In a multiprocessor system-on-chip (MPSoC) private caches introduce the cache coherence problem. Here, we target at heterogeneous MPSoCs with a network-on-chip (NoC). Existing hardware cache coherence protocols are less suitable for MPSoCs because many off-the-shelf processors used in MPSoCs do not support these protocols. Furthermore, these protocols typically rely on global visibility and serialization of writes which does not match well with the parallel pointto-point communication provided by a NoC. Therefore, we propose a software cache coherence protocol, which can be applied in a heterogeneous MPSoC with a NoC. The software cache coherence protocol relies on explicit synchronization in the software. More specifically, caches are guaranteed to be coherent according to the Release Consistency model, on top of which we have implemented the standard Pthreads communication library. Heterogeneous MPSoCs with off-the-shelf processors can easily be supported, because processors are only required to provide cache control operations, e.g., clean and invalidate. All cache coherence operations are interruptible and do not impact the execution of tasks on other processors, therefore this protocol is suitable for predictable MPSoCs. Our software cache coherence protocol is implemented on an ARM926EJ-S MPSoC which is mapped on an FPGA. From experiments we conclude that the protocol overhead is low for the applications taken from the SPLASH-2 benchmark set. For these applications we observed a speedup between 1.89 and 2.01 on the two processor MPSoC.

This article describes “WAMbot,'' an autonomous unmanned ground vehicle and the Team MAGICian solution to the 2010 Multi Autonomous Ground‐robotic International Challenge (MAGIC). The system architecture, hardware, sensing, planning, navigation, mapping systems, and user interface were specifically designed to address the demands of the large‐scale distributed reconnaissance and surveillance task presented in the challenge. The resulting system was selected as a finalist and ultimately placed 4th in MAGIC 2010. © 2012 Wiley Periodicals, Inc.

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Simulation is an essential early evaluation tool for mobile robot research and development, and different stages of development have individual simulator needs. In this paper, we document details of two simulation tools that were developed for an entry into the MAGIC 2010 challenge, an autonomous ground vehicle competition. In developing the entry, simulators were used in two domains: problem analysis and solution testing. The problem analysis simulator was built using a commercial 3D game engine, whilst the simulator aimed at testing of the solution was built using a standard robotics library. By leveraging existing technologies appropriate for each domain, the task of simulator construction was simplified. The split allowed problem exploration independent of selected hardware, allowing for early simulation. These simulators allowed a team composed mostly of part-time volunteers to construct a complex distributed, multi-robot system and proved essential to our team\u27s success in the MAGIC 2010 challenge