Distributed Output-Feedback Formation Tracking Control for Clustered Quadrotors

In this article, we study the cooperative formation tracking problem of clustered quadrotors without velocity and angular velocity measurements. In particular, the clustered quadrotors are required to track a reference trajectory while preserving a well-defined formation shape. However, the information interaction among the quadrotors is local and the reference trajectory information is only known to partial quadrotors. To overcome the aforementioned dilemmas caused by measurement incompleteness and interaction restriction, a distributed output-feedback control algorithm is proposed based on the cascaded framework. To be specific, by introducing two auxiliary dynamics with saturation constraints on their states, a distributed command force with a saturation attribute is first developed in the outer position loop. Next, in terms of a self-contained selection criterion of the control parameters, a bounded applied thrust and a nonsingular command attitude are extracted from the developed command force. Whereafter, an applied torque resorting to another auxiliary dynamics is developed in the inner attitude loop for the purpose of tracking the command attitude. It is shown that, despite the absence of the velocity and angular velocity information of clustered quadrotors, the concerned cooperative formation tracking objective is fulfilled by the proposed distributed control algorithm. Finally, simulations are performed to validate the built theoretical results.