OCCRA
Go to Post FIRST robots are not six week projects. They are never ending projects where the requirements are changed on an annual basis. - ChrisH [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
  #31   Spotlight this post!  
Unread 09-12-2017, 10:21 PM
SuperMario210 SuperMario210 is offline
Registered User
FRC #0254 (The Cheesy Poofs)
Team Role: Programmer
 
Join Date: Sep 2017
Rookie Year: 2015
Location: San Jose
Posts: 7
SuperMario210 is a splendid one to beholdSuperMario210 is a splendid one to beholdSuperMario210 is a splendid one to beholdSuperMario210 is a splendid one to beholdSuperMario210 is a splendid one to beholdSuperMario210 is a splendid one to beholdSuperMario210 is a splendid one to behold
Re: Team 254 Presents: 2017 Misfire Technical Binder and Build Blogs

Quote:
Originally Posted by buildmaster5000 View Post
One question I have reading through the binder (which is amazing!):

How did you develop your function to correlate shooter wheel speed to a function of distance, and how did you measure the distance?
To create our distance to shooter RPM function, we first collected a set of distance to RPM data points by fixing our shooter RPM to various values and finding the optimal distance for each RPM. We then used a quadratic polynomial regression to find the best fit function for these data points.

The general idea behind finding distance to the boiler is to find the vertical angle to the boiler then use trig/similar triangles to calculate distance from this angle. First we calculate the vertical angle between our camera and the vision tape using this equation: atan(y_pixel_position / focal_length) where a (0,0) pixel position is at the center of the screen. Once we have the vertical angle to the target we use some basic trig to calculate the distance to the boiler ( range = cot(vertical_angle) * height_difference where height_difference is the height difference between the camera and the boiler). We gave an in depth explanation about it at the Integrating Computer Vision with Motion Control presentation at the 2016 FIRST Championship.
Reply With Quote
  #32   Spotlight this post!  
Unread 09-12-2017, 10:29 PM
dardeshna's Avatar
dardeshna dardeshna is offline
Team Captain
AKA: Devin Ardeshna
FRC #0008 (Paly Robotics | Team 8)
Team Role: Mechanical
 
Join Date: Dec 2015
Rookie Year: 2015
Location: Palo Alto
Posts: 105
dardeshna is a name known to alldardeshna is a name known to alldardeshna is a name known to alldardeshna is a name known to alldardeshna is a name known to alldardeshna is a name known to all
Re: Team 254 Presents: 2017 Misfire Technical Binder and Build Blogs

Quote:
Originally Posted by buildmaster5000 View Post
One question I have reading through the binder (which is amazing!):

How did you develop your function to correlate shooter wheel speed to a function of distance, and how did you measure the distance?
Quote:
Originally Posted by TylerHarmon View Post
I'm not on 254, but according to the tech. binder: "An Interpolating Tree Map determines the correct flywheel RPM for the current distance"
I believe an Interpolating Tree Map is basically linear interpolation between several calibrated values.

Linear interpolation: Imagine a set of plotted points, then draw lines to connect them instead of fitting a curve to the data.
__________________
Devin Ardeshna
Team Captain (Paly Robotics FRC #8)


2017 Ventura Regional Quarterfinalist, Entrepreneurship Award, and Creativity Award, Silicon Valley Regional Finalist, Entrepreneurship Award, and Wildcard, Roebling Division Semifinalist
2016 Central Valley Regional Finalist and Wildcard, Silicon Valley Regional Quarterfinalist, Curie Division, CalGames Quarterfinalist and Entrepreneurship Award, Capital City Classic Quarterfinalist
2015 Central Valley Regional Entrepreneurship Award, Silicon Valley Regional Entrepreneurship Award, Capital City Classic Semifinalist and Judges' Award
Reply With Quote
  #33   Spotlight this post!  
Unread 09-12-2017, 11:16 PM
davispitts3577 davispitts3577 is offline
Registered User
FRC #3577 (Saints Robotics)
Team Role: Electrical
 
Join Date: Aug 2017
Rookie Year: 2017
Location: Arizona
Posts: 24
davispitts3577 is a splendid one to beholddavispitts3577 is a splendid one to beholddavispitts3577 is a splendid one to beholddavispitts3577 is a splendid one to beholddavispitts3577 is a splendid one to beholddavispitts3577 is a splendid one to beholddavispitts3577 is a splendid one to behold
Re: Team 254 Presents: 2017 Misfire Technical Binder and Build Blogs

