Acoustic, Communication, Navigation And Sensing Systems For A Biologically-based Controller For A Shallow Water Walking Machine

Underwater robots must be in communication with engineers and scientists who are controlling their activities, and it is also necessary to know the location of the robot. Hard wire communication systems and optical sensors have specific problems when used in the ocean environment. Long cables can become tangled or cut and provide a great deal of drag to the underwater robot, and optical sensing systems become ineffective in murky water, We have been developing several acoustical concepts to solve these problems. Communication is to be performed by an ultrasonic data link, and an ultrasonic transponder system is utilized providing navigation information to the robot. We have performed preliminary experiments with these concepts in a lobster multichannel sonar biotelemetry system which is under development at Northeaster University's Marine Science Center. Muscular activity of lobsters is being monitored and we telemeter information concerning the activity of several muscles to the ocean surface via a unique acoustic data link operating over the frequency range of 30 kHz to 40 kHz. This acoustic system has also been successfully tested in the ocean to provide accurate navigation information when used in conjunction with moored transponders. In addition to communication and navigation, a specialized high-resolution sonar system is under development, which will allow the walking robot to obtain high-resolution acoustic images of all objects on the ocean floor and in the water column around it.