View Single Post
  #4   Spotlight this post!  
Unread 28-09-2011, 22:03
Ether's Avatar
Ether Ether is offline
systems engineer (retired)
no team
 
Join Date: Nov 2009
Rookie Year: 1969
Location: US
Posts: 8,094
Ether has a reputation beyond reputeEther has a reputation beyond reputeEther has a reputation beyond reputeEther has a reputation beyond reputeEther has a reputation beyond reputeEther has a reputation beyond reputeEther has a reputation beyond reputeEther has a reputation beyond reputeEther has a reputation beyond reputeEther has a reputation beyond reputeEther has a reputation beyond repute
Re: pic: FRC973 Presents Emperor Swerve

Quote:
Originally Posted by BeltSanderRocks View Post
How easy is it for you to do this? (how much driver input is required?)

I remember accomplishing this on our robot, but it was a very tough maneuver.
Adam beat me to it, but I'll go ahead and post this in case it adds anything to the explanation.

If you have a stable and reliable gyro, it can be used to convert "field-centric" translation commands into the corresponding robot-centric translation commands. Some maneuvers that would otherwise take a great deal of driver practice and skill can be greatly simplified by doing this.

The way a field-centric command works is this:
1) The driver uses the joystick (or other input) to command the vehicle to go in desired direction (with respect to the field)

2) The computer takes this command, and uses the gyro reading to figure out what the "robot-centric" commands (fore/aft and port/starboard with respect to the robot) must be to accomplish the driver's desired motion.
If the driver is commanding a constant field-centric direction and speed, and the vehicle is simultaneously rotating, then the computer is continuously converting that constant field-centric command into the time-varying fore/aft and port/starboard robot-centric commands necessary to keep the vehicle moving in the direction and speed commanded by the driver, regardless of the vehicle's angular orientation.

So the driver can command field-centric "forward" (usually defined as "downfield" - away from the driver station) and the vehicle will travel in a straight line in that commanded direction regardless of the independently commanded vehicle rotation (subject to the caveats mentioned earlier).



Reply With Quote