Cooperative Control of Multi-Agent Negative Imaginary Systems with Applications to UAVs, Including Hardware Implementation Results

This paper proposes a new formation tracking and containment control methodology for multi-agent systems using Negative Imaginary (NI) systems theory. The proposed control scheme consists of a two-loop configuration in which the inner loop applies an appropriate feedback linearising control law to transform the nonlinear dynamics of each agent into a double integrator system, while the outer loop deploys an NI-based formation tracking and containment control protocol on the linearised double integrator agents. This methodology utilises the characteristic loci technique rather than the well-known Lyapunov-based approaches to establish the asymptotic convergence of the formation and containment trajectory tracking errors. Compared to existing methods, the proposed scheme gives more freedom to select a dynamic controller and relies only on output feedback. As a result, it offers better formation tracking and containment performance and advantages when full-state measurements are unavailable. Finally, a real-time flight experiment was conducted on networked Crazyflie quadcopters to examine the control performance in both healthy and faulty (e.g. a sudden loss of agents, communication failure, hardware faults, etc.) operating conditions.