Landing Zone Analysis for Autonomous Medevac
In perhaps the most complex scenario, the imaginary casualty is located at the edge of a coal-fired power plant on the Monongahela River. There are many types of obstacles typical of an industrial setting. The helicopter overflew the east edge of the plant at an altitude of 200 meters.
The following images show the steps the system takes in finding an appropriate landing site given a casualty location somewhere in the map.
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Click on any of the images for a more detailed picture.
Step 1: Survey a Point Cloud
The target region is surveyed by flying low over the target region. Here, we did a single pass over the target at an altitude of about 200 meters, which is twice as high as the other data sets. Each measurement of the laser range finder returns a "point" that is registered in a global coordinate frame using the inertial navigation system. The survey results in a collection of points called a "point cloud," which represents the shape of the terrain.
In the picture below, the point cloud is color-coded for altitude. Bands in the color are the same as reading a topographic map.
Step 2: Rough Terrain Analysis
Step 3: Fine Terrain Analysis
Step 4: Landing Site Selection
After the candidate landing sites have been closely examined and ranked, the system then decides where to actually land. An ideal location will not only have a cluster of appropriate landing sites surrounding it, but it will also be close and accessible to the casualty. The final decision is a trade off between proximity to the casualty, and the suitability of the landing location. The decision is shown by the white concentric circles. Notice in the figure below, that the system has chosen to land slightly farther away from the casualty than it could have, in order to reduce the risk associated with landing closer to the obstacles.