The GMD-Snake - Real-Time Scheduling of a Flexible Robot Application at Run-Time

This paper presents the control software for the GMDSnake, a highly flexible robot prototype. The GMD-Snake is a configurable robot consisting of a number a equal sections, physically plugged together and electrically connected via an industrial field bus (CAN-bus). Its control software can be seen as individual tools supporting the design and implementation of dynamic distributed real-time applications. Based on an object-oriented programming model, it mainly comprises off-line program analysis tools, and a run-time executive consisting of an on-line monitoring component and an on-line scheduler. All tools can be implemented on top of an off-the-shelf real-time operating system, e.g. VxWorks. This paper describes in more detail the scheduling concept applied to control the GMD-Snake. Since the movement of this snake is highly dependent of the actual position and environment, also the characteristics of the respective control operations and their timing behaviour will vary during run-time. Our approach allows to reserve at run-time, i.e. when they are needed, the necessary resources, and release them after the termination of the respective operations. First results and experiences are discussed.