## Autopilot model, subsystem Asymmetrical autopilot modes

The subsystem Asymmetrical autopilot modes, which is part of the systems APILOT1, APILOT2, and APILOT3 contains the following control modes of the 'Beaver' autopilot:

- Roll Attitude Hold (RAH), including turn coordination
- Heading Hold / Heading Select (HH)
- VOR-Navigation (NAV)
- asymmetrical approach mode: Localizer (LOC)

The RAH mode is also used as inner-loop for HH, NAV, and LOC.

In Localizer mode, a switch criterion is used to switch from the Localizer-Armed phase, in which the aircraft is usually flying under HH control, to Localizer-Coupled. Note: for reasons of computing speed, LOC has not been included in the system APILOT1.

The block Select asymm. mode-controller signals in the subsystem Asymmetrical autopilot modes separates the mode-switch settings from the inputvector ymode and reference signals from the inputvector yref for the asymmetrical autopilot modes from the symmetrical mode-switch settings and reference signals.

### More information

See the explanation of the subsystems Mode Controller and Reference Signals for more information about the inputvectors ymode and yref. See also the color definition table for the FDC toolbox and the subsystem Symmetrical autopilot modes.

### References

For a detailed description of the 'Beaver' autopilot, refer to the FDC user-manual. More information can be found in the following references:

1. M.O. Rauw: A Simulink environment for Flight Dynamics and Control analysis - Application to the DHC-2 'Beaver' (PART II). MSc-thesis, Delft University of Technology, Faculty of Aerospace Engineering, Delft, The Netherlands, 1993.
2. P.N.H. Wever: Ontwerp en implementatie van de regelwetten van de De Havilland DHC-2 'Beaver' (in Dutch). MSc-thesis, Delft University of Technology, Faculty of Aerospace Engineering, Delft, The Netherlands, 1993.