Project brief
A fully digital autopilot for light twin-engine aircraft implementing inner-loop attitude control and outer-loop navigation modes. The system features non-linear gain scheduling across the flight envelope, dual-channel redundancy with cross-channel monitoring, and supports altitude hold, vertical speed, heading select, LNAV/VNAV navigation, and ILS/LOC/GS approach and tracking modes with automatic go-around logic.
The record describes an integrated flight-control development effort spanning models, embedded control, and hardware-in-the-loop evaluation.
The engineering challenge
Coordinate attitude stabilization and navigation modes across changing aircraft operating conditions.
Engineering approach
- Separate fast attitude loops from outer navigation control.
- Schedule gains across the stated operating envelope.
- Use channel monitoring, authority limits, and HIL scenarios to examine engagement behavior.
Features & capabilities
- Inner-loop attitude control (pitch, roll, yaw) at 100Hz
- Outer-loop modes: ALT, VS, IAS, HDG, LNAV, VNAV, APP, G/A
- Non-linear gain scheduling over Mach 0.1–0.45 envelope
- Dual-channel redundancy with cross-channel monitoring (CCM)
- Auto-throttle with N1 and IAS hold modes
- Hardware-in-the-loop simulation tested with FlightGear
- Pilot-selectable engagement authority limits per DO-1C
- ARINC 429 FMS coupling for LNAV/VNAV tracking
Software & engineering tools
Model-Based Design (Simulink), dSPACE HIL, STM32H7 (dual), Altium Designer, MATLAB Control System Toolbox