  In this paper, we present a domain specific process to assist the
verification of observer-based fault detection software. Observer-based fault
detection systems, like control systems, yield invariant properties of
quadratic types. These quadratic invariants express both safety properties of
the software such as the boundedness of the states and correctness properties
such as the absence of false alarms from the fault detector. We seek to
leverage these quadratic invariants, in an automated fashion, for the formal
verification of the fault detection software. The approach, referred to as the
credible autocoding framework [1], can be characterized as autocoding with
proofs. The process starts with the fault detector model, along with its safety
and correctness properties, all expressed formally in a synchronous modeling
environment such as Simulink. The model is then transformed by a prototype
credible autocoder into both code and analyzable annotations for the code. We
demonstrate the credible autocoding process on a running example of an output
observer fault detector for a 3-degrees-of-freedom (3DOF) helicopter control
system.
