Go to Post Nats allows an exchange of a vast multitude of ideas from everywhere. Not only in robot design, but accents, tool storage, pit design, team spirt, clothing, many things. - Wetzel [more]
Home
Go Back   Chief Delphi > Technical > Programming
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
  #46   Spotlight this post!  
Unread 07-01-2009, 23:06
keehun's Avatar
keehun keehun is offline
Team Captain
AKA: Keehun Nam
FRC #2502 (EP Robotics)
Team Role: Leadership
 
Join Date: May 2008
Rookie Year: 2008
Location: Eden Priaire
Posts: 474
keehun has a reputation beyond reputekeehun has a reputation beyond reputekeehun has a reputation beyond reputekeehun has a reputation beyond reputekeehun has a reputation beyond reputekeehun has a reputation beyond reputekeehun has a reputation beyond reputekeehun has a reputation beyond reputekeehun has a reputation beyond reputekeehun has a reputation beyond reputekeehun has a reputation beyond repute
Send a message via AIM to keehun
Re: Implementing Traction Control for an advantage in the 2009 game

Quote:
Originally Posted by DadDean View Post
I think this game is going to fun to build, play, and watch
Do you mean: "I think this game is going to be fun to build, frustrating to play, and funniest to watch"

;-)
__________________
For by grace you have been saved through faith, and that not of yourselves; it is the gift of God, not of works, lest anyone should boast. -- Ephesians 2:8-9
2010: Quarter Finalist (MN 10,000 Lakes)
2010: Website Award (MN 10,000 Lakes)
2009: Quarter Finalist (MN 10,000 Lakes)
2009: GM Industrial Award (MN 10,000 Lakes)
  #47   Spotlight this post!  
Unread 08-01-2009, 01:08
DavidGitz's Avatar
DavidGitz DavidGitz is offline
Lead Technical Advisor
FRC #1208 (MeTool Brigade)
Team Role: Coach
 
Join Date: Dec 2006
Rookie Year: 1996
Location: O'Fallon, IL
Posts: 341
DavidGitz has much to be proud ofDavidGitz has much to be proud ofDavidGitz has much to be proud ofDavidGitz has much to be proud ofDavidGitz has much to be proud ofDavidGitz has much to be proud ofDavidGitz has much to be proud ofDavidGitz has much to be proud of
Send a message via AIM to DavidGitz Send a message via MSN to DavidGitz Send a message via Yahoo to DavidGitz
Re: Implementing Traction Control for an advantage in the 2009 game

Quote:
Originally Posted by Abwehr View Post
3b. Even in a 4WD robot with 4 independently-powered wheels with encoders, you can detect (some kinds of) slip without the need for additional sensors. You know where on your robot the wheels are mounted. You can measure the speeds of all four wheels. If you examine the speeds of three wheels at a time, you can compute what the speed of the fourth you HAVE to be in order for there to be no slippage. You can do this for all 4 combinations of three wheels and deduce which wheel(s) are lying to you. If all four (or even three, and sometimes two) wheels are slipping, you're still out of luck, but if one wheel loses traction before the others, you will know.
So far this is pretty much exactly what we are doing, but we have a couple other methods too, like an E-Brake that senses the direction of the angle that you are drifting at and when enabled (a joystick button) turns our wheels perpendicular to the drift angle. You wouldn't have much control during the braking but it might help some. We will post our results when available.

Last edited by DavidGitz : 08-01-2009 at 01:08. Reason: bad code
  #48   Spotlight this post!  
Unread 08-01-2009, 07:38
windell747 windell747 is offline
Registered User
FRC #2477
Team Role: Mentor
 
Join Date: Jan 2008
Rookie Year: 2001
Location: Hawaii
Posts: 158
windell747 will become famous soon enoughwindell747 will become famous soon enough
Re: Implementing Traction Control for an advantage in the 2009 game

Although this might be overly complex, something out of the box would be to create some sort of velocimeter that bounces sound off the ground and measures the change in reflected frequency due to the sound doppler shift. Ocean current profilers work in this fashion. Of course an encoder can accomplish the same thing, in a simler fashion, but just wanted to throw the idea out there.

