Failsafe: Terrain data missing with TERRAIN_ENABLE=0

ArduCopter Copter 4.0
1

On this hexacopter mission flight (stable 4.0.3, log) the mission (spiral 10x12, waypoints altitude 1.5 and 1.7m alternatively) had to be attempted four times till success. On the log appears:

MSG, 472367271, Failsafe: Terrain data missing
ERR, 472367343, 23, 1
ERR, 472701338, 23, 0

MSG, 551025284, Failsafe: Terrain data missing
ERR, 551025352, 23, 1
ERR, 551360045, 23, 0

MSG, 610841934, Failsafe: Terrain data missing
ERR, 610842002, 23, 1
ERR, 611175423, 23, 0

MSG, 663387547, Failsafe: Terrain data missing
ERR, 663387775, 23, 1
ERR, 663721292, 23, 0

spoken Failsafe: terrain data missing was heard, and RTL was started.

However, TERRAIN_ENABLE=0.

Certainly, there is some problem with the altitude:

20200802_Amazon_Hexa4_172_BARO-Alt_RFND0-Dist_RFND1-Dist
20200802_Amazon_Hexa4_172_BARO-Alt_RFND0-Dist_RFND1-Dist1213×486 14.9 KB

(on a summer shiny day with yellow grass below the range finders have problems), but CTUN.DSAlt and CTUN.Alt agree:
20200802_Amazon_Hexa4_172_CTUN-DSAlt-Alt
20200802_Amazon_Hexa4_172_CTUN-DSAlt-Alt1213×392 11.9 KB

This and this describe a similar problem, but on other copter the same mission is perfect or almost perfect (ROI forgotten).

Any suggestion? Thanks.

2

Did you ever find a solution for this? We have similar issues. TERRAIN_ENABLE = 0 and we get flagged Missing Terrain Data. Trying to fly with rangefinder.

3

Guidelines:

  • Adequateness: indoors/outdoors, sunlight.
  • Check thoroughly hardware, cabling, mounting, parameters…
  • Consider independent supply.
  • “Terrain data missing” may come from trying to get data from a rangefinder with copter at too high altitude.
  • The system doesn’t “know” how to go in a mission from being high at a 3 type waypoint (barometer/GPS) to a 10 type (rangefinder) waypoint. If this is the case, insert a type 3 waypoint within rangefinder range (∼3m) as workaround.

BTW, for safety the intermediate 3 waypoint should be higher than the next type 10 waypoint, so the copter should descend then. Because of barometer/GPS imprecision many times I have observed it ascends instead, or even touches ground.

4

Thanks for your reply. We take of to 30 m and then attempt to fly to each consequative waypoint that is set as a terrain waypoint at 30 m. I am not aware of height limitations for copter when flying with terrain following waypoints.