# Formation Control Technology of Fixed-Wing UAV Swarm Based on Distributed Ad Hoc Network
## 1 Introduction  
The fixed-wing UAV swarm has essential application prospects and has become a current research hotspot. Completing combat missions such as coordinated reconnaissance, early warning, strike, and evaluation in the military field; and realizing disaster emergency, geological survey, and pesticide-spraying tasks in the civilian field [1, 2, 3, 4]. Formation control is one of the key issues to achieve UAV swarm flight [5, 6]. Its primary con-tents include formation maintenance, formation switching, formation obstacle avoidance, and exception handling. The distributed wireless ad hoc network [7] is the core of realizing the cluster unmanned system [8]. The formation control based on the distributed ad hoc network can better reflect the distributed, networked, and centerless characteristics of the cluster system, which is the future development trend of cluster control. The formation control technology for UAV swarm behavior has been extensively studied. [PERSON] [9] proposed the leader-follower method. Its basic idea is that other UAVs follow a leader UAV as followers. [PERSON] et al. [10] and [PERSON] et al. [11] also adopted the leader-follower method to design a control method for the leader and followers in the formation. [PERSON] et al. [12], based on the leader-follower method, proposed a virtual leader method. Its main idea was to treat the formation of a multi-UAV formation as a rigid virtual structure. When the formation moved as a whole, the UAV only needed to track the movement of the fixed point corresponding to the rigid body. [PERSON] and [PERSON] [13] designed a synchronized position tracking controller to improve the effectiveness of using a virtual structure method to maintain formation geometry. [PERSON] and [PERSON] [14] applied behavior-control methods to study the formation of multiplatform formations, such as linear formation and circular formation. [PERSON] and [PERSON] [15] applied behavior-control methods to achieve the purpose of object transportation. [PERSON] et al. [16] used behavior methods to define the concept of the formation geometric center. When flying in formation, each aircraft needs to maintain a prescribed distance from the geometric center, and be able to perceive the movements of other aircraft and reconstruct the formation, similar to the behavior of migratory birds in nature. [PERSON] et al. [17] proposed a feedback linearization method based on consistency for multi-UAV systems to maintain a specific time-varying formation flight geometry. [PERSON] et al. [18] applied the consistency research strategy to study the situation when there were random communication noise and information packet loss constraints in the network, and used the polygon method based on information exchange to achieve formation control. [PERSON] and [PERSON] [19] studied the cooperative control problem of multi-UAV systems, and proposed a cooperative formation control strategy with collision-avoidance capability using decentralized model predictive control (MPC) and consensus-based control. [PERSON] et al. [20] studied the problem of formation control of multiaircraft formation with time-varying formation characteristics when there was a spanning tree in the network topology based on the consistency theory, and obtained the stability conditions of the system. [PERSON] et al. [21] designed a distributed formation controller based on the consistency theory, proving that as long as the network topology was guaranteed to have directional strong connectivity, even if the aircraft was lost during the formation flight, the multiaircraft system could still achieve stable formation control. [PERSON] et al. [22] designed a consistent control protocol for the situation in which the network topology had fixed connectivity, and studied the problem of cooperative formation control of multiaircraft systems forming geometric formations. [PERSON] et al. [23] used evolutionary control theory to complete distributed collaborative control of UAV formations.