Modeling, Analysis And Validation Of The High Confident On Board Software For Small-size Unmanned Helicopter

Small-size unmanned helicopter is a kind of vertical take-off andlanding(VTOL) aircraft that controlled by wireless remote controlcommands or onboard software or the two both. Onboard software is animportant part of the small-size unmanned helicopter, which carries themain function of running and managing the real-time tasks onboard. Thesereal-time tasks refer to flight control, helicopter and ground stationcommunication, sensor data acquisition and processing, device driving andso on. These real-time tasks have various running environments andreal-time requirements, and there are complex dependencies among thesetasks. And different tasks have different influences on the flight safety anddata integrity of the small-size unmanned helicopter. When some tasksrelated to flight safety are delayed or missed, it may lead to the collapse ofonboard software, or even made the small-size unmanned helicopter out ofcontrol. Therefore, studying the schedulability of onboard software in anenvironment with limited resources, complex dependencies and highreal-time requirements like the small-size unmanned helicopter, toestablish a high confident onboard software to enhance helicopter safetyand guarantee the running result predictable is very important.Based on the previous helicopter onboard software research, theonboard software tasks were defined and the onboard software task modelshave been established, and the real-time task constraints, dependenciesamong tasks and task safety degrees were analyzed. Through establishingand improving the onboard software task scheduling algorithm, theonboard software safety and result predictability has been enhanced.The main research work and achievements of this thesis are as follows:(1) Through analyzing the task requirements of small-size unmannedhelicopter onboard software, the task definition and task model ofsmall-size unmanned helicopter onboard software was established.(2) The small-size unmanned helicopter onboard software model wasanalyzed, the task scheduling algorithm under the condition of multipletask periods and multiple task dependencies was presented, and thelimitations of the algorithm and problems may exist were analyzed.(3) The task definition and task model of small-size unmannedhelicopter onboard software was improved, the task dependencies wererefined, attributes that descript task safety degrees were added, the tasksunder the new task definition were classified and a new algorithm thatenhances the onboard software credibility was presented. The problemsmentioned in paragraph (2) were solved by the algorithm, experimentswere carried out to prove the correctness of the algorithm.(4) Two schemes were proposed to solve the problem when systemresources cannot satisfy the onboard software safety demands. One schemedecreases some of the task safety degrees and the other applies multipleprocessors.The task management and scheduling algorithm designed in thispaper has greatly enhanced the safety of small-size unmanned helicopteronboard software system. The method that enhancing the real-time controlsystem safety through adding software task safety attributes has significantvalue of reference.