The Flight Guidance System (FGS)
compares the
measured state of an aircraft (position, speed,
and attitude) to the desired state and generates
pitch and roll guidance commands to minimize
the difference between the measured and desired
state. When engaged, the Autopilot (AP) translates
these commands into movement of the aircrafts
control surfaces necessary to achieve the
commanded changes about the lateral and vertical
axes. An FGS can be further broken down
into the mode logic and the flight control laws.
The mode logic accepts commands from the
flight crew, the Flight Management System
(FMS), and information about the current state
of the aircraft to determine which system modes
are active. The active modes in turn determine
which flight control laws are used to generate
the pitch and roll guidance commands. The active
lateral and vertical modes are displayed (an
Instrumentation System (EFIS)).
Acknowledgement: R.W. Butler, S.P. Miller, J.N. Potts and V.A. Carreno, A Formal Methods Approach to the Analysis of Mode Confusion. In AIAA/IEEE Digital Avionics Systems Conference, October, 1998.
