Cooperative control of multi-tilt tricopter drones applying a ‘mixed’ negative imaginary and strict passivity technique

This paper develops a cooperative controller for a fleet of multi-tilt tricopter drones modelled as Negative Imaginary (NI) systems via closed-loop linearisation exploiting Sliding-Mode Control (SMC) technique. The multi-tilt tricopter model is derived from the first principles, and the SMC method is invoked to obtain a closed-loop linear model of the tricopter plant with six outputs and six inputs. A subspacebased system identification algorithm is developed to identify the linearised drone model enforcing the NI property. The primary control objective is to design a distributed ‘mixed’ NI and strictly Passive control protocol so that the tricopter agents asymptotically reach the desired formation and keep tracking the target. Instead of the Lyapunov approach, the characteristic loci method is used to prove the asymptotic convergence of the trajectory tracking error. Finally, an exhaustive simulation case study is carried out on a fleet of six multi-tilt tricopter drones to demonstrate the feasibility of the cooperative controller presented in this work.