This post is primarily for you FTC teams that use encoders with your drive motors, and issue "Move Fixed Distance" commands in Autonomous.
We could never work out why our robot seemed much faster in Teleop than Auto. Even though we were using constant speed (rather than power) in both modes.
After our first regional (once we knew we wwere going to Worlds) we decided to find out why this was so.
We ran a series of bench tests on a "dummy bot". The interesting thing we discovered was that the DC Motor controllers would run up to full speed (4000 counts per second) if you were issuing a "Constant Speed" command. But when you issued a "Run to position" command (which was also meant to run at constant speed) the motors only ramped up to 65% speed. After that they clipped and never ran any faster.
So if you were trying to go a fixed distance at 95% speed, you only got 65%.
This isn't a LabVIEW effect, since LabVIEW just sends essentially the same command to the motor controller. It's clearly a Hitechnic motor controller thing.
I created a white paper report and included the test code (which charts the results) and sent it off to Hitechnic several months back. The reply I got was basically "it may be doing that". Which I found very unsatisfying.
I've uploaded the white paper/report here.
http://www.chiefdelphi.com/media/papers/2488
As a result, we completely rebuilt our drive VI's to ONLY use the Constant Speed commands, and we have LabVIEW checking the end of travel. We did some other tweaks along the way, which effectively eliminated the occasional "glitch" which used to terminate some moves prematurely.
The end result was that our Auto sequences ran MUCH faster. A doubler routine which used to take the full 40 secs now had 10 seconds to spare at the end. We had so much time that we could score in the rolling goal, cross the bridge, dispense 5 battons from the high dispenser, and then get back on the bridge to ballence.
Phil.