On the gain synthesis of dynamic and integral sliding mode controllers for quad rotorcraft trajectory tracking

This study explores the development of two control strategies based on the sliding mode approach for quad rotorcraft trajectory tracking. A dynamic and an integral-type controller are designed to ensure that the sliding surface reaches zero within a finite time, resulting in a PD-like structure. Since this structure aids in determining the gains of robust PD controllers, it is utilized for comparative analysis. To account for uncertain dynamics and external disturbances, this work proposes an offline linear matrix inequality (LMI) algorithm that guarantees ultimate uniform stability for both sliding mode controllers. The primary advantage of the proposed LMI-based strategy is its ability to simplify the implementation of a sliding mode controller in complex systems, overcoming challenges associated with their intricate tuning process. Since the proposed algorithm applies to all three controllers, it facilitates the identification of the most effective one based on the system’s dynamic response. A comparative analysis based on error criteria is performed through numerical simulations to validate the effectiveness of the proposed strategies. In addition, a second comparative analysis is conducted between two widely used robust control strategies from the literature and the proposed ISMC. Finally, the effectiveness of the designed algorithm is evaluated using a complex reference trajectory featuring high maneuverability and high-speed flight.