Type of turns and when they are used.

Types of Turns

1. 3 point (K) turn (forward) This turn does not use a course, instead it drives by steering only, first forward (left or right), then straight backwards, and then forward again (left or right)

2. Calculated turn This is using a precalculated curve to get from the turn start to the turn end. Calculation is based on the geometry only, it does not take obstacles or fruit in account. We use two different algorithms to calculate the path: Dubins (forward only) and Reeds-Shepp (forward or reverse).

3. Pathfinder turn We use the hybrid A* pathfinding algorithm to generate the path between the turn start and turn end. This algorithm can avoid collisions and fruit. There are two variations: a) free pathfinding from turn start to end, where the path is determined only by obstacles and fruit on the field b) drive as much as possible on the outermost headland between turn start and end

Which 180° turn we use when (headland turns are different):

• First, we check if we can make a 3 point turn (canMakeKTurn()):

  • the lateral distance to the next row is less than the turn diameter
  • can reverse with the attached implements (nothing towed allowed here)
  • not an articulated axis vehicle (we can't yet reverse correctly with those)
  • there's enough room on the field to make the turn, that is, turning radius + half work width

• If there is no 3 point turn possible, then:

  • if the turn end is very far and there are headlands, we always use the pathfinder to find a way to the turn end through the outermost headland
  • if there's enough room to turn on the field: = if pathfinder turns are enabled in the settings, use the pathfinder to generate the turn path = otherwise, use a calculated turn
  • if there's not enough room to turn on the field (no or not enough headlands): = if turn on field setting is on, always use calculated turns = if turn on field setting is off, use pathfinder turns if enabled in settings, calculated turns otherwise