View Single Post
  #3   Spotlight this post!  
Unread 28-02-2016, 15:02
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: 3,564
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: Encoder instability

How much do you lose the angle? Is it small enough just to be backlash, or is this really a significant amount?

Under what conditions does this happen/not happen? E.g. only when being backdriven, only in reverse, only when the last joystick command was x. Any patterns as to when it does/does not happen can help point to a cause.

Mechanically, if larger than a backlash value, i do not see how the problem could be inside the gearbox unless some teeth are practically missing or there's a similarly large failure. The coupling of the encoder to the backshaft is a possibility. Losing transitions electrically is certainly possible, especially if it happens in conjunction with collisions (including crossing defenses quickly) or another motor/actuator being operated.

Just for completeness, is the sensor connected to a pair of DIO ports on the RIO, or going to an SRX or Jaguar's encoder inputs? Especially if it's not coming from the DIO, are you sure you're using a 5V supply?
__________________

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.