Cooperative Flight Control of a Fleet of Quadrotors Using Fractional Sliding Mode With Potential Field Algorithms

In this paper, a leader-follower-based cooperative and formation flight control is designed for a group of quadrotors using new forms of fractional sliding mode control (FSMC) strategy accompanied by the potential field algorithm. The FSMC strategy is employed as an inner controller to stabilize each individual UAV quadrotor while the potential field function is used as a formation algorithm (output controller) in order to keep a desired shape formation during the navigation of the fleet. Firstly, the stability of a single quadrotor subjected to external disturbances is addressed by designing an FSMC in addition to a classical PID controller. The FSMC is responsible for stabilizing the altitude and attitude of the vehicle while the responsibility of the PID is to control the two-dimensional (x-y) position of the UAV. Lyapunov-based sliding condition is used in the design of the fractional control strategy to guarantee system stability. The controller's parameters are tuned using the genetic algorithm (GA) to obtain better performance and more robustness against external disturbances. The potential field algorithm is used to generate the paths that are required for the fleet of vehicles to navigate while keeping a prescribed formation shape. This is done by using the attractive potential field to attract the followers toward the leader and the repulsive potential field to repulse every two neighboring followers in order to keep a required distance between them. Simulation results have proved the efficiency of the proposed control system for both the single and multi-agent cases.