Quote:
Originally Posted by Ashwin254Adulla View Post
To calculate the angle of the hood, we took into account where in the field we wanted to shoot from (front hopper during autonomous), where the hood would be vertically placed on the robot, and at approximately what angle we wanted the ball stream to enter the boiler. For SFR and SVR, our first iteration of the hood had a fairly shallow angle (around 20 degrees above the horizontal) which led to a non-optimal trajectory which gave us an accuracy of roughly 60-70% at these two regionals. For Champs, our priority was changing the hood to a) have less compression and b) reduce the angle to give us a better trajectory. To test out which angle we wanted, we went through a series of iterations consisting of placing blocks below the front of the robot to effectively decrease the exit angle of the balls and then translating that new effective angle into a CAD hood prototype which we laser cut and mounted in place of our current hood. We ran through around 5 iterations to get to our final hood angle of 14 degrees.
Just sent you a PM.
Reply With Quote
  #34   Spotlight this post!  
Unread 09-13-2017, 03:42 AM
Cory's Avatar
Cory Cory is offline
Registered User
AKA: Cory McBride
FRC #0254 (The Cheesy Poofs)
Team Role: Engineer
 
Join Date: May 2002
Rookie Year: 2001
Location: Redwood City, CA
Posts: 6,948
Cory has a reputation beyond reputeCory has a reputation beyond reputeCory has a reputation beyond reputeCory has a reputation beyond reputeCory has a reputation beyond reputeCory has a reputation beyond reputeCory has a reputation beyond reputeCory has a reputation beyond reputeCory has a reputation beyond reputeCory has a reputation beyond reputeCory has a reputation beyond repute
Re: Team 254 Presents: 2017 Misfire Technical Binder and Build Blogs

Quote:
Originally Posted by juju_beans View Post
Not 254, but my team also used #25 chain for our drive train without tensioners. We used the the exact c-c length + 3 thou, which we found using this calculator. Over the season the chain did start to loosen up and sag a tiny bit, but since we used chain-in-tube, the chain wouldn't be able to fall off. As for how long they lasted, both our practice and our competition bot still have their original chains. For machining tolerances, they really weren't anything special especially since all of my team's metal working is done on a cheap mini mill with a DRO.
.003 is nowhere near enough in our experience. Paul Copioli has a tool somewhere (I think in a presentation he made) that we used as a starting point and then did empirical testing of additional added distance.

We used +.018" on a 10.75" C-C run (very close, if not exactly what Paul recommended) and +.030" on a 20.75" C-C run.
__________________
2001-2004: Team 100
2006-Present: Team 254
Reply With Quote
  #35   Spotlight this post!  
Unread 09-13-2017, 09:38 AM
Ty Tremblay's Avatar
Ty Tremblay Ty Tremblay is offline
Robotics Engineer
FRC #0319 (Big Bad Bob)
Team Role: Mentor
 
Join Date: Feb 2006
Rookie Year: 2004
Location: Alton NH
Posts: 945
Ty Tremblay has a reputation beyond reputeTy Tremblay has a reputation beyond reputeTy Tremblay has a reputation beyond reputeTy Tremblay has a reputation beyond reputeTy Tremblay has a reputation beyond reputeTy Tremblay has a reputation beyond reputeTy Tremblay has a reputation beyond reputeTy Tremblay has a reputation beyond reputeTy Tremblay has a reputation beyond reputeTy Tremblay has a reputation beyond reputeTy Tremblay has a reputation beyond repute
Re: Team 254 Presents: 2017 Misfire Technical Binder and Build Blogs

Quote:
Originally Posted by Cory View Post
.003 is nowhere near enough in our experience. Paul Copioli has a tool somewhere (I think in a presentation he made) that we used as a starting point and then did empirical testing of additional added distance.

We used +.018" on a 10.75" C-C run (very close, if not exactly what Paul recommended) and +.030" on a 20.75" C-C run.
I'll second the empirical approach. We found that chains from different manufacturers will require different additional c-c for the same run. (Vex heavy duty #25 vs McMaster #25 for example).
__________________
Reply With Quote
  #36   Spotlight this post!  
Unread 09-13-2017, 09:42 AM
Nate Laverdure's Avatar
Nate Laverdure Nate Laverdure is online now
Cynicism isn't wisdom
FRC #2363
Team Role: Coach
 
