Twin Tiltrotor UAV Trajectory Planning Considering Directional Constraints and Shortest-yaw Paths

The traditional multi-rotor unmanned aerial vehicle (UAV) is widely used in tasks such as industrial inspection, cargo transportation, disaster search and rescue. However, in confined spaces, their flight is often limited by vehicle size and attitude adjustment capabilities, thereby affecting passability efficiency and flight safety. To address this, a trajectory generation strategy considering directional constraints and calculating yaw angle from planar velocity components is proposed for the tandem twin tiltrotor UAV platform in constrained environments. This proposed method improves the minimum second-order acceleration (SNAP) trajectory generation approach, enabling coordinated optimization of position and yaw trajectories, a shortest-yaw path algorithm and an interpolation smoothing algorithm near waypoints are designed to enhance the smoothness and safety of the flight process. Comparative results with the minimum SNAP method, which does not consider yaw direction constraints, demonstrate that the improved minimum SNAP method is more suitable for twin tiltrotor UAV platforms. Furthermore, the effectiveness and applicability of the proposed method are validated through extensive experiments.