Autonomous Quad-plane UAV

Autonomous Quad-plane UAV

Hybrid VTOL (Vertical Takeoff and Landing) aircraft combine the versatility of multirotors with the efficiency of fixed-wing planes. This project involved the complete design, build, and tuning of a "Quad-plane" platform for autonomous survey missions.

System Architecture

The aircraft uses a standard fixed-wing airframe retrofitted with four lift motors mounted on carbon fiber booms.

• Flight Controller: Pixhawk 6C running a custom-configured PX4 Autopilot stack.
• Airframe: 1.8m wingspan composite foam platform.
• Propulsion: 4x Brushless motors for lift, 1x Pusher motor for cruise flight.

Technical Challenges

1. Transition Logic

The most critical phase of flight is the transition from hover to forward flight. I tuned the transition airspeed thresholds and blending time constants to ensure stability.

Implementation Note: The transition is managed by a state machine that ramps up the pusher throttle while gradually tapering off the quad motors once aerodynamic lift is sufficient.

2. Vibration Isolation

Initially, high-frequency vibrations from the lift motors affected the accelerometer data. A custom 3D-printed vibration damping mount was designed in SolidWorks to isolate the flight controller.

Flight Testing

Field tests demonstrated successful autonomous missions:

1. Vertical launch to 30m.
2. Transition to fixed-wing mode at 15 m/s.
3. Waypoint navigation.
4. Back-transition and precision vertical landing.

This platform effectively doubled the flight time compared to a standard quadcopter of similar payload capacity.