Parachute Min Altitude Questions

ArduCopter Copter 4.0
1

I was wondering if I can get clarification on what “altitude” is being used to check against CHUTE_ALT_MIN to see if it is safe to fire a parachute when you have a rangefinder enabled.

Theoretically, if I take off at the top of a canyon and fly into the canyon (so that my current altitude is below the home altitude), will the parachute be disabled if CHUTE_ALT_MIN is nonzero? If so, does CHUTE_ALT_MIN work with negative numbers?

For instance, if I know I am flying in a canyon with a max depth of 100 meters, and I know my chute needs 10 meters to arrest the fall, could I set CHUTE_ALT_MIN to -90 so that it can fire as soon as I take off, but it won’t fire if I am within 10 meters of the canyon floor?

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2

@mike_d,

The CHUTE_ALT_MIN is an altitude above home and as far as I can tell from looking at the code it will accept negative numbers. So it treats “0” as a special case meaning the vehicle altitude is removed as a criteria for releasing the parachute, but if it’s negative it should still be used.

3

Thanks for the clarification! I appreciate it!

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