Join Date: Apr 2005
Rookie Year: 1999
Location: Newport News, VA
Posts: 910
Nate Laverdure has a reputation beyond reputeNate Laverdure has a reputation beyond reputeNate Laverdure has a reputation beyond reputeNate Laverdure has a reputation beyond reputeNate Laverdure has a reputation beyond reputeNate Laverdure has a reputation beyond reputeNate Laverdure has a reputation beyond reputeNate Laverdure has a reputation beyond reputeNate Laverdure has a reputation beyond reputeNate Laverdure has a reputation beyond reputeNate Laverdure has a reputation beyond repute
Re: Team 254 Presents: 2017 Misfire Technical Binder and Build Blogs

Quote:
Originally Posted by Ty Tremblay View Post
I'll second the empirical approach. We found that chains from different manufacturers will require different additional c-c for the same run. (Vex heavy duty #25 vs McMaster #25 for example).
Thirded. We found that even chain from the same vendor, but purchased at different times, will require different additional c-c for the same run.
Reply With Quote
  #37   Spotlight this post!  
Unread 09-13-2017, 10:07 AM
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: 799
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: Team 254 Presents: 2017 Misfire Technical Binder and Build Blogs

Quote:
Originally Posted by Cory View Post
.003 is nowhere near enough in our experience. Paul Copioli has a tool somewhere (I think in a presentation he made) that we used as a starting point and then did empirical testing of additional added distance.

We used +.018" on a 10.75" C-C run (very close, if not exactly what Paul recommended) and +.030" on a 20.75" C-C run.
Quote:
Originally Posted by Ty Tremblay View Post
I'll second the empirical approach. We found that chains from different manufacturers will require different additional c-c for the same run. (Vex heavy duty #25 vs McMaster #25 for example).
Quote:
Originally Posted by Nate Laverdure View Post
Thirded. We found that even chain from the same vendor, but purchased at different times, will require different additional c-c for the same run.
Mind sharing your teams' methods of empirically determining addendum distance? It's a bit of a tangent and possibly deserving of its own thread, but I'd appreciate a quick run through.
__________________
"It's taking longer than expected, which was to be expected."
Reply With Quote
  #38   Spotlight this post!  
Unread 09-13-2017, 10:20 AM
Nate Laverdure's Avatar
Nate Laverdure Nate Laverdure is online now
Cynicism isn't wisdom
FRC #2363
Team Role: Coach
 
Join Date: Apr 2005
Rookie Year: 1999
Location: Newport News, VA
Posts: 910
Nate Laverdure has a reputation beyond reputeNate Laverdure has a reputation beyond reputeNate Laverdure has a reputation beyond reputeNate Laverdure has a reputation beyond reputeNate Laverdure has a reputation beyond reputeNate Laverdure has a reputation beyond reputeNate Laverdure has a reputation beyond reputeNate Laverdure has a reputation beyond reputeNate Laverdure has a reputation beyond reputeNate Laverdure has a reputation beyond reputeNate Laverdure has a reputation beyond repute
Re: Team 254 Presents: 2017 Misfire Technical Binder and Build Blogs

Quote:
Originally Posted by Cothron Theiss View Post
Mind sharing your teams' methods of empirically determining addendum distance? It's a bit of a tangent and possibly deserving of its own thread, but I'd appreciate a quick run through.
Here you go!
Quote:
Originally Posted by ToddF View Post
This summer we are experimenting with non-adjustable wheel positions, and chains inside our side rails.

The first rail we made had nominal C2C distances. While it is functional, the chains sag enough to touch the inside of the rail tube, making the drive assembly noisy when running. For the second tube, we took a WAG (embarrassing to admit, for engineers), and increased the C2C distance about .008". This resulted in saggy chains again. After that, we did what we should have done from the start, and actually measured the C2C distance of tensioned chains, instead of just guessing.

We made this test setup, first using the chain from our experimental drive train, with a nominal C2C distance of 10.75". Note that the sprockets, bearings and shafting are all 1/2" hex type, all from VEXpro. There are slip fit tolerances between these parts that require the C2C distance of the bearing pockets to be greater than nominal to achieve a tight chain. Also note that the neither the hex holes in the bearings nor the hex holes in the sprockets are truly concentric. This leads to visible wobble in the OD of the sprockets, when they spin. This causes the chain tension to vary, and is a source of vibration and cyclic fatigue to the overall drivetrain.



To test whether any C2C variations were related to the length of the chain, we also tested a nominal 4" C2C chain setup.



