## 3 Module of Maneuver Generation  
Fixed-wing UAVs have high maneuverability and flexibility and can make various maneuvers, such as rolls and climbing. Generally, in the conventional collision avoidance algorithm, the aircraft maneuvers are modelled according to a three degrees of freedom motion rather than six degrees of freedom motion. The 3 Degrees of Freedom (3 DOF) motion is always used in algorithms in which collision avoidance occurs more than 20 s before the collision, the performance parameters of different aircraft are not taken into consideration, and the procedure of the maneuver is ignored. However, in this paper, the collision avoidance occurs approximately 5 s before the collision, and the procedure of the maneuver is the procedure of collision avoidance. Fixed-wing aircrafts can generate a maneuver style (MS) in almost all directions for collision avoidance. However, in relevant studies [24; 25; 26], the MS is set to a group of specific categories. In this paper, according to the characteristics of fixed-wing aircraft, the MS is defined to nine types. Restricting MS to special types can reduce the system budget, improve calculation speed, and ensure rapid response to collision. As shown in Table 1, in this paper, the MS consists of seven roll-and-pull maneuvers, one dive maneuver and one maintain maneuver. The roll-and-pull maneuvers describe an aircraft that is commanded to bank angle while pulling a 5 g overload. The bank command is an incremental change from the current bank angle at the discrete command of \(-90^{\circ}\), \(-60^{\circ}\), \(-30^{\circ}\), \(0^{\circ}\), \(30^{\circ}\), \(60^{\circ}\), \(90^{\circ}\). The dive maneuver is that the aircraft holds a constant bank angle while performing a -0.5 g push. The maintain maneuver is that the bank angle and g-loading are held constant. Seven of nine MS are specified as climbing for the consideration of safety. Compared with climbing, diving has the risk of ground collision. In addition, for a fixed-wing UAV, a roll is the most agile maneuver for collision avoidance.  
Due to the hardware limitation of computing, processing and data transmission, each aircraft only shares three trajectories among participants. Therefore, the algorithm should choose three  
\begin{table}
\begin{tabular}{c c c} \hline \hline
**Maneuver Style (MS)** & **Change of Bank Angle** & **Overload** \\ \hline Roll and pull & \(-90^{\circ}\) & \(+5\) g \\ Roll and pull & \(-60^{\circ}\) & \(+5\) g \\ Roll and pull & \(-30^{\circ}\) & \(+5\) g \\ Roll and pull & \(0^{\circ}\) & \(+5\) g \\ Roll and pull & \(60^{\circ}\) & \(+5\) g \\ Roll and pull & \(90^{\circ}\) & \(+5\) g \\ Maintain & \(0^{\circ}\) & \(0\) g \\ Dive & \(0^{\circ}\) & \(-0.5\) g \\ \hline \hline \end{tabular}
\end{table}
Table 1: Maneuver style.  
Figure 1: Structure of the algorithm.  
available maneuvers from the nine maneuvers first. The procedure of preselection does not need data-transportation among participants and is only based on the geometric relations and motion relations between the host aircraft and threats, including those that are forward or backward, above or below, or on the left or right side of the aircraft.