Now we have the cut downs the flight computer needs to be aware of what its current status is. Traditionally the criteria for triggering a flight termination is exceeding a set altitude or leaving a certain geographic area.
I felt neither of these are suitable, instead I wanted to terminate the flight based on the current rate of ascent. I quickly coded up some current rate of ascent calculations so the payload knows what its current vertical rate is.
Based on this vertical rate it makes decisions about whether its Ascending, Decending, Floating or it has a leak.
Ascent is defined by a Rate of Ascent (RoA) >1 m/s
Descent is defined by a RoA < -2 m/s
Float is defined by a RoA between -1 and 1 m/s
Leak is defined by a RoA < 0 but > -2 m/s
As a test I intend to fly the payload without a pyro but leave this code in so I can see what the payload thinks its RoA is and what decisions it takes based on this information. I’ve introduced a flight status code as follows :
A = Ascending – Nominal Flight
D = Decending – Nominal Flight
L = Leak Condition Detected
F = Float Condition Detected
P = Pyro fired due to decent detection (i.e balloon has burst)
Q = Pyro fired due to detection of a float condition.
R = Pyro fired due to detection of a leak condition.
G = Ground mode prior to launch.
S = Landing mode (this is set when decending and altitude drops below 500m – possibly trigger siren or somthing)
N = No GPS lock
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