A semi-real-time scheduler for service robot components on Windows NT systems

Recently, interest in service robots has been increasing in academia and industry, but the diversity of robot systems and the breadth of expertise required for them hinder progress in robot development. To overcome these challenges, many robot software frameworks have been proposed to enable code reuse and division of development efforts. However, the existing robot frameworks assume general, non-real-time operating system environment and pay little attention to real-time support, which is one of the vital requirements for service robots since they run realtime as well as non-real-time applications. This paper proposes a user mode scheduler of periodic real-time components on unmodified Window NT operating systems on which most service robots are built. The proposed scheduler uses real-time characteristics of the general purpose Windows NT: OS timer resolution control, a high resolution multimedia timer, and minimal realtime priority support. The performance limits of the scheduler are examined by measuring the influence of the kernel mode operation. The DC motor PID control experiment result demonstrates that our proposed scheduler can achieve 10 ms period component executions with 20% accuracy.