Thread: Tuning PID
View Single Post
  #5   Spotlight this post!  
Unread 22-01-2016, 22:40
GeeTwo's Avatar
GeeTwo GeeTwo is offline
Technical Director
AKA: Gus Michel II
FRC #3946 (Tiger Robotics)
Team Role: Mentor
 
Join Date: Jan 2014
Rookie Year: 2013
Location: Slidell, LA
Posts: 3,574
GeeTwo has a reputation beyond reputeGeeTwo has a reputation beyond reputeGeeTwo has a reputation beyond reputeGeeTwo has a reputation beyond reputeGeeTwo has a reputation beyond reputeGeeTwo has a reputation beyond reputeGeeTwo has a reputation beyond reputeGeeTwo has a reputation beyond reputeGeeTwo has a reputation beyond reputeGeeTwo has a reputation beyond reputeGeeTwo has a reputation beyond repute
Re: Tuning PID

Your initial problem is not that surprising. For an arm with a large angular displacement, the gravity torque is directed and proportional to the cosine of the arm's angle to the horizontal. This is going to give very different behavior up vs down. As stated above, tune P (and possibly I) so that the oscillation center is correct, then increase D to dampen the oscillations. P and I may require minor mods after increasing D, but probably not too severely.
__________________

If you can't find time to do it right, how are you going to find time to do it over?
If you don't pass it on, it never happened.
Robots are great, but inspiration is the reason we're here.
Friends don't let friends use master links.