View Single Post
  #11   Spotlight this post!  
Unread 07-04-2008, 10:09
billbo911's Avatar
billbo911 billbo911 is offline
I prefer you give a perfect effort.
AKA: That's "Mr. Bill"
FRC #2073 (EagleForce)
Team Role: Mentor
 
Join Date: Mar 2005
Rookie Year: 2005
Location: Elk Grove, Ca.
Posts: 2,358
billbo911 has a reputation beyond reputebillbo911 has a reputation beyond reputebillbo911 has a reputation beyond reputebillbo911 has a reputation beyond reputebillbo911 has a reputation beyond reputebillbo911 has a reputation beyond reputebillbo911 has a reputation beyond reputebillbo911 has a reputation beyond reputebillbo911 has a reputation beyond reputebillbo911 has a reputation beyond reputebillbo911 has a reputation beyond repute
Re: Accurately "Arcing" in Auton/Hybrid Mode

Quote:
Originally Posted by kiettyyyy View Post
In the case that your drivetrain has some type of inefficiency, ie: a motor going bad, etc. Couldn't your robot perform an arc with a wider or tighter turn radius than you commanded your robot to perform(without encoders or gear tooth sensors on both sides of your drivetrain)?
Yes, that is absolutely correct. We were basically doing "DEAD RECKONING". Any variation in the drivetrain or an impact from another robot could cause this entire process to fail.

Quote:
Originally Posted by kiettyyyy View Post
How do you go about countering this issue?
That is what I was referring to in the last part of my post. One reliable way for you to maintain your intended path, taking into account bumps and additional drag, would be to use feedback via encoders in your drivetrain, and your heading with a gyro.
Then when deviations occur from your intended path your robot could automatically respond to them.

As Jay Lundy suggests, it is possible to automatically make a U-turn of a known diameter with a Gyro.

An alternative would also take a little trial and error, but is fairly simple.
Set the inside wheel to a fixed PWM value. Then use a PID loop to control the outside wheel. The feedback you would use it the RATE out of the gyro, not the angle. Give the PID loop the rate you desire, it will then modify the output until the rate is achieved. Then all you have to do is determine what PWM value given to the inside wheel will produce the diameter turn you desire.
__________________
CalGames 2009 Autonomous Champion Award winner
Sacramento 2010 Creativity in Design winner, Sacramento 2010 Quarter finalist
2011 Sacramento Finalist, 2011 Madtown Engineering Inspiration Award.
2012 Sacramento Semi-Finals, 2012 Sacramento Innovation in Control Award, 2012 SVR Judges Award.
2012 CalGames Autonomous Challenge Award winner ($$$).
2014 2X Rockwell Automation: Innovation in Control Award (CVR and SAC). Curie Division Gracious Professionalism Award.
2014 Capital City Classic Winner AND Runner Up. Madtown Throwdown: Runner up.
2015 Innovation in Control Award, Sacramento.
2016 Chezy Champs Finalist, 2016 MTTD Finalist

Last edited by billbo911 : 07-04-2008 at 10:20.