An IEEE-1394 Based Real-time Robot Control System for Efficient Controlling of Humanoids

Modern sophisticated robots, e.g. humanoids, require significant real-time communication speed in their fieldbuses. Several existing field-bus technologies, like controller area network (CAN), Profibus etc., provide real-time performance and reliability, however the bandwidth is not enough to support the communication demand of the complex humanoids. In this research, we have addressed this critical issue by utilizing comparatively faster IEEE 1394 serial bus on commercial off-the-shelf hardware and Linux-based real-time software platforms. Since the lack of user-level communication protocols in IEEE 1394 standard is a major obstacle for designing a IEEE 1394 based control system, we have solved this issue by customizing the predefined IEEE 1394 packet formats. Moreover, various IEEE 1394 serial bus related features have been investigated for designing an efficient humanoid control system. In this work, we have followed the real-time modeling and analysis method using Unified Modeling Language (UML). A use case driven analysis of timing requirement and determination of real-time constrain have been shown to prove the usefulness of our approach. The ongoing implementation of this proposed system in our network based humanoid, MAHRU, has been demonstrated in both commercial RTOS RTLinux (Pro) and free OSS RTOS Xenomai. The performance measurement of basic IEEE 1394 read transaction has been shown in both platforms along with a comparison with similar experiment on CAN bus. This provides an estimation of performance improvement of a humanoid control system on IEEE 1394 serial bus over CAN bus. Moreover the results obtained from two different Linux-based RTOS platforms indicate their relative pros and cons. This also enables us to select the suitable real-time framework for designing an efficient IEEE 1394 based humanoid control system