I like the idea brought up earlier about monitoring the motor's current to detect a drop in load due to the transition from static to kinetic friction.
  #49   Spotlight this post!  
Unread 08-01-2009, 08:31
XXShadowXX's Avatar
XXShadowXX XXShadowXX is offline
They call me Cody.
no team (None currently :\)
Team Role: Mentor
 
Join Date: Jan 2008
Rookie Year: 2008
Location: Pontiac; MI
Posts: 408
XXShadowXX has much to be proud ofXXShadowXX has much to be proud ofXXShadowXX has much to be proud ofXXShadowXX has much to be proud ofXXShadowXX has much to be proud ofXXShadowXX has much to be proud ofXXShadowXX has much to be proud ofXXShadowXX has much to be proud ofXXShadowXX has much to be proud ofXXShadowXX has much to be proud of
Re: Implementing Traction Control for an advantage in the 2009 game

Some one might have posted this, but if you use the accelerometer to measure the acceleration of the robot, and solve for what your acceleration should be if the limit of the wheels speed is approaching the speed of the robot, to achieve maximum traction you can multiply the forward force by 120%! Of course you need some serious math for this, but nearly three quarters of it will be math, so if you can solve the math you should be able to program it.
__________________
Is now an engineer thanks to FIRST.
  #50   Spotlight this post!  
Unread 08-01-2009, 09:56
purduephotog purduephotog is offline
Active Defense Design Engineer
AKA: Jason
FRC #3015
Team Role: Leadership
 
Join Date: Jan 2007
Rookie Year: 2004
Location: Rochester, NY
Posts: 162
purduephotog is a jewel in the roughpurduephotog is a jewel in the roughpurduephotog is a jewel in the roughpurduephotog is a jewel in the rough
Send a message via AIM to purduephotog
Re: Implementing Traction Control for an advantage in the 2009 game

Quote:
Originally Posted by windell747 View Post
Although this might be overly complex, something out of the box would be to create some sort of velocimeter that bounces sound off the ground and measures the change in reflected frequency due to the sound doppler shift. Ocean current profilers work in this fashion. Of course an encoder can accomplish the same thing, in a similar fashion, but just wanted to throw the idea out there.

I like the idea brought up earlier about monitoring the motor's current to detect a drop in load due to the transition from static to kinetic friction.
http://cigr-ejournal.tamu.edu/submis...2001%20007.pdf

Ocean current profilers are called sounders, I think? Check out how the weather satellites do it if you're really interested.
__________________
http://purduephotog.deviantart.com
Portrait Photography: "I used to say Immortalized in Silver, but now I say Captured and Squeezed by Electrons".
  #51   Spotlight this post!  
Unread 08-01-2009, 10:26
EricVanWyk EricVanWyk is offline
Registered User
no team
 
Join Date: Jan 2007
Rookie Year: 2000
Location: Boston
Posts: 1,597
EricVanWyk has a reputation beyond reputeEricVanWyk has a reputation beyond reputeEricVanWyk has a reputation beyond reputeEricVanWyk has a reputation beyond reputeEricVanWyk has a reputation beyond reputeEricVanWyk has a reputation beyond reputeEricVanWyk has a reputation beyond reputeEricVanWyk has a reputation beyond reputeEricVanWyk has a reputation beyond reputeEricVanWyk has a reputation beyond reputeEricVanWyk has a reputation beyond repute
Send a message via AIM to EricVanWyk
Re: Implementing Traction Control for an advantage in the 2009 game

windell747 & purduephotog -

Very cool! That is essentially a radar gun using sound instead of RF. That got me thinking - why not use a radar gun?

