The state machine model in the below figure considers four in-flight states of a small unmanned aerial system (sUAS).
(1 Pfp) (Object)
(Pfp)^(Object)
Collision Path
Object
Flight Path
(1 Pfp) (Object)
(Object)
(Pcp)(Object)
(1 Pcp)(Object)
Adjust Path
(Pap){0Object)}
(Pcp)(Object)
Corrected Path
(1 Pap)^(LObject)
Flight Path, where the sUAS is following the initial calculated flight path, while also monitoring the environment for external objects that could be located on, or intersecting, the flight path.
Adjust Path, in which the sUAS is calculating a revised flight path when an object is detected on the initial flight path.
Corrected Path, which is the sUAS path determined to avoid the risk of collision with the detected objects.
Collision Path, when the sUAS is not able to avoid the total failure resulting from a collision with an object in the external environment; collision could occur in the case of object non-detection, failed path adjustment, or improper revised (corrected) path.
a) Derive the invariant(s) for sUAS collision with an external object. Write each invariant(s) such that, if not violated, it will only evaluate to FALSE.
b) Using TRUE and FALSE evaluations only, derive the execution of the state machine model, and highlight the unsafe cases that violate the invariant(s) identified (i.e., highlight the state machine cases that result in a TRUE evaluation of the invariant(s). Use the below table as an example. Add as many rows and columns as necessary to cover all state machine cases.
