Research On Event-Triggered Control Of Spacecraft Formation Under Communication And Computation Resource Constraints

Micro-nano satellite formation flying is a technology that enables multiple micronano satellites to cooperate with each other to accomplish a certain task.Due to its low cost,short development cycle,high task efficiency and flexibility,this technology has drawn wide attention in the aerospace field.However,a major challenge for this technology is the formation control of micro-nano satellites,which have very limited communication and computation resources as a result of using low-cost electronic components.Most of the existing formation control algorithms are based on the assumption of sufficient communication and computation resources,which are not applicable to micro-nano satellite formation.To address this problem,this paper adopts “event-triggered mechanism”as the theoretical tool and conducts in-depth research on the attitude and orbit formation control methods of multi-spacecraft that have limited communication and computation resources.The main contributions of this paper are summarized as follows:A robust formation control scheme based on event-triggered communication is proposed for the six-degree-of-freedom spacecraft formation control problem under communication resource constraints.This scheme adopts a distributed event-triggered communication condition,which enables each spacecraft to communicate with its neighbors only when necessary,thus reducing the communication frequency and resource consumption?meanwhile,considering the influence of model uncertainties and external disturbance,a radial basis function(RBF)neural network is employed to online fit various uncertainties and disturbances of the system,enhancing the robustness and adaptability of the formation control system? and a distributed controller based on consensus algorithm is designed to achieve the six-degree-of-freedom spacecraft formation under the condition of global availability of desired state.In order to be closer to the practical situation,this paper further considers the scenario of local availability of desired state,and designs a distributed desired state observer based on event-triggered communication on the basis of the previous scheme to estimate the desired state of each spacecraft,so as to improve the formation performance.Simulation results show that the control algorithm based on event-triggered communication mode can effectively save spacecraft communication resources,while ensuring the formation accuracy and stability.An formation control scheme based on event-triggered neural network and eventtriggered controller is proposed for the six-degree-of-freedom spacecraft formation control problem under both communication and computation resource constraints.This scheme improves on the previous scheme by designing an event-triggered control condition,which enables each spacecraft to update its neural network output only when necessary,thus reducing its computation frequency and computation resource consumption? in order to further save computation recource,the event-triggered control condition and controller are improved to make entire controller become an event-triggered update mode.Simulation results show that the two event-triggered conditions can independently save communication and computation resources,and compared with the control scheme based on time-triggered mode,the control scheme in this paper can reduce both communication and computation resource utilization by more than 90%,while ensuring the formation accuracy and stability.An event-triggered formation control scheme is proposed for the six-degree-of-freedom spacecraft formation prescribed performance control problem under both communication and computation resource constraints.This scheme combines prescribed performance control method to design an desired state observer based on event-triggered communication,which enables the observer to converge to a preset steady-state region within a preset time? meanwhile,in order to solve the problem of neighbor state information lag caused by event-triggered communication,a filter is designed to reduce the error of desired velocity information? in addition,by combining prescribed performance control method,an event-trigger based controller is designed to successfully solve the problem of six-degreeof-freedom spacecraft formation with prescribed performance and improve the control accuracy of spacecraft formation under the premise that the controller update frequency is basically unchanged.Simulation results show that this paper’s control scheme can reduce convergence time and improve formation accuracy under both communication and computation resource constraints.In addition,this paper also evaluates relationship between spacecraft hardware resource utilization rate and formation accuracy by changing parameter values of event-triggered condition through comparative experiments,which provides some trade-off experience for engineers in project development.