Distributed Cooperative Control And Statement Estimation For Networked Multiple UAVs Based On Consensus Theory

Cooperative operation for multiple unmanned aerial vehicles(UAVs) is the main en-gagement manner and the trend of development in the future. With the rapid development and wide employment of the network technology, cooperative manner in networks may improve the operational efficiency greatly. There are also some significant challenges for distributed control and decision problems, such as the influence of the constraints condi-tions, i.e., network delays, time-varying network topologies and uncertain disturbances. It is not only the original impetus to cooperative control and decision of multi-UAV, but also it is an important manifestation of enhancing the autonomy of the UAV. This paper investigates some exploratory work on the multi-agent system consensus theory under the network constraints, and as a means to discuss the rendezvous in mission area and cooper-ative target observation during multi-UAV cooperative engagement. The main work and contributions are as follows:(1) Under the constraint conditions including network delays and time-varying net-work topologies, the delay dependent convergence criteria are given and proved to achieve average consensus for multi-agent systems. By the idea of state decomposition and space transformation, the convergence property of average consensus is equivalent to the stabil-ity of the corresponding subsystem. Then, the common Lyapunov-Krasovskii functional is employed to analyze the stability. In order to get the criteria with lower conservativeness (that means the degree of deviation from the theoretical value, the lower the conservative-ness, the more close to the theoretical value), Free-weighting Matrices are used to verify the negative definite of the Lyapunov-Krasovskii functional. Further, the criteria are ob-tained through solving the corresponding feasible linear matrix inequality(LMI). Lastly, the convergence criteria for multi-agent systems with/th-order chain integrator dynamics are presented with the assumption that the coefficient parameters in the consensus protocol satisfying the Hurwitzs stable. The proposed criteria can overcome the difficulty of con-structing public or multiple Lyapunov functional by frequency-domain method, and the max tolerant upper bounds on network delays can be obtained conveniently using math-ematical package. Numerical examples and simulation results show the effectiveness of the proposed criteria, and the conservativeness is lower than the existing results. (2) Under the constraint conditions including network delays, disturbances and time-varying network topologies, the delay dependent convergence criteria are given and proved to achieve robust consensus for multi-agent systems. By using the idea of state decompo-sition and space transformation, the condition for guaranteeing robust consensus is equiv-alent to the robust stability of the corresponding subsystem, i.e., stability with zero dis-turbance and nonzero disturbance. Then, the common Lyapunov-Krasovskii functional is built to analyze the robust stability, and the Free-weighting Matrices method is used to get the criteria which can be obtained through solving the corresponding feasible nonlin-ear matrix inequality(NLMI). Nonlinear minimization is employed to deal with the NLMI criteria like solving cone complementarity problem. Then, the iterative LMI algorithm is obtained, and the max tolerant upper bounds on network delays can be obtained. Further, the conclusions are expanded to the robust consensus for multi-agent systems with discrete dynamics. Convergence criteria reveal the relationship between the network delays, de-lay differential rate, control protocol for robust consensus and the index H∞performance. It is the theoretical basis to design the control protocol for robust consensus meeting the given H∞robust performance under complex network constraints. Numerical examples and simulation results show the effectiveness of the proposed criteria, and the conserva-tiveness is lower than the existing results.(3) By delay dependent average consensus theory, distributed cooperative control methods are proposed to solve the rendezvous problem in mission area for multi-UAV system in network. The mathematical description of rendezvous problem is established, and the framework to be solved in distributed manner is provided based on the method of coordination variables and coordination function. It can be used to decrease the trans-mission of the redundant information, and reduce the influence of the limited network conditions on rendezvous task to some degree. Considering the characteristics of the task, delay dependent average consensus for multi-agent system is improved as follows: The non-cooperative optimal consensus(NCOC) algorithm, which can minimize the cost func-tion of each platform, is presented for the "selfish" UAVs. The expression of NCOC con-trol protocol is given theoretically by Hamilton-Jacobi-Bellman equation and its boundary condition; On the other hand, the cooperative game based optimal consensus(CGOC) al-gorithm, minimize the cost function of the whole multi-UAV system, is presented for the "cooperative" UAVs. The expression of CGOC control protocol is given theoretically by cooperative game and sensitivity parameter method. Moreover, two distributed coopera-tive control methods for rendezvous problem are proposed, i.e., NCOC method and CGOC method. The proposed methods emphasis on the trajectory control of the platform, thus weaken the requirements of the path planning algorithm for UAV. It can reduce the diffi-culty of solving rendezvous problem, and strengthen the dynamic response capabilities of the multi-UAV system. Simulation results show that the proposed two distributed cooper-ative control methods are valid for solving the rendezvous problem for multi-UAV system in network, and the CGOC method is better than NCOC method in terms of optimal and dynamic response.(4) By delay dependent robust consensus, distributed state estimation method is pre-sented to solve the cooperative target observation for multi-UAV system in network. Con-sidering the loose communication structure of multi-UAV system and the complexity of the networks constraints, the iteration mechanism with double time-window is designed including local prediction/update window and consensus fusion window. The distributed unscented information filter (RC_DUIF) method is given base on the robust consensus un-der discrete time domain. The influence of the convergence property of consensus to the estimation precision is theoretically analyzed. That reveals the fundamental reason for the covariance error of RC_DUIF method is greater than the centralized information filtering method. RC_DUIF method is valid for cooperative target observation under the complex network constraints including network delay, disturbances and time-varying topologies uncertainty. It has the characteristics of lower computational complexity and communi-cation complexity. So it can be implemented easily. Lastly, the Monte Carlo simulation experiments indicate that RC_DUIF algorithm is robust to complex network constraints, and has the outstanding performance on average estimation error, average consistency er-ror and average trace of the covariance matrix, which can meet the requirement of the real time estimate of non-linear target for multi-UAV system under complex network.