Do you know of any vendors that sell an accoustic radar gun?
  #52   Spotlight this post!  
Unread 08-01-2009, 10:32
Dave Flowerday Dave Flowerday is offline
Software Engineer
VRC #0111 (Wildstang)
Team Role: Engineer
 
Join Date: Feb 2002
Rookie Year: 1995
Location: North Barrington, IL
Posts: 1,366
Dave Flowerday has a reputation beyond reputeDave Flowerday has a reputation beyond reputeDave Flowerday has a reputation beyond reputeDave Flowerday has a reputation beyond reputeDave Flowerday has a reputation beyond reputeDave Flowerday has a reputation beyond reputeDave Flowerday has a reputation beyond reputeDave Flowerday has a reputation beyond reputeDave Flowerday has a reputation beyond reputeDave Flowerday has a reputation beyond reputeDave Flowerday has a reputation beyond repute
Re: Implementing Traction Control for an advantage in the 2009 game

Quote:
Originally Posted by EricVanWyk View Post
That got me thinking - why not use a radar gun?
I thought of that earlier, but I assume the GDC would take issue with me sticking a 10GHz transmitter on my robot. Then again, the rules as worded don't really address it - they only discuss wireless communication. But, I think the intent is clear - no RF transmitters or receivers on the robot other than the wireless bridge.
  #53   Spotlight this post!  
Unread 08-01-2009, 10:52
IKE's Avatar
IKE IKE is offline
Not so Custom User Title
AKA: Isaac Rife
no team (N/A)
Team Role: Mechanical
 
Join Date: Jan 2008
Rookie Year: 2003
Location: Michigan
Posts: 2,153
IKE has a reputation beyond reputeIKE has a reputation beyond reputeIKE has a reputation beyond reputeIKE has a reputation beyond reputeIKE has a reputation beyond reputeIKE has a reputation beyond reputeIKE has a reputation beyond reputeIKE has a reputation beyond reputeIKE has a reputation beyond reputeIKE has a reputation beyond reputeIKE has a reputation beyond repute
Re: Implementing Traction Control for an advantage in the 2009 game

I know that for braking and acceleration testing at Chrysler we had an optical 5th wheel device that I believe used laser system similar to an optical mouse just with better range. I think these are pretty expensive, and the ones I found online are heavy (0.5Kg for sensor and 1Kg for single converter).

If anyone finds an optical mouse that reads the surface well without touching it, I would love to know the model!
  #54   Spotlight this post!  
Unread 08-01-2009, 10:57
Clinton Bolinger's Avatar
Clinton Bolinger Clinton Bolinger is offline
FF - PureMichigan
FRC #2337 (EngiNERDs)
Team Role: Coach
 
Join Date: Dec 2006
Rookie Year: 2001
Location: Grand Blanc, MI
Posts: 476
Clinton Bolinger has a reputation beyond reputeClinton Bolinger has a reputation beyond reputeClinton Bolinger has a reputation beyond reputeClinton Bolinger has a reputation beyond reputeClinton Bolinger has a reputation beyond reputeClinton Bolinger has a reputation beyond reputeClinton Bolinger has a reputation beyond reputeClinton Bolinger has a reputation beyond reputeClinton Bolinger has a reputation beyond reputeClinton Bolinger has a reputation beyond reputeClinton Bolinger has a reputation beyond repute
Re: Implementing Traction Control for an advantage in the 2009 game

If your Coefficient of Friction of the mouse is less than the Rover Wheels would that be expectable because it does not increase your traction and you are using it for input rather then output?

-Oris-
__________________
  #55   Spotlight this post!  
Unread 08-01-2009, 10:58
IKE's Avatar
IKE IKE is offline
Not so Custom User Title
AKA: Isaac Rife
no team (N/A)
Team Role: Mechanical
 
Join Date: Jan 2008
Rookie Year: 2003
Location: Michigan
Posts: 2,153
IKE has a reputation beyond reputeIKE has a reputation beyond reputeIKE has a reputation beyond reputeIKE has a reputation beyond reputeIKE has a reputation beyond reputeIKE has a reputation beyond reputeIKE has a reputation beyond reputeIKE has a reputation beyond reputeIKE has a reputation beyond reputeIKE has a reputation beyond reputeIKE has a reputation beyond repute
Re: Implementing Traction Control for an advantage in the 2009 game

