An Unmanned Aerial Vehicle Safety Control System Based On Embeded Realtime Operating System

With the developing of the MEMS,the small quadrotor drone technique has rapidly entered civil domain and commercial field because of flexibility,and it has been rapidly applied in many aspects such as movie shooting,power inspection,and disaster relief.However due to the complexity of drone system,low technical barriers for consumers,and incomplete regulatory law,etc.The accidents caused by the drone occurs frequently,which poses great risks to people's lives and property.This paper focuses on the current status of the small quadrotor drone system and uses the “Research of a New Generation of Small UVA Safe Flight Control System” project of the Shenzhen International Cooperation Project to develop a small quadrotor drone flight control system based on the trusted embedded operating system with the cooperation of the partner Flint group at Yale University,aims to improve the reliability and safety of the small quadrotor drone.This system based on the trusted operating system which called Certi KOS-ARM kernel,and this drone system security architecture which based on Raspberry Pi3 development board has been rationally designed.All the driver codes and control algorithm codes related to the drone hardware platform have been rewritten according to the architecture.With a more streamlined and reasonable software structure,the attitude control system of the drone system has been implemented.Based on the demands of the drone system,the control system uses the multi-process scheduling mechanism has been designed and implemented.The interrupt mechanism and process scheduling algorithm of this system were improved and better to serve the drone system.For the reliability of process tasks,this paper introduces the formal verification method.Formal verification of the SPI bus driver which is the important part of the system driver.Because the most important reason for the loss of control of the drone is due to the flight controller execution timeout.The reasons of the delay of the flight control loop may be very difficult to eliminate.Therefore,we focus on the fault tolerance mechanism for process delay.The design,combined with the scheduling algorithm of the real-time operating system,innovatively proposes a fault handling module using process task scheduling and an emergency stop paddle module.Finally,in the experimental part of this paper,through the comparison of the flight test between single-process and multi-process flight systems,the influence of the formal verification of the SPI bus driver of the drone system,the multi-process aircraft fault recovery module and the emergency stop module flight test and static testing,these three experiments proves that the design and implementation of the quadrotor drone control system based on the trusted embedded real-time operating system can greatly improve and ensure the reliability and safety of the drone control system.