Robust assessment for the design of multi-loop proportional integrative derivative autopilot

In this study a novel robust approach for proportional integrative derivative gain evaluation is proposed. This approach, which can be considered in the class of H_∞ loop shaping methods, is applied to tune the gains of a multi-loop autopilot for mini unmanned aerial vehicles. Nominal stability, nominal performance, robust stability and robust performance of the system are assessed. Root locus method and loop shaping techniques are combined in order to guarantee compliance with robustness requirements and to obtain satisfying flying qualities. Simulation results demonstrate that the method is easy to implement, good robustness and flying performances can be achieved despite a conflicting requirement between these two characteristics.