Thread: speed issues
View Single Post
  #3   Spotlight this post!  
Unread 21-02-2016, 19:38
Joe Johnson's Avatar Unsung FIRST Hero
Joe Johnson Joe Johnson is offline
Engineer at Medrobotics
AKA: Dr. Joe
FRC #0088 (TJ2)
Team Role: Engineer
 
Join Date: May 2001
Rookie Year: 1996
Location: Raynham, MA
Posts: 2,644
Joe Johnson has a reputation beyond reputeJoe Johnson has a reputation beyond reputeJoe Johnson has a reputation beyond reputeJoe Johnson has a reputation beyond reputeJoe Johnson has a reputation beyond reputeJoe Johnson has a reputation beyond reputeJoe Johnson has a reputation beyond reputeJoe Johnson has a reputation beyond reputeJoe Johnson has a reputation beyond reputeJoe Johnson has a reputation beyond reputeJoe Johnson has a reputation beyond repute
Re: speed issues

Quote:
Originally Posted by cjl2625 View Post
Earlier in the season, we built a really rough prototype shooter, and it was going on and off when we tried running it at full speed. I checked the current readings on the CIM, and they were upwards of 50 amps when running at constant speed. The assembly was put together rather poorly, and it put a lot of strain on the motor, leading to these crazy high currents. I think the cylcling problem was something on the roborio periodically cutting power to the motor to prevent the high current.

Maybe you're facing a different issue, but perhaps you could try checking the current readings from the PDP, or remove the motor from the shooter and see if the speed still fluctuates.
Good points. Also you should consider if your shooter wheels are spoked wheels then they may be acting as a fan and that moving air is adding to your loading and possibly triggering current limiting events.

Dr. Joe J.
__________________
Joseph M. Johnson, Ph.D., P.E.
Mentor
Team #88, TJ2