Chief Delphi paper: Shooter Wheel Speed Control
 CD-Media CD-Spy
 portal register members calendar search Today's Posts Mark Forums Read FAQ rules

#21
04-17-2012, 06:26 PM
 billbo911 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: 2,625
Re: paper: Shooter Wheel Speed Control

Quote:
 Originally Posted by Ether I should have been clearer: The "low_command" is a tuning constant, not the target speed, and was not intended to be so low that it tops out at a speed below the "spinup_speed". "low_command" should be high enough that it briskly accelerates up to (and beyond) spinup_speed, at which point the full voltage is applied. Many shooter wheel setups can handle application of full voltage to the motor even at zero RPM, but some can't. It's a function of the gear ratio and the wheel inertia and the motor being used. For such setups, simply set spinup_speed=0.0 The code I posted was for those shooter setups that can't handle a full 12 volts being applied at zero RPM, but could, for example, handle, say, 8 volts at zero RPM and 12 volts at 1000 RPM. For that example, you would set spinup_speed to 1000 RPM and low_command to 8 volts. Simple, and gets the job done. With the code I posted, the minimum continuous RPM is simply commanded as the target speed by each team's software to whatever they want it to be, and the code I posted will bang-bang regulate at that speed. That target speed can be zero if the team so desires. For really finicky setups (e.g. high inertia wheel, not much gear ratio), you could always add a third "else" statement: Code: ```if (measured_speed >= target_speed) motor_command = 0.0; else if (measured_speed >= spinup_speed) motor_command = 1.0; else if (measured_speed >= medium_speed) motor_command = medium_command; else motor_command = low_command;```
Got it. So, in essence, you want the absolute maximum acceleration possible, for the particular shooter design, that it can handle without tripping the over-current.

With the version I added today, you can set the trip point for low to high acceleration as well as the rate of slew rate limiter. By tuning these two, you can achieve almost exactly what you are describing. The only difference is the start up voltage will be a ramp, with an adjustable slope, instead of a step from 0v. Granted, it is not the absolute fastest acceleration you can get, but I doubt the differences will be noticeable in actual performance. You will see it on a scope, but that's pretty much it. I'm guessing a only few millisecond difference between the two designs from 0 RPM to target RPM in the 2500-4000 range.
__________________
CalGames 2009 Autonomous Champion 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
2017 Utah Regional Winner!, Sacramento Finalist
Innovation in Control Newton/Carver Divisions , Newton #5 Captain
2018 WFFA Sacramento, Creativity Award Galileo-Robling Divisions

 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 User Control Panel Private Messages Subscriptions Who's Online Search Forums Forums Home Announcements     User Announcements FIRST     General Forum         FIRST E-Mail Blast Archive     Rumor Mill     Career     Robot Showcase Technical     Technical Discussion     Robotics Education and Curriculum     Motors     Electrical         CAN     Programming         NI LabVIEW         C/C++         Java         Python     Control System         FRC Control System         Sensors     Pneumatics     Kit & Additional Hardware     CAD         Inventor         SolidWorks         Creo     IT / Communications         3D Animation and Competition         Website Design/Showcase         Videography and Photography         Computer Graphics     National Instruments LabVIEW and Data Acquisition         LabView and Data Acquisition Competition     Unsung FIRST Heroes     Awards         Chairman's Award     Rules/Strategy         Scouting         You Make The Call     Team Organization         Fundraising         Starting New Teams         Finding A Team         College Teams     Championship Event     Regional Competitions     District Events     Off-Season Events     Thanks and/or Congrats     FRC Game Design     OCCRA         OCCRA Q&A         OCCRA Programming Other     Chit-Chat         Games/Trivia             Fantasy FIRST     Car Nack's Corner     College & University Education     Dean Kamen's Inventions     FIRST-related Organizations         Western Region Robotics Forum         Southern California Regional Robotics Forum         The Blue Alliance             Video Archives     FIRST In the News...     FIRST Lego League         Lego Mindstorm Discussion     FIRST Tech Challenge     VEX         VEX Robotics Competition         VEX IQ     Televised Robotics     Math and Science         NASA Discussion ChiefDelphi.com Website     CD Forum Support     Extra Discussion

All times are GMT -5. The time now is 05:39 PM.

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

 -- English (12 hour) -- English (24 hour) Contact Us - Chief Delphi - Rules - Archive - Top