Mixed H2/H∞ control for two quadrotors transporting a cable-suspended payload

In this paper, we design a mixed H-2/H-infinity controller for two quadrotors transporting a cable-suspended payload. The task is to control the payload to track a predefined trajectory in a confined space. There are two challenging issues: one is the robustness of the controlled system as it is very easy to be affected by exogenous disturbances, and the other is the constrained environment in which the system is asked to pass through a door without any collision. We develop a mixed H-2/H-infinity controller to strike a balance between smoothing the tracking trajectory and resisting the disturbance. The controller also possesses the ability to cope with the constraints imposed on inputs and outputs. The trajectory generation is based on an offline optimisation approach by considering the output flatness of the system. Finally, numerical simulation results are provided and compared against individual H-2 or H-infinity controller.