Quote:
Originally Posted by Paul Copioli View Post
To answer the earlier question, what we do on carpet is use an idler wheel on a spring connected to an encoder. this will not really take away from normal force (very, very small spring load) but we are concerned this year that we have to use the actual wheel instead of a small wheel and that the low friction will make that one slip too.
I think that we are going to ask in the Official Q&A if a small caster with no motive force, and no way of providing traction can be used to get surface speed and direction, but I am fairly certain they will give a resounding "NO".
  #56   Spotlight this post!  
Unread 08-01-2009, 11:05
Tom Bottiglieri Tom Bottiglieri is offline
Registered User
FRC #0254 (The Cheesy Poofs)
Team Role: Engineer
 
Join Date: Jan 2004
Rookie Year: 2003
Location: San Francisco, CA
Posts: 3,189
Tom Bottiglieri has a reputation beyond reputeTom Bottiglieri has a reputation beyond reputeTom Bottiglieri has a reputation beyond reputeTom Bottiglieri has a reputation beyond reputeTom Bottiglieri has a reputation beyond reputeTom Bottiglieri has a reputation beyond reputeTom Bottiglieri has a reputation beyond reputeTom Bottiglieri has a reputation beyond reputeTom Bottiglieri has a reputation beyond reputeTom Bottiglieri has a reputation beyond reputeTom Bottiglieri has a reputation beyond repute
Re: Implementing Traction Control for an advantage in the 2009 game

Has anyone thought about using an FIR filter on joystick inputs? It would work for acceleration from a stop in either direction (F/R), but I am stuck on how change directions or stop without considerable lag.

Thoughts?

Last edited by Tom Bottiglieri : 08-01-2009 at 11:09.
  #57   Spotlight this post!  
Unread 08-01-2009, 11:05
Clinton Bolinger's Avatar
Clinton Bolinger Clinton Bolinger is offline
FF - PureMichigan
FRC #2337 (EngiNERDs)
Team Role: Coach
 
Join Date: Dec 2006
Rookie Year: 2001
Location: Grand Blanc, MI
Posts: 476
Clinton Bolinger has a reputation beyond reputeClinton Bolinger has a reputation beyond reputeClinton Bolinger has a reputation beyond reputeClinton Bolinger has a reputation beyond reputeClinton Bolinger has a reputation beyond reputeClinton Bolinger has a reputation beyond reputeClinton Bolinger has a reputation beyond reputeClinton Bolinger has a reputation beyond reputeClinton Bolinger has a reputation beyond reputeClinton Bolinger has a reputation beyond reputeClinton Bolinger has a reputation beyond repute
Re: Implementing Traction Control for an advantage in the 2009 game

Just make the wheel of the caster a Rover Wheel.

-Oris-
__________________
  #58   Spotlight this post!  
Unread 08-01-2009, 11:28
Madison's Avatar
Madison Madison is offline
Dancing through life...
FRC #0488 (Xbot)
Team Role: Engineer
 
Join Date: Jun 2001
Rookie Year: 1999
Location: Seattle, WA
Posts: 5,245
Madison has a reputation beyond reputeMadison has a reputation beyond reputeMadison has a reputation beyond reputeMadison has a reputation beyond reputeMadison has a reputation beyond reputeMadison has a reputation beyond reputeMadison has a reputation beyond reputeMadison has a reputation beyond reputeMadison has a reputation beyond reputeMadison has a reputation beyond reputeMadison has a reputation beyond repute
Re: Implementing Traction Control for an advantage in the 2009 game

Quote:
Originally Posted by IKE View Post
I think that we are going to ask in the Official Q&A if a small caster with no motive force, and no way of providing traction can be used to get surface speed and direction, but I am fairly certain they will give a resounding "NO".
One of the first responses on the Q&A system indicates that this is legal.

http://forums.usfirst.org/showthread.php?t=10917
__________________
--Madison--

...down at the Ozdust!

