Ziegler-Nichols Customization for Quadrotor Attitude Control under Empty and Full Loading Conditions

An aircraft quadrotor is a complex control system that allows for great flexibility inflight. Controlling multirotor aerial systems such as quadrotors is complex because the variables involved are not always available, known, and accurate. The inclusion of payload changes the dynamic characteristics of the aircraft, making it necessary to adapt the control system for this situation. Among the various control methods that have been investigated, proportional-integral-derivative (PID) control offers good results and simplicity of application; however, achieving stability and high performance is challenging, with the most critical task being tuning the controller gains. The Ziegler-Nichols (ZN) theory was used to tune the controller gains for pitch and roll attitude command; however, the performance results were not satisfactory. The response of this system was refined, resulting in an improvement in the reference tracking and the rejection of disturbances. This particular refinement was applied to the quadrotor, and via a reverse calculation, the parameters that allow the tuning of PID gains were obtained, based on ZN. The particularization of the ZN theory applied to a quadrotor with and without a load (termed ZNAQ and ZNAQL, respectively) is proposed and results in a significant improvement in the control system response performance (up to 75%), demonstrating that ZNAQ and ZNAQL are valid for tuning the controller PID gains and are more efficient than the original ZN theory approach.