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Action Models

 

Action models (also known as Flight Directors) are the top-most models in an ACS, ultimately rooted in Sensor data and flight Objectives. Action models are used to update displays and manipulate Effectors.

Usually, each action model corresponds to an error model, spanning the dimensions of dimensions of vertical, lateral and longitudinal control, but where Terrain following is dealt with independently. Values that are needed in order to direct flight typically include:

Lateral:
Heading Error, Heading Error Gain, Roll, Roll limit, Roll Gain, Lateral Error Scale Factor, Trim Roll.
Longitudinal:
Speed Error, Pitch, Speed Error Gain, Pitch Limit, Speed Error Limit, Longitudinal Cue Gain, Longitudinal Cue Error Scale Factor, Pitch Cue Limit.
Vertical:
Altitude Error, Pitch, Roll, Vertical Velocity Lead, Vertical Velocity, Collective Position, Altitude Error Gain, Pitch Gain, Roll Gain, Altitude Error Limit, Coupled vertical command limit, Vertical Velocity Coupled Gain, Vertical Velocity Gain, Collective position gain, Collective position error scale factor, Cue Limit.
Terrain Following:
g-command, Collective Position, g-command gain, Coupled vertical command limit, Vertical Velocity Coupled Gain, Collective position gain, Collective position error scale factor, Cue Limit.

In Avionics Control Systems, most actions are represented as sets of desired effector settings (on/off values, categorical choices, numerical levels, etc) of mechanical components, tailored to the particular kinds of effectors contained on the aircraft.

Design Steps

Maintain attributes representing desired effector settings, in a form useful for Effecting flight. Partition common logical effector settings into common groupings, normally resulting in a bundle of submodels rather than a single action model. In addition to Error Model values, arrange inputs from Navigation Models, from Monitoring and Control, and/or directly from simple Sensors to determine if effectors are enabled and available for manipulation, and invoke associated Action Functions to compute associated action values and Update attributes.



next up previous
Next: Staging Up: Design Patterns for Avionics Previous: Error Models



Doug Lea
Tue Mar 28 08:50:41 EST 1995