Like a grand and miraculous spaceship, our planet has sailed through the universe of time. And for a brief moment, we have been among its many passengers.
  #59   Spotlight this post!  
Unread 08-01-2009, 11:33
Unsung FIRST Hero
Warren Boudreau Warren Boudreau is offline
Registered User
FRC #0180 (Team SPAM)
Team Role: Mentor
 
Join Date: Jan 2002
Rookie Year: 1999
Location: Stuart, FL
Posts: 354
Warren Boudreau has a reputation beyond reputeWarren Boudreau has a reputation beyond reputeWarren Boudreau has a reputation beyond reputeWarren Boudreau has a reputation beyond reputeWarren Boudreau has a reputation beyond reputeWarren Boudreau has a reputation beyond reputeWarren Boudreau has a reputation beyond reputeWarren Boudreau has a reputation beyond reputeWarren Boudreau has a reputation beyond reputeWarren Boudreau has a reputation beyond reputeWarren Boudreau has a reputation beyond repute
Re: Implementing Traction Control for an advantage in the 2009 game

First, I want to thank everyone for such a wonderful open flow of information on this topic. This is such a tremendous paradigm shift from previous years that teams could fall into a "Cold War" mentality and not share this information with others.

Now, Paul Coplioi's post on the second page made one assumption that I thought I would try to correct.

I don't think that the mass cancels out in the equation for maximum acceleration (amax=g*CoF). If you walk through it carefully, you will see that while the friction force is Cof*robot weight, the mass that you are acceleating includes the trailer weight. In that case, the maximum acceleration of the system will be limited to roughly 75% of g*CoF.

This should only affect teams who are measuring acceleration. Teams using encoders and follower wheels (thank you FIRST GDC for the rapid response to that question) should not see a problem.
__________________
Warren B

Pool Noodles. They're not just for bumpers anymore.
  #60   Spotlight this post!  
Unread 08-01-2009, 13:03
Justin Stiltner's Avatar
Justin Stiltner Justin Stiltner is offline
The big guy
no team
Team Role: Engineer
 
Join Date: Jun 2001
Rookie Year: 2000
Location: Blacksburg, Va.
Posts: 305
Justin Stiltner has much to be proud ofJustin Stiltner has much to be proud ofJustin Stiltner has much to be proud ofJustin Stiltner has much to be proud ofJustin Stiltner has much to be proud ofJustin Stiltner has much to be proud ofJustin Stiltner has much to be proud ofJustin Stiltner has much to be proud ofJustin Stiltner has much to be proud ofJustin Stiltner has much to be proud of
Send a message via ICQ to Justin Stiltner Send a message via AIM to Justin Stiltner Send a message via MSN to Justin Stiltner Send a message via Yahoo to Justin Stiltner
Re: Implementing Traction Control for an advantage in the 2009 game

With the recent allowing of idler wheels this will probably not be needed but my thought was to have a pivoting motor mount with a load cell under one of the mounts, thus you could sense the torque applied to the motor shaft. you should be able to calculate, and after it is done test to find your maximum torque that can be applied before slippage occurs, then write your software to drive the motor to this condition. In this case, if you diden't use speed input (would be a good idea to do so) your joystick would become not a speed input, but a torque input, or just like the accelerator pedal in your car!

But the sensor wheel will most likely give you 95% of the benefit that you are looking for anyway, but I like to throw my ideas out there and see if anyone bites.
__________________
Justin Stiltner
Lead Robot Inspector, VCU Regional
Unmanned Systems Lab, Virginia Tech
KI4URQ
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
The 2009 Control System Q&A Thread crake FRC Control System 59 11-01-2009 10:43
Drive train for 2009 game hihihiflcl81pig General Forum 4 27-12-2008 02:17
Buying the 2009 control system BornaE FRC Control System 9 16-10-2008 17:16
The Access Points on the 2009 Control System Shadow503 Rumor Mill 10 28-04-2008 23:22
UNFAIR ADVANTAGE for CDI and new control system archiver 2000 6 23-06-2002 22:13


All times are GMT -5. The time now is 13:32.

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