## Autopilot subsystem Mode Controller

The autopilot subsystem Mode Controller supplies the switch-settings for the different autopilot modes. The systems APILOT2 and APILOT3 contain radio-navigation modes (Glideslope, Localizer, and Navigation) which start in 'Armed' setting and switch over to 'Coupled' as soon as some switch-criterion is satisfied. The block Mode Controller evaluates those switch-criteria. In the system APILOT1 the radio-navigation modes have been omitted, so in that case Mode Controller only defines the autopilot modes, but does not contain any mode-switching functions.

Before starting a new simulation, double-click the block 'Select Mode and Reference Signals', or type `apmode` at the Matlab command line in order to run APMODE to define the autopilot modes. This utility will generate the vectors ymod1S, ymod2S, ymod1A, and ymod2A in the Matlab workspace. These vectors are defined as follows:

- ymod1S / ymod2S: symmetrical autopilot modes
- ymod1A / ymod2A: asymmetrical autopilot modes
- extension 1: initial autopilot setting
- extension 2: second autopilot setting (used for radio-navigation modes to make it possible to switch from 'Armed' = initial phase to 'Coupled' = second phase)

### Symmetrical modes:

     ymodS = [symm. autopilot modes on/off ,
              symm. outer-loops on/off     ,
              Altitude Hold mode on/off    ,
              Altitude Select mode on/off  ,
              Glideslope mode on/off        ]

with the following combinations for ymodS:

              Pitch Attitude Hold              :  [1 0 0 0 0]
              Altitude Hold / Glideslope Armed :  [1 1 1 0 0]
              Altitude Select                  :  [1 1 0 1 0]
              Glideslope Coupled               :  [1 1 0 0 1]

### Asymmetrical modes:

     ymodA = [asymm. autopilot modes on/off,
              asymm. outer-loops on/off    ,
              Heading Hold/Select on/off   ,
              VOR-Navigation mode on/off   ,
              Localizer mode on/off         ]

with the following combinations for ymodA:

              Roll Attitude Hold               :  [1 0 0 0 0]
              Heading Hold/Heading Select/
                     NAV Armed/Localizer Armed :  [1 1 1 0 0]
              NAV Coupled                      :  [1 1 0 1 0]
              Localizer Coupled                :  [1 1 0 0 1]

### More information

See the source-codes of GSSWITCH.M, LOCSWTCH.M, and NAVSWTCH.M for the switch-criteria used in Glideslope, Localizer, and VOR navigation modes, respectively. See APMODE.M for more details on the mode-initialization of the autopilot.

### References

A detailed description of the 'Beaver' autopilot can be found in the FDC user-manual, and 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.