKA: Ari Meles-Braverman
FRC #5987 (Galaxia)
Team Role: Mentor
 
Join Date: Mar 2015
Rookie Year: 2012
Location: Haifa, Israel
Posts: 1,761
AriMB has a reputation beyond reputeAriMB has a reputation beyond reputeAriMB has a reputation beyond reputeAriMB has a reputation beyond reputeAriMB has a reputation beyond reputeAriMB has a reputation beyond reputeAriMB has a reputation beyond reputeAriMB has a reputation beyond reputeAriMB has a reputation beyond reputeAriMB has a reputation beyond reputeAriMB has a reputation beyond repute
Re: Best placement for electrical components

Quote:
Originally Posted by risho900 View Post
If the breaker still allows a CIM to draw 131 A of current, then what exactly is its function?
If the motor draws over the breaker's limit*, it breaks the circuit, stopping the motor. Since these are self-resetting breakers, they will re-close the circuit after some time. If the CIM motor is still stalled, it will go back to drawing 131A, and the breaker will break again. And so the cycle continues.

* for a certain amount of time, see the datasheets

edit: sniped
__________________
Studying MechE at the Technion - Israel Institute of Technology
2017-present: FIRST Israel CSA/FTAA
2017-present: FRC 5987 Technical Mentor 18isr2 18isr4 18isrcmp 18carv
2012-2016: FRC 423 Member 15njtab 15padre 16paphi
Reply With Quote
  #27   Spotlight this post!  
Unread 09-27-2018, 04:51 PM
philso philso is offline
Mentor
no team
 
Join Date: Jan 2011
Rookie Year: 2009
Location: Houston, Tx
Posts: 1,707
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: Best placement for electrical components

Quote:
Originally Posted by risho900 View Post
If the breaker still allows a CIM to draw 131 A of current, then what exactly is its function?
The "Melting Integral", "Time vs Current Curves" and "Surge and Pulse Current Characteristics" sections of this fuse application note explains why currents higher than the rating of a protection device can flow through the device. The thermal breakers used in FRC operate (trip) in a similar fashion. I tried to find similar documents for breakers but they were all for thermal-magnetic breakers which are a bit more complicated in how they work.
Reply With Quote
  #28   Spotlight this post!  
Unread 09-30-2018, 10:28 AM
Unsung FIRST Hero
Al Skierkiewicz Al Skierkiewicz is offline
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: 11,116
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: Best placement for electrical components

risho,
In a simple explanation, the breakers are chosen to protect branch circuit in the event of a short. Fire on the field is a bad thing.
Due to the trip characteristics of the breaker they can withstand the 600% over current for a short period of time. This does not prevent a driver from pushing the robot against an immovable object for several seconds. In general, with all of the other losses on the robot, even a stalled CIM motor is unlikely to draw 131 amps. However, there are conditions where the breaker may not fully protect a speed controller max current specifications. The breaker is not intended to protect devices connected to it, merely to prevent fire in a catastrophic failure.
Likewise the 120 amp breaker has a similar 600% over current response except, it is not auto-resetting.
__________________
Good Luck All. Learn something new, everyday!
Al
WB9UVJ
www.wildstang.org
________________________
Knowledge is power. Power UP!
Reply With Quote
  #29   Spotlight this post!  
Unread 09-30-2018, 11:19 AM
risho900 risho900 is online now
Registered User
FRC #6897 (Astraea Robotics)
 
Join Date: May 2018
Rookie Year: 2015
Location: East Brunswick
Posts: 203
risho900 is a name known to allrisho900 is a name known to allrisho900 is a name known to allrisho900 is a name known to allrisho900 is a name known to allrisho900 is a name known to all
Re: Best placement for electrical components

Ah I see thanks a lot fellows.
Reply With Quote
  #30   Spotlight this post!  
Unread 10-01-2018, 10:10 AM
CooperWard4499 CooperWard4499 is offline
Registered User
FRC #4499
 
Join Date: May 2018
Location: Ft. Collins, CO
Posts: 5
CooperWard4499 is an unknown quantity at this point
Re: Best placement for electrical components

As someone who had this problem before, our 2018 year I went with an upside down electronics design. This allowed us to have plenty of space for components and wire placement, and we never had a major problem the whole year. However if this is not an option for you, here are some basics that I follow to make anything work well.

1. Place your PDP as close to the center of your robot as possible, this is to decrease wire lengths to all areas of the robot and have less extremely long wires, which can cause some voltage drop.

2. Group motor controllers close together, and put power wires from them directly into the PDP. Putting them directly into the PDP will have less resistance, and Grouping them together is extremely important for maintenance, as having to look around your whole robot for light codes is a pain.

3. Group wires that are going to the same places together. The easiest way to make it more manageable (and good looking) is to group wires together along set paths. For example, if you have a 6 CIM drive system, six of your motor controllers are going to those CIMS, so you can route all of their wires togther. The best example of this is from team 1538, whose electronics layout you can also learn a lot from.

Bonus tips: PROTECT EVERYTHING. Please don't run wires near an exposed gearbox without protection, it's just a really bad idea. Also make sure that nothing outside of your robot is able to take down your electrical or pneumatic system.

Pneumatics is another beast to tackle, but hope those help out!
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 08:23 AM.

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


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