I decided to try the Terrain following. I downloaded a set of terrain data tiles for my actual position from the web utility “Ardupilot terrain generator” and placed it on the SD card. As soon as I tried in the field to arm, I received a message “Waiting for terrain data”. So I tried to connect the FC via USB to MP with internet connection. After that I was able to arm. Made a flight and I saw, that in FBWB mode the plane automatically maintained the height above the rising terrain. That was OK. But a day after I tried the same route with the same settings (the connection to MP was not necessary for arming), but on OSD I saw the value of Height above terrain was rapidly decreasing as the terrain began to rise. That should mean the FC was using the saved terrain data, but it didn’t maintain a constant height. The same was the case with other attempts, no more copying of the terrain took place. Then I tried another plane, but with the same result, except for the first successful terrain tracking.
My terrain params are:
TERRAIN_ENABLE,1
TERRAIN_FOLLOW,18
TERRAIN_LOOKAHD,2000
TERRAIN_MARGIN,0.05
TERRAIN_OFS_MAX,30
TERRAIN_OPTIONS,0
TERRAIN_SPACING,100
Did anybody have a similar experience with terrain following in AP? Should it work at FBWB also without setting a specific mission?