Facilitating cooperative AUV missions: experimental results with an acoustic knowledge-sharing framework

We describe and experimentally evaluate a decentralised world model for sharing data over limited bandwidth and high loss channels, such as encountered in the underwater domain. This world model service enables information extracted from the environment to be stored and queried using an ontology format. Besides providing an information storage facility, the world model manages all acoustic communications, and ensures that the shared ontology is updated on all robots while minimising transmissions. Using this world model service, a collaborative mission scenario of mine counter-measures is described, where the world model aids in the efficient use of the broadcast medium. Inwater experiments conducted in Loch Earn, Scotland, confirmed that the world model functioned correctly with a team of two AUVs. Early results for the efficiency of the system are also presented, which show that the world model can continue to function at relatively high packet error rates, although the error rate increased rapidly with transmission distance in our test environment.