Simultaneous Localization And Elliptical Circumnavigation Of Multi-targets Based On The Collaboration Of Multi-agents

A non-cooperative target is a target that cannot actively provide effective cooperation information such as location,velocity and distance.What are included in this kind of target are wide,such as a moving robot or a region.The problem of simultaneous localization and circumnavigation of these targets based on the multi-agents system is a basic problem faced by many fields.For example,in the field of military reconnaissance,our aircraft needs to accurately estimate the position of the hostile targets,and then monitor the targets and collect data outside the warning area.In the field of natural disasters,our aircrafts often need to accurately estimate the position of the disaster area,and then surround the area to send the complete information on the scene back to the command center.Thus,this problem has aroused widespread attention from many scholars.As a passive measurement technology,simultaneous localization and circumnavigation based on bearing measurements is a more advanced than the technology based on distance measurements.All current algorithms can only make the agent circumnavigate the target on a circle.However,in practical applications,when planning a circumnavigation trajectory,the agents are often affected by obstacles distributed around the targets and the warning area of the targets,so that they can no longer circumnavigate the targets on a circle.Therefore,how to design a more general circumnavigation trajectory to adapt to the more complex environment is very urgent and important.This paper studies the problem of simultaneous localization and elliptical circumnavigation of the multi-targets by the multi-agents,and proposes a more general control strategy for the elliptical circumnavigation trajectory.The convergence of the whole system is analyzed by using persistent excitation theory,stability analysis theory,graph theory,consensus theory and other related theories.In addition,in practical applications,the problem of time synchronization is inevitable in multi-agents system.And the smaller the synchronization error,the better the effect of simultaneous localization and circumnavigation.Therefore,we propose a distributed time synchronization algorithm,and verify the superiority and feasibility of the algorithm on the self-designed hardware platform.The main work is as follows.1.We discuss the problem of simultaneous localization and general elliptical circumnavigation guided by the non-cooperative targets.In order to enable the multi-agents system to circumnavigate the multi-targets in more complex environment,this paper proposes an elliptical circumnavigation controller by only employing bearing measurements without knowing the target's position and velocity.Then,the stability of the whole system is analyzed and proved under the two cases of the stationary targets and the dynamic targets.And we derives the value conditions of some parameters in the two cases.When these conditions are met,the algorithm proposed in this paper can force the multi-agents system to locate and elliptically circumnavigate the multi-targets in a general way.Finally,a series of numerical simulations are presented to verify the correctness of the theoretical analysis and the effectiveness of the algorithm.2.We consider the problem of simultaneous localization and elliptical formation circumnavigation guided by the non-cooperative targets.First of all,a new geometric center estimator is first established,only needing to use local information in gain design rather than any specific initialization.In the gain design,neither is the global information of some variables from all agents needed,nor is the gain needed to be designed large enough.For the two cases of the stationary targets and the dynamic targets,a unified circumnavigation controller is also designed instead of designing corresponding controllers for different cases.And we prove that when some parameters are reasonable,even for the dynamic targets,the system can drive all agents to circumnavigate each target in desired formation on a desired elliptical trajectory centered at the geometric center of the targets.Finally,a series of simulations are conducted to verify the validity and correctness of the algorithm.3.A distributed time synchronization system is designed to provide accurate timing service for the multi-agents system.When the multi-agents simultaneously locate and elliptically circumnavigate the multi-targets,they need to exchange information to collaboratively estimate the geometric center of the targets and linear velocity of the agents with formation circumnavigation.In actual work,due to the influence of random communication delay,when the information is exchanged between the agents,the problem of time synchronization is inevitable.And the larger the synchronization error,the worse the effect of simultaneous localization and circumnavigation.To solve this problem,we first propose a Delay Compensation Based Time Synchronization(DCBTS).Then,with FPGA(Field Programmable Gate Array)as the control chip,a hardware physical platform of distributed time synchronization system is designed.On this platform,the most popular distributed time synchronization algorithms are compared systematically.The experimental results show that the DCBTS algorithm not only ensures that the drift estimate converges at a rate of 1/k(where k is the discrete time)and the offset estimate does not accumulate for a long time,but the compensation mechanism can effectively compensate the delay and then greatly reducing the synchronization error between nodes.In addition,based on the DCBTS algorithm,the method of “synchronous second pulse(SSP)+ synchronization time(ST)” is designed to provide timing service,which makes the timing protocol very simple,and it's also convenient for the time acquisition for the underlying hardware.