The chain tension was set by anchoring one of the bearing blocks, pulling the chain "finger tight" and locking down the other bearing block. We then spun the chain by hand to observe that it could run free, and hand checked the chain tension the same way we do in the pits, to be sure it was tensioned comparably to our competition drive trains. Then we removed the chains, sprockets, shafts, and upper bearings. The upper bearings have a tight slip fit. To remove them, it was necessary to insert the end of an axle shaft and wiggle it around, working the bearing loose. This left the two bearing blocks with the bearing pockets exposed.



We then used the milling machine edge finder and the dimensional readout to find the C2C distances (we actually measured to the left sides of both bearing pockets).

Here are the results:


We concluded that the increase in C2C distance was due to the tolerance stackup of the parts, and not tightly related to the length of the chains. We plan to incorporate a .019" to .020" delta to our nominal C2C distances in future designs.
Reply With Quote
  #39   Spotlight this post!  
Unread 09-13-2017, 10:37 AM
JesseK's Avatar
JesseK JesseK is offline
Expert Flybot Crasher
FRC #1885 (ILITE)
Team Role: Mentor
 
Join Date: Mar 2007
Rookie Year: 2005
Location: Reston, VA
Posts: 3,955
JesseK has a reputation beyond reputeJesseK has a reputation beyond reputeJesseK has a reputation beyond reputeJesseK has a reputation beyond reputeJesseK has a reputation beyond reputeJesseK has a reputation beyond reputeJesseK has a reputation beyond reputeJesseK has a reputation beyond reputeJesseK has a reputation beyond reputeJesseK has a reputation beyond reputeJesseK has a reputation beyond repute
Re: Team 254 Presents: 2017 Misfire Technical Binder and Build Blogs

I heard from a student at WCMP that current draw while shooting was a large concern. How bad was it, and what adjustments were made?

What, if any, fine-tuning needed to be made after importing from the Cheesy-path app? During refinement, was the default strategy to re-tune the path in the app, or re-calibrate sensors (etc) to get the actual path to match the desired path? What margin of precision was "good enough" for the gear + hopper auton?

Edit - Also, was it seen as a risk that a drive train CIM would be hit, given how close (or over?) the edge of the angled frame it is?
__________________

Drive Coach, 1885 (2007-present)
Latest Project: Codex-based FRC Comms in Java

2017: Scoring Model | COPR Rank Simulator
1885: YouTube Channel | CAD Library | GitHub

Last edited by JesseK : 09-13-2017 at 10:41 AM.
Reply With Quote
  #40   Spotlight this post!  
Unread 09-13-2017, 11:50 AM
Ty Tremblay's Avatar
Ty Tremblay Ty Tremblay is offline
Robotics Engineer
FRC #0319 (Big Bad Bob)
Team Role: Mentor
 
Join Date: Feb 2006
Rookie Year: 2004
Location: Alton NH
Posts: 945
Ty Tremblay has a reputation beyond reputeTy Tremblay has a reputation beyond reputeTy Tremblay has a reputation beyond reputeTy Tremblay has a reputation beyond reputeTy Tremblay has a reputation beyond reputeTy Tremblay has a reputation beyond reputeTy Tremblay has a reputation beyond reputeTy Tremblay has a reputation beyond reputeTy Tremblay has a reputation beyond reputeTy Tremblay has a reputation beyond reputeTy Tremblay has a reputation beyond repute
Re: Team 254 Presents: 2017 Misfire Technical Binder and Build Blogs

Quote:
Originally Posted by Cothron Theiss View Post
Mind sharing your teams' methods of empirically determining addendum distance? It's a bit of a tangent and possibly deserving of its own thread, but I'd appreciate a quick run through.
Quote:
Originally Posted by Nate Laverdure View Post
Here you go!
Ours is a modified method from 2363's post above. We milled the bearing holes in a 2x1 tube, then cut the tube in the middle. Then we assembled the chain on, pulled the two pieces apart, tightened the vice, and measured.

