Mobile sensors

Autonomous exploration in a dynamic environment
Flood waters near the coastal town of Sendai, Japan, after the earthquake and tsunami that devastated the region.

The tsunami that struck Japan on March 11, 2011. Missing Malaysia Airlines flight MH37. Both show the critical need for robots capable of working together as a mobile sensor network in a highly dynamic, potentially hazardous environment.

Nina Mahmoudian wants to increase the effectiveness of the response by robots to environmental and human disasters. Her goal: to develop tools and algorithms that lower deployment and operating costs, increase efficiency and boost endurance for missions with a high level of complexity, including coastal surveillance, subsea structural inspection, hazards detection, and rescue and relief.

“What is really needed for search missions that require vast underwater inspection and detection, such as locating boats and aircrafts at sea, is an underwater robot that can explore an area with a sense of what it is looking for,” says Mahmoudian. Even better: A fleet of underwater robots. “In contrast to the use of a single vehicle, multi-robot systems could vastly increase mission area, decrease operation time, and offer a diverse suite of sensors, system resiliency, and goal redundancy,” she adds.

Mahmoudian and her research team at the Michigan Tech Nonlinear and Autonomous System Laboratory are building four such robots: low-cost autonomous underwater vehicles (AUVs), each weighing about twenty-five pounds. Named ROUGHIE (for Research Oriented Underwater Glider for Hands-On Investigative Engineering) Mahmoudian’s AUVs sport better, more powerful brains equipped with multi-agent motion control algorithms and tools for more efficient underwater discovery. They are also modular, allowing users to swap out different components depending on what tasks the AUVs undertake.

Powered only by batteries, ROUGHIEs “fly” slowly through the water simply by adjusting their buoyancy and weight. “They are designed for use near the water’s edge, which offers a special challenge,” adds Mahmoudian. “ROUGHIEs will come up on the coast, which means they have to operate where there’s lots of