S2 Calibration?

deanwesterburg

My S2 robot seems to track strait, however, when I use the Arc_to function or Drive the robot back and forth between 2 points, it's clear it is not making a 180 degree turn.

If I do the following, my endpoints are more than 1" apart and the lines are not parallel

my start point is 0,0

S2.begin_path ' Start the drawing
S2.move_to(0,800)
S2.move_to(0,0)
S2.move_to(0,800)
S2.move_to(0,0)

Is this expected and within tolerance? Is there a calibration program, or is the only way to resolve this to modify my S2 library to specifically match this robot?

Thanks!

Phil Pilgrim (PhiPi)

Dean,

You need a call to end_path to complete your motion sequence.

That notwithstanding, you may need to adjust the calibration for your particular S2. The two parameters of interest are the "full circle" and "wheel spacing" values, which are initialized from the factory as follows:

  DEFAULT_FULL_CIRCLE   = 955
  DEFAULT_WHEEL_SPACE   = 153

By adjusting these two parameters in a call to set_wheel_calibration, you should be able to come closer to repeatability nirvana. Once you've established good values, send the same parameters to write_wheel_calibration to secure them in EEPROM as the defaults for your S2.

Incidentally, accurate tracking requires running on a hard, smooth, level surface.

-Phil

deanwesterburg

Thanks Phil! That's exactly what I needed! I'm surprised I couldn't find this on the forum. Maybe no one else is trying to use their S2 as a plotter!