__________________
Reply With Quote
  #41   Spotlight this post!  
Unread 09-13-2017, 01:14 PM
Cory's Avatar
Cory Cory is offline
Registered User
AKA: Cory McBride
FRC #0254 (The Cheesy Poofs)
Team Role: Engineer
 
Join Date: May 2002
Rookie Year: 2001
Location: Redwood City, CA
Posts: 6,948
Cory has a reputation beyond reputeCory has a reputation beyond reputeCory has a reputation beyond reputeCory has a reputation beyond reputeCory has a reputation beyond reputeCory has a reputation beyond reputeCory has a reputation beyond reputeCory has a reputation beyond reputeCory has a reputation beyond reputeCory has a reputation beyond reputeCory has a reputation beyond repute
Re: Team 254 Presents: 2017 Misfire Technical Binder and Build Blogs

Quote:
Originally Posted by Cothron Theiss View Post
Mind sharing your teams' methods of empirically determining addendum distance? It's a bit of a tangent and possibly deserving of its own thread, but I'd appreciate a quick run through.
Nothing fancy here. Machined test rails with bearing bores at .005" increments and picked the one that felt best.
__________________
2001-2004: Team 100
2006-Present: Team 254
Reply With Quote
  #42   Spotlight this post!  
Unread 09-13-2017, 01:50 PM
Rafi Ahmed's Avatar
Rafi Ahmed Rafi Ahmed is offline
Mentor & Alumni
FRC #2522 (Royal Robotics)
Team Role: Mentor
 
Join Date: Mar 2005
Rookie Year: 2002
Location: Seattle
Posts: 204
Rafi Ahmed has a spectacular aura aboutRafi Ahmed has a spectacular aura about
Re: Team 254 Presents: 2017 Misfire Technical Binder and Build Blogs

Quote:
Originally Posted by Cory View Post
Nothing fancy here. Machined test rails with bearing bores at .005" increments and picked the one that felt best.
Was 25 chain used? Did you have any chain skipping or had to swap it out in the middle of the season?
__________________
Team 2522 | Mentor
Formerly of Team 22 and Team 4
Reply With Quote
  #43   Spotlight this post!  
Unread 09-13-2017, 02:39 PM
Cory's Avatar
Cory Cory is offline
Registered User
AKA: Cory McBride
FRC #0254 (The Cheesy Poofs)
Team Role: Engineer
 
Join Date: May 2002
Rookie Year: 2001
Location: Redwood City, CA
Posts: 6,948
Cory has a reputation beyond reputeCory has a reputation beyond reputeCory has a reputation beyond reputeCory has a reputation beyond reputeCory has a reputation beyond reputeCory has a reputation beyond reputeCory has a reputation beyond reputeCory has a reputation beyond reputeCory has a reputation beyond reputeCory has a reputation beyond reputeCory has a reputation beyond repute
Re: Team 254 Presents: 2017 Misfire Technical Binder and Build Blogs

Quote:
Originally Posted by Rafi Ahmed View Post
Was 25 chain used? Did you have any chain skipping or had to swap it out in the middle of the season?
#25 chain, no issues.
__________________
2001-2004: Team 100
2006-Present: Team 254
Reply With Quote
  #44   Spotlight this post!  
Unread 09-13-2017, 04:47 PM
Lil' Lavery Lil' Lavery is online now
TSIMFD
AKA: Sean Lavery
FRC #1712 (DAWGMA)
Team Role: Mentor
 
Join Date: Nov 2003
Rookie Year: 2003
Location: Philadelphia, PA
Posts: 7,044
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: Team 254 Presents: 2017 Misfire Technical Binder and Build Blogs

Was the initial effort of empirically determining C-C distance for individual chain runs worth it compared to adding some sort of adjustable tensioning device?
__________________
Being correct doesn't mean you don't have to explain yourself.
Reply With Quote
  #45   Spotlight this post!  
Unread 09-13-2017, 05:33 PM
Cory's Avatar
Cory Cory is offline
Registered User
AKA: Cory McBride
FRC #0254 (The Cheesy Poofs)
Team Role: Engineer
 
Join Date: May 2002
Rookie Year: 2001
Location: Redwood City, CA
Posts: 6,948
Cory has a reputation beyond reputeCory has a reputation beyond reputeCory has a reputation beyond reputeCory has a reputation beyond reputeCory has a reputation beyond reputeCory has a reputation beyond reputeCory has a reputation beyond reputeCory has a reputation beyond reputeCory has a reputation beyond reputeCory has a reputation beyond reputeCory has a reputation beyond repute
Re: Team 254 Presents: 2017 Misfire Technical Binder and Build Blogs

Quote:
Originally Posted by Lil' Lavery View Post
Was the initial effort of empirically determining C-C distance for individual chain runs worth it compared to adding some sort of adjustable tensioning device?
It was 20 minutes of CAM/CNC time and saved us making 3 days worth of parts, so 100% worth it.
__________________
2001-2004: Team 100
2006-Present: Team 254
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 05:32 PM.

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