Formation Flight Control System Research Articles

Finite time fault tolerant tracking control for multiple unmanned aerial vehicles with actuator faults

SummaryAn adaptive fast nonsingular integral terminal sliding mode control scheme is proposed for the distributed formation control problem of multiple unmanned aerial vehicles (UAVs) affected by actuator faults and external disturbances. In order to achieve a good cooperative tracking performance of UAVs during mission execution, the adverse effect of the lumped disturbances composed of actuator failures, wind and vortex disturbances is estimated by the cerebellar model articulation neural network, meanwhile the tangent function is introduced to eliminate the chattering of the sliding mode. Then the analysis of superior convergence performance of the fast nonsingular integral terminal sliding manifold is implemented, and the finite time stability of the closed‐loop formation flight control system is proved. Finally, the simulation experiments verify that the proposed approach is superior to the nonsingular integral terminal sliding mode control for the formation control system of faulty multiple UAVs.

Maneuvers During Automatic Formation Flight of Transport Aircraft for Fuel Savings

Formation flying techniques, demonstrated by migratory birds, have the potential to significantly save energy when two or more transport aircraft fly the same route at the same time. In fuel-saving formations, aircraft are flying straight trajectories for most of the time. For proof of concept, however, how vertical and lateral maneuvers can be flown has to be investigated. Those investigations require a flight simulator that is equipped with adequate flight mechanical models. Not much research exists on maneuvers of formation. The paper addresses the components that are needed to perform this research with real-time flight simulations. They are, first, a method to model wake vortices on curved trajectories; second, a formation flight control system, which comprises a method for the relative position determination, the design of control laws, and suitable cockpit displays; and third, techniques that allow vertical and lateral flight maneuvers. Two different strategies to position the following aircraft relative to the wake vortex during turns are described, and simulation results show their differences in terms of fuel savings and passenger comfort. Piloted flight simulator tests confirmed the usability of the proposed flight techniques for formation maneuvers, and the participating airline pilots indicated general consent to the concept.

Multivariable adaptive distributed leader-follower flight control for multiple UAVs formation

ABSTRACTThe Unmanned Aerial Vehicles (UAVs) become more and more popular due to various potential application fields. This paper studies the distributed leader-follower formation flight control problem of multiple UAVs with uncertain parameters for both the leader and followers. This problem has not been addressed in the literature. Most of the existing literature considers the leader-follower formation control strategy with parametric uncertainty for the followers. However, they do not take the leader parametric uncertainty into account. Meanwhile, the distributed control strategy depends on less information interactions and is more likely to avoid information conflict. The dynamic model of the UAVs is established based on the aerodynamic parameters. The establishment of the topology structure between a collection of UAVs is based on the algebraic graph theory. To handle the parametric uncertainty of the UAVs dynamics, a multivariable model reference adaptive control (MRAC) method is addressed to design the control law, which enables follower UAVs to track the leader UAV. The stability of the formation flight control system is proved by the Lyapunov theory. Simulation results show that the proposed distributed adaptive leader-following formation flight control system has stronger robustness and adaptivity than the fixed control system, as well as the existing adaptive control system.

屋外環境下におけるマルチローターヘリコプターの編隊飛行制御システム

屋外環境下におけるマルチローターヘリコプターの編隊飛行制御システム

Formation Flight of Multiple UAVs via Onboard Sensor Information Sharing.

To monitor large areas or simultaneously measure multiple points, multiple unmanned aerial vehicles (UAVs) must be flown in formation. To perform such flights, sensor information generated by each UAV should be shared via communications. Although a variety of studies have focused on the algorithms for formation flight, these studies have mainly demonstrated the performance of formation flight using numerical simulations or ground robots, which do not reflect the dynamic characteristics of UAVs. In this study, an onboard sensor information sharing system and formation flight algorithms for multiple UAVs are proposed. The communication delays of radiofrequency (RF) telemetry are analyzed to enable the implementation of the onboard sensor information sharing system. Using the sensor information sharing, the formation guidance law for multiple UAVs, which includes both a circular and close formation, is designed. The hardware system, which includes avionics and an airframe, is constructed for the proposed multi-UAV platform. A numerical simulation is performed to demonstrate the performance of the formation flight guidance and control system for multiple UAVs. Finally, a flight test is conducted to verify the proposed algorithm for the multi-UAV system.

Autonomous Formation Flight Control System Using In-Flight Sweet-Spot Estimation

A formation flight control system that addresses the unique environment encountered by aircraft flying in formation and in the upwash of the leading aircraft that leads to a scenario with minimum induced drag at the trailing aircraft (sweet spot) has been designed. To test the control system, a simulation environment that adequately represents the aerodynamic coupling effects between aircraft flying in formation and implements an incremental nonlinear dynamic inversion-based formation flight control system has been created. Since the exact position of the sweet spot is not known or measured, the research presented in this paper uses an advanced extremum-seeking algorithm that uses an extended Kalman filter to estimate the wind gradients to automatically steer the trailing vehicle toward the sweet spot. Monte Carlo simulations for two and three aircraft formations have shown that the algorithm has the ability to consistently find the sweet spot and is robust to errors due to turbulence.

Towards Automatic Flight Control for Commercial Airliners in Formation Flight

This paper presents research done towards the goal of achieving automatic flight control for commercial airliners in formation flight. The motivation for this research is to ultimately reduce fuel-consumption through a reduction in the drag of the follower aircraft, which is a result of the formation flight. Traditional aerodynamic equations for conventional flight of fixed-wing aircraft are expanded to include formation flight interactions. A trim analysis uncovers risks, challenges and feasible trim regions for the formation follower to maintain. These regions include a potentially risky region which is sandwiched between two untrimmable regions, with respect to a maximum aileron setting, and an outside region which has only one untrimmable bound, making it less risky but with lower fuel-consumption benefit. Next, a state space representation is constructed, allowing for a linear dynamics analysis. The poles and their movement as a function of the lateral and vertical separation of the follower aircraft relative to the leader aircraft are shown, and indicate greater changes in flight dynamics due to vertical separation than to lateral separation. The results of the trim analysis and linear dynamics analysis form the basis for the design of a formation flight control system.

Formation Flight Control of Small Unmanned Helicopters

In this paper, we describe a model based formation flight control of multiple small-scale unmanned helicopters. We design the autonomous formation flight control system as leader-following configuration. In order to achieve good control performance under the system constraint, “model predictive control” is used for the translational position control of follower helicopters. Position constraints such as moving range and collision avoidance problem are considered in the real time optimal control calculation. To achieve a robustness against disturbance, a minimal order disturbance observer is used to estimate the unobsevable state variables and disturbance. The simulation results are presented to show the feasibility of the control strategy. The designed controller is implemented in a laptop on the ground station by C ++ without any other optimizing software. The formation flight control experiment is carried out using two helicopters. The experimental result shows the accurate control performance. The position constraint capability is confirmed through the experiment with the single helicopter. Finally, the robustness against wind is verified by the windy condition experiment.

Automatic formation flight control

The problem of automatic formation fight control is addressed. An aircraft formation consisting of a Leader and Wingman is considered and this novel dynamical system is carefully modelled and analyzed. The subsequent synthesis of a Proportional plus Integral formation hold autopilot is greatly facilitated by our observation that the formation flight control system is amenable to decomposition. Extensive simulations of the nonlinear formation flight control system were performed to validate the proposed formation hold autopilot design.