- OK so let’s say we can track a course-line and do a U turn in the headland. What’s next? Could we maybe define a track for doing the entire field, headland, straight passes, turns; the whole field, everything? I think we could. A field course could be computer generated, but the computer would need to know a few things: the perimeter of the field, of which it is understood that the perimeter can not be breached. Also, the perimeter of any obstacles such as sloughs, wet spots, bushes, utility poles, rock piles buildings and what have you. The tractor or implement is not allowed inside this obstacle perimeter. The computer must also have knowledge of the width of the implement, its drag distance and the minimum turning radius as well as the maximum change or the upper limit of the turning rate. (this will define the transition distance in a turn). The start position, or field entry, and end of the track position (field exit) would be needed. The desired pattern, round and round, or parallel passes would be needed. If parallel lines are selected, then the direction of the parallel lines would be input, unless you let the computer find the optimum direction for best efficiency.
How do we establish the perimeter of the field and the obstacles? Some have suggested that this could be done by remote sensing or from Google Earth. I would argue that that is not accurate enough. One must be on the ground making continuously scrutinizing as to where the perimeter is precisely. What’s a wet spot and what’s not? To make that call, one must be right there. I would suggest that a small quad ATV could be used equipped with a GPS receiver; the coordinates would be collected to define the perimeter as the farmer drives the quad precisely where the perimeter is to be established. Most perimeters are stable and the remain the same year after year. However, there are some perimeters or parts thereof that would require updating such as wet spots. In the end, the perimeters of the field and the obstacles would be a set of coordinates that could easily be input to a computer. With all the other fore mentioned parameters; we would be ready for the next step – to develop a series of coordinates, from the start to the finish that would define the track that we want the tractor to drive. This would include the straight lines, the turns, the headlands – everything. Defined by a long series of coordinates. The objective of the computer program that makes the course would be to have the entire field covered, without any missing, with the shortest distance for the greatest efficiency. By allowing some flexibility in some of the inputs, it might be possible to work the field with an even shorter distance. For example, if one adjusted the angle of the parallel lines. The best direction for parallel passes, is to be parallel with the longest part of the field which provides the longest passes, with the fewest turns. The nice thing about predetermined computer-generated courses is that they can be done repeatedly for the best possible course. With manual driving, we find that the last pass always involves considerable overlap. With the computer-generated courses the last pass can be adjusted to minimize the amount of overlap.
How much more efficient would a computerized course be? In one study, driving a quarter-section (160 acres) with a 60’ sprayer: driven manually was 42 km but a computerized predetermined course was 34 km. This was 23% more. As a rule of thumb, manual driving can be improved by 10% by eliminating lateral overlap, and another 10% by making optimum turns and smart decision in adjusting the patterns position and in negotiating turns.
A hybrid computer/manual means of developing a predetermined course by having the operator of the computer manually design the course by hand. This might be a way to get computer aided courses before developing a sophisticated computer program.
If the tractor is now able to follow a predetermined course from start to finish without human intervention, one may ask: Why do we need an operator sitting on the tractor?