Extended RT-Component Framework for RT-Middleware

Modular component-based robot systems require not only an infrastructure for component management, but also scalability as well as real-time properties. Robot technology (RT)-middleware is a software platform for such component-based robot systems. Each component in the RT-Middleware, so-called "RT-component\´\´ supporting particular robot functions, is based on common object request broker architecture (CORBA). Unfortunately, the RT-Middleware lacks the mechanism for real-time control. In this paper, we extend the framework of the RT-Components to take care of timing constraints. We first enable tasks to have different periods within each RT-Component. We then modify the packet format of the General Inter-ORB Protocol (GIOP) to transfer the information of timing constraints over RT-Components. The performance evaluation on ART-Linux shows that the extended RT-Component framework improves the schedulability of distributed real-time tasks, without causing critical overheads in unmarshaling the modified GIOP packets.