Jianglong Yu

Distributed adaptive practical time-varying tracking control for second-order nonlinear multi-agent system using neural networks

Practical adaptive time-varying formation tracking problems for second-order nonlinear multi-agent systems are investigated using neural networks, where the time-varying formation tracking error can be arbitrarily small. Different from the previous work, the states of followers form a predefined time-varying formation while tracking the states of the leader with unknown control input. Besides, the dynamics of each agent has heterogeneous nonlinearity. Firstly, for the case where the control input of the leader is unknown, a nonlinear practical time-varying formation tracking protocol using adaptive neural networks is proposed which is constructed using only local neighboring information. Secondly, sufficient conditions for the second-order nonlinear multi-agent systems to achieve practical time-varying formation are presented, where a novel practical time-varying formation tracking feasibility condition is given. Thirdly, an approach is presented to design the control parameters for distributed practical formation tracking control protocol. The stability of the closed-loop system is proven by using the Lyapunov stability theory. Finally, simulation results are given to illustrate the effectiveness of the obtained results.

Distributed time-varying formation control for second-order nonlinear multi-agent systems based on observers

In this paper, time-varying formation analysis and design problems for second-order nonlinear multi-agent systems are studied using a distributed observer-based method. The formation in this paper can be specified by time-varying continuously differentiable vectors and the dynamics of each agent has nonlinearity. Firstly, a nonlinear time-varying formation control protocol is proposed based on the distributed observer. Then a nonsingular transformation matrix is constructed using the property of the Laplacian matrix. Sufficient conditions for the second-order nonlinear multi-agent systems to achieve time-varying formations are presented using only position feedback, where a description of the feasible time-varying formation set is given. Thirdly, an algorithm with three steps is proposed to design the distributed observer-based formation control protocol. By using the Lyapunov theory, the stability of the proposed algorithm is proven. Finally, a numerical example with five nonlinear agents is provided to demonstrate the effectiveness of the obtained results.

Time-varying formation tracking for high-order multi-agent systems with switching topologies and a leader of bounded unknown input

Abstract Time-varying formation tracking problems for high-order multi-agent systems with switching topologies are investigated. Different from the previous work, the states of the followers form a predefined time-varying formation while tracking the state of the leader with bounded unknown control input. Besides, the communication topology can be switching, and the dynamics of each agent can have nonlinearities. Firstly, a nonlinear time-varying formation tracking control protocol is presented which is constructed using only local neighboring information. Secondly, an algorithm with four steps is proposed to design the time-varying formation tracking protocol, where the time-varying formation tracking feasibility condition is introduced. Thirdly, by using the Lyapunov theory, the stability of the proposed algorithm is proven. It is proved that the high-order multi-agent system with switching topologies achieves the time-varying formation tracking if the feasibility condition holds and the dwell time is larger than a positive constant. Finally, a numerical example with six followers and one leader is given to demonstrate the effectiveness of the obtained results.

Practical time-varying formation tracking for high-order nonlinear multi-agent systems based on the distributed extended state observer

ABSTRACT Practical time-varying formation tracking analysis and design problems for high-order nonlinear multi-agent systems are investigated, where the time-varying formation tracking error is controlled within an arbitrarily small bound. The states of followers form a predefined time-varying formation while tracking the state of the leader with unknown control input. Besides, the dynamics of each agent has heterogeneous nonlinearity and disturbance. First, a distributed extended state observer is constructed to estimate the followers nonlinearity and disturbance, and the leaders unknown control input simultaneously. A protocol based on the distributed extended state observer is proposed. Second, sufficient conditions for the multi-agent systems to achieve the practical time-varying formation tracking under the protocol are presented by using the Lyapunov stability theory. Third, an approach is derived to design the proposed protocol by solving a linear matrix inequality. Finally, numerical simulation results are given to illustrate the effectiveness of the theoretical results.

Robust adaptive control for hypersonic gliding vehicles based on NESO

In the reentry stage, the hypersonic gliding vehicle (HGV) has the obvious characteristics like high-dynamic, large flight envelop, complex flight environment and so on. These features result in severe parameter uncertainties. In order to improve the attitude control performance in reentry stage, the sources of the uncertainty and the unknown parameters are analyzed. Then a robust adaptive controller is established to cope with the parameter uncertainty problems. Three parts are included in this control system, which are the nominal controller, the nonlinear extended state observer (NESO), and the compensation controller. The nominal controller is constructed by using the nonlinear dynamic inversion (NDI) method. NESO is introduced to estimate the unknown parameters. On the basis of the NESO, the compensation controller is built and used to eliminate the effects caused by the parameter uncertainty. The stability of designed robust adaptive controller is proven by using the Lyapunov theory. The nominal controller and compensation controller are used together to guarantee the tracking attitude performance of the HGV. The effectiveness and performance of obtained theoretical results are demonstrated by using a numerical example.

Integration control design for a semi-strapdown seeker missile

Semi-strapdown coordinator is located on the missile body. Because of the existence of the parasitic loop, the semi-strapdown coordinator stable tracking control loop is strongly coupled with the body attitude control loop. As a result, the stability and tracking performance of the coordinator is severely affected. To deal with the stability and tracking problem of the semi-strapdown coordinator, an integration control system is proposed. The control law is designed based on backstepping theory. By choosing an appropriate feedback gain, the stability and dynamic performance of the system can be ensured. Finally, the integration control system is verified by simulation. The results show that the integration controller can solve the coupling problem between the semi-strapdown coordinator stable control and the body attitude control. The designed system is stable and has a good dynamic convergence performance.