Object Avoidance with Dijkstra’s

Copter and Rover support Dijkstra’s for path planning around fences and stay-out zones in Auto, Guided and RTL modes. This well known algorithm internally builds up a list of “safe areas” calculated from the fence and stay-out zones and then finds the shortest path to the destination.

../_images/oa-dijkstras.png

Warning

Dijkstra’s does not support avoiding objects sensed with lidar or proximity sensors

Warning

Dijkstra’s does not support Spline Waypoints.

Configuration

  • OA_TYPE = 2 (Dijkstra). You may need to refresh parameters after changing this to see the parameters below.

  • OA_MARGIN_MAX: the distance (in meters) that the vehicle should stay away from the fences and stay-out zones

  • OA_OPTIONS bit 2 (+4 to the value) can be set to use S-Curves around fence corners in the planned path to speed up turns. Note that using S-Curves, instead of the normal “approach,stop, turn, proceed” method of path planning around sharp fence corners, could still result in a fence breach.To avoid this WPNAV_RADIUS should be set smaller than FENCE_MARGIN. Also waypoints should also be placed at least 10m from fence boundaries.

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