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Levy lines in Surface

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April 25, 2015 05:01PM
I was disappointed with the "enhancements" to levy drawing program in the latest update. In my opinion there will never be the possibility for auto steering levy lines on fields that haven't been precision graded until the idea of turn radius as the method to stay close enough to the raw contour lines is abandoned. I am unsure of the programing problems that might be encountered with a different method but the current method of designing just is not practical for auto steering levies. If you set the radius at say 25' the turns on basically level areas are too many and too sharp. If you set the radius at 100', it may work fine for level areas but in areas with more slope the turns are not sharp enough to stay on grade. Flagging the areas that are out of your selected tolerance is somewhat useful, but an experienced levy person can see them without the flags. Changing the levies using the edit node program creates the same problem as having a sharp radius. The node tool is almost impossible to use without making the resulting corrections being too abrupt in the field.

We have used the levy design program for several years and it does work, but we use it by putting the turn radius in at 25' which gets the levies close enough to the contours. Then we manually steer the tractor to take out the unnecessary sharp turns.

If a field is surveyed by laser or GPS and survey marks drawn by a small tractor or pickup, the resulting lines many times contain sharp turns and may look like a continuous "s" going across the field. The sharp curves of the "s" representing where the survey had gotten too low or too high. So a relatively straight line through the "s" represents the most likely true contour. Your system could be at least that accurate maybe more and still use auto steer, if a different approach to steering is taken.

Keeping in mind the levy builder wants the levy as straight as possible as long as it is within certain elevation tolerances. For example a levy should start out on grade with no set turn radius, if the line gets .01" off turn back to grade at say 100' radius; if that doesn't correct and the lines goes to .02 decrease the radius to 50'; if it continues to increase off grade to .03 decrease to 25' radius ; if it continues to .05 increase to 15' or as sharp as the tractor can turn. I don't know if that example actually has the correct increments, but the principle is the method that an experienced levy puller instinctively uses if he is following a physical line. As I mentioned earlier I don't know the programing problems using this example, but I am confident that the current method for drawing levy lines will not approximate the skill of a experienced driver.
SubjectAuthorPosted

Levy lines in Surface

Gary ColesApril 25, 2015 05:01PM

Re: Levy lines in Surface

Scott NusbaumApril 27, 2015 03:01PM



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