Safety Control And Simulation Of Unmanned Aerial Vehicle In Cyber-physical Systems

Cyber-Physical Systems（CPS）is a multi-dimensional complex system that integrates physical computing,network communication and automatic control.By embedding computing and communication into the physical process,it is highly integrated with the physical process,and then realize the deep cooperation within the system,so that the system can realize real-time perception,implement dynamic control and follow-up information services.At present,CPS has received extensive attention and research in academia.As one of the typical application scenarios of the current cyber-physical system,UAVs are also highly integrated with multiple functions such as automatic control,calculation,and network communication.They are widely used,but these functions increase the vulnerability of the system and reduce the ability to resist external attacks.Not only external disturbance attacks but also the possibility of their own physical failure must be considered in UAV system.Therefore,the system needs to have a certain fault tolerance to ensure that it can safely complete the tasks in these situations.With the expansion of UAV application scenarios and more diversified functions,the system will become more complex and therefore more vulnerable to cyber-attacks.Therefore,the UAV system needs to have the ability to maintain good control effects under a variety of cyber-attacks.In order to solve above problems,this thesis present the following research,the main contents include:（1）According to the characteristics of the fixed-wing UAV,a basic coordinate system is established,its dynamics and kinematics equations are derived,and the dynamics equations are linearized under typical flight conditions.the lateral dynamics equations and longitudinal dynamics equations are obtained,respectively.（2）Considering the possible software failure and physical failure of the UAV in the CPS system,a control framework is designed,which includes a high-performance controller（HPC）,a high-assurance controller（HAC）,a state monitor and switching logic.When the system is working normally,always ensure to use a high-performance controller to improve work efficiency.When the UAV system software fails or there is damage to physical components,the control effect of the high-performance controller will become worse.At this time,the controller will be switched from the high-performance controller to the high-assurance controller immediately to ensure the normal operation of the system.Based on the fixed-wing UAV dynamic model obtained in Chapter 2,the L₁ adaptive controller is designed as a high-assurance controller,and the MPC controller is designed as a high-performance controller.The control effect of the MPC controller and the L₁ adaptive controller is verified under different external conditions.Furthermore,the states monitor and switching logic are designed.The effectiveness of the proposed method is verified by numerical simulation.（3）Aiming at the problem of UAV suffer from cyber-attacks in CPS system,a hybrid robust controller is designed.There are several sub-controllers under the control framework,and each sub-controller is designed for a specific network attack strategy.In order to deal with the external attacks,the adjustment device performs real-time switching of the controllers according to the performance of different sub-controllers,ensuring that the control system always has a good control effect and the safety of the system.To verify the idea,the H₂-H_∞ hybrid robust controller was designed on the basis of the dynamic model of a small-unmanned helicopter.The simulation shows that the designed controller has better performance than the single optimal controller.