Virtual Structure Method UAV Distributed Formation Control Based on Improved Super-Twisting Sliding Mode

In the UAV formation control, the virtual structure method no longer relies on the dominance of the UAV leader who may have faults, but defines a virtual center or virtual rigid body. The UAVs only need to maintain relative position in the virtual rigid body coordinate system. However, the communication and calculation are concentrated in the virtual center, resulting in excessive local communication pressure. Besides, the formation effect is not satisfying when the number of UAVs is large. Therefore, this paper considers the combination of distributed communication strategy and virtual structure method, and an improved formation controller is proposed based on the super-twisting algorithm. With two fast integer power linear terms introduced, the controller has a better effect of suppressing chattering and speeding up the convergence of tracking errors. Furthermore, the sign function is replaced by the saturation function with variable boundary layer. Different from fixed boundary layer, the thickness of variable one will decrease gradually as the tracking errors approach the sliding surface, which enables to diminish chattering while not influencing the control effect. In addition, the improved formation controller in this paper can ensure that the velocity and acceleration tracking errors converge to zero so the consistency of UAV clustering can be achieved.