The Research Of An Operation System Of Spatial Robot Based On μC/OS-Ⅱ

With the development of space technology, space robots become more and more widely used in fields such as building and maintaining of space stations, recovering, releasing and maintaining of satellites of which the requirements is growing day after day. Unlike the situation on the ground, the special environment in the space requires an operating system with higher performance of real-time responding, stability and reliability. At the same time, due to the considerations of size and cost, the design and implementation of the operation system on a space robot is much different from the common used embedded system. Therefore, it is important to analyze the working conditions of the space robots and build a new kind of embedded operation system used on satellite payload which with higher performance of real-time responding, stability and reliability with the support of multi-task operation.This article first gives a detailed description of the characteristics and needs of Operating system on satellite. The differences of current popular embedded systems have been studied and compared. Furthermore, theμC/OS- II real-time operating system is Introduced. Its architecture has been analyzed. At the same time, some inadequacies of theμC/OS- II operating system have been investegated, and the corresponding improvement methodshave been proposed.1) For the Task scheduling algorithm of the operating system, Improvements on the priority inversion suppression have been made the priority limit algorithm is used in the former kernel. Priority inheritance strategy and a Round-Robin Scheduling algorithm have been used. 2) For the requirement of real-time responding of operating system, improvements have been made to the interrupt and timing modules. The adjustable timer resolution (ATR) module has been added. The former kernel employs traditional ways of cyclical clock interrupt service (ISR), which will check whether there is a cyclical high-priority task needs to be scheduled periodically. This will result in unnecessary Interruptions. If ATR algorithm is used, it can prevent these interruptions, and make improvements on the performances of theμC/OS- II in the microsecond level.3) For the reliability issues of the operating system, such as memory allocation efficiency, memory fragmentation and so on, the two-level segregated fit (TLSF) algorithm has been applied here.Finally ,The experiments of the new methods has been made based on the target platform using the EV40 developing board with an ARM processor, the analyzing results demonstrated that the new methods is effectively working. The main indicators of space robot operating system's performance were tested. The results prove its feasibility.