Research On Formation Control Of Unmanned Surface Vehicles Under Complex Communication Conditions

Inspired by the swarm behaviors generated from real-world biological systems,the research on multi-agent systems has received tremendous attention and gradually become a frontier.Multiple unmanned surface vehicles,the special kind of multi-agent systems,are collected under a prescribed pattern with local interactions to execute certain missions that cannot be accomplished by a single vehicle,such as cooperative joint operation,underway replenishment and environment monitoring.Thanks to the development of distributed control theory and modern communication technology,the formation control of unmanned surface vehicles has been proposed and stirred up increasing research interest in theoretical and engineering communities.For a network of unmanned surface vehicles with respect to oceanic environmental disturbances,the kinematic and kinetic are modeled by taking into account the nonlinear and coupling dynamic characteristics.With consideration given to the communication conditions and uncertain parametric perturbations,a distributed control law consisting of locally-interacted information is designed by utilizing the methodology of nonfragile H∞ performance analysis so that the networked multiple unmanned surface vehicles can maintain the formation pattern within the leaderless consensus-based framework.In comparison to the existing scientific research on formation control of unmanned surface vehicles,the main contributions of this thesis are highlighted as follows:First,to overcome the disadvantages of certain formation strategies(e.g.,leader-follower strategy)with weak robustness and low scalability,a novel formation strategy is proposed on the basis of leaderless consistency regulation.By constructing a transformation,the complex dynamic characteristics of the kinematic and kinetic are promisingly simplified.The nonfragile control technique is exploited to recast the precise control design of unmanned surface vehicle with uncertain parametric perturbations into the nonfragile control design of that with precise parameters.In order to describe the global movement of the formation system,the concept of formation reference function is proposed,whose explicit expression with determined initial condition can be characterized by employing the newly-proposed orthogonal-transformation-based decomposition technique.Second,to study the effect of the time-varying network interaction caused by the interruptions and reestablishments of communication channels,the research topic on formation control of multiple unmanned surface vehicles with topology switching is proposed.For the regulation of the switching modes,one introduces a switching signal.When the switching signal is chosen as a deterministic continuous-time function,the distributed control law is constructed by utilizing the information of deterministic switching topologies such that the resultant closed-loop formation error system preserves continuous-time switching dynamics.By suitably choosing the common Lyapunov-Krasovskii functional,a sufficient condition is derived to guarantee the existence of the desired control law.Another consideration is that the switching signal is generated from a right-continuous Markov process with completely known transition rates.To this regard,the Markovian jump parameter is involved in characterizing the distributed control law such that the resultant closed-loop formation error system can be regarded as a continuous-time Markovian jump system.Within the framework of stochastic stability analysis,the mean-square leaderless consistency is regulated by a sufficient condition.With introducing a group of free-connection weighting matrices,the derived result is extended to the case that the transition rates are partially known.Third,to study the effect of the interaction time-delay induced by the limited bandwidth and data transmission capability,one proposes the research topic on formation control design of multiple unmanned surface vehicles with communication delay.For the case that the communication delay is symbolized by a positive constant,the distributed control law is designed by a collection of local information from a network of in-neighboring unmanned surface vehicles with respect to transmission delay.Under the designed distributed control law,a continuous-time constant delay system is derived to model the resultant formation system.By employing the Lyapunov-Krasovskii stability analysis technique,one derives the delay-dependent condition for formation performance analysis of the networked unmanned surface vehicles.In order to specify the time-varying communication delay,a continuous-time function with lower and upper bounds is introduced.By taking advantage of the delay information for constructing the Lyapunov-Krasovskii functional,a sufficient condition is derived to coordinate the coupling between delay information and network structure so that the formation control of multiple unmanned surface vehicles with time-varying communication delay can be achieved.Fourth,to study the effect of the coexistence of time-varying network communication and data transmission delay caused by unrealistic interaction channels and unknown communication environment,the topic on cooperative formation control design of multiple unmanned surface vehicles with topology switching and communication delay is proposed.When the complex communication conditions are described by deterministic topology switching and constant communication delay,the convergence of the formation system is guaranteed by the delay-dependent condition with the aid of common Lyapunov-Krasovskii functional technique.For the case that the multiple unmanned surface vehicles interact under Markovian switching topologies with respect to time-varying communication delay,the resultant closed-loop formation error system is inherently regarded as a continuous-time Markov jump time-varying delay system.Furthermore,by considering that the communication delay switches among a set of continuous-time functions with respect to the topology switching modes,a distributed control law is designed by utilizing the Markovian topology switching characteristic and mode-dependent communication delay information.With suitably choosing a stochastic Lyapunov-Krasovskii functional,the existence of the desired control law is guaranteed by a sufficient condition.Fifth,to save the communication resource and reduce the energy consumption for the design of continuous-time formation controller,the sampled data transmission mechanism is promisingly exploited.With consideration given to the sampled-data formation control of multiple unmanned surface vehicles with topology switching,a distributed control law is constructed by utilizing the sampled local information from neighboring unmanned surface vehicles.In this regard,the resultant closed-loop formation error system consists of both the continuous-time component and the discrete-time component,which leads to the so-called hybrid system.The ’artificial time-delay’ technique is proposed to equivalently convert the discrete-time component into the continuous-time one so that the hybrid system can be encouragingly regarded as a continuous-time system with respect to time-varying delay.When designing the sampled-data control law for formation control of multiple unmanned surface vehicles with communication delay,the sampling interval and time-delay information are exploited to suitably construct the Lyapunov-Krasovskii functional for the asymptotic stability analysis of the reduce-order closed-loop formation error system.By considering the sampled-data formation control design of multiple unmanned surface vehicles under complex communication conditions,the Lyapunov-Krasovskii stability analysis technique is employed to characterize the interplay among sampling interval,time-delay information,topology switching mode and network structure characteristic,which plays an essential role in regulating the formation accuracy and robustness.