Robust trajectory maneuvering of VTOL aircraft using higher-order sliding mode control (HOSMC)

Area of Science:

• Aerospace Engineering
• Control Systems
• Robotics

Background:

• Vertical Takeoff and Landing (VTOL) aircraft exhibit complex nonlinear dynamics and are susceptible to external disturbances, posing significant control challenges, especially during flight phase transitions.
• Existing control methods often struggle to achieve high precision and robustness in dynamic urban flight environments.

Purpose of the Study:

• To develop and validate a Higher-Order Sliding Mode Control (HOSMC) strategy for small-scale VTOL platforms.
• To improve trajectory tracking accuracy and robustness against disturbances during hover-forward flight transitions in urban conditions.

Main Methods:

• Implementation of a Higher-Order Sliding Mode Control (HOSMC) strategy based on the Super-Twisting algorithm.
• Design of tailored sliding variables and refined gain tuning for the control system.
• Extensive simulation validation under realistic urban flight conditions, including turbulence and thrust perturbations.

Main Results:

• HOSMC demonstrated superior trajectory tracking performance, achieving a maximum error of 0.038 m and an RMS error of 0.017 m.
• The HOSMC strategy showed a 61% improvement in RMS error and a 50% reduction in maximum error compared to Sliding Mode Control (SMC) and Active Sliding Mode Control (ASMC).
• Significant improvements in energy efficiency (up to 20% reduction compared to PID) and smoother control inputs were observed.

Conclusions:

• The developed HOSMC strategy effectively suppresses chattering and enhances control robustness for VTOL aircraft.
• HOSMC offers a promising solution for improving energy efficiency and tracking accuracy in autonomous VTOL operations.
• The findings support the potential of HOSMC for advanced Urban Air Mobility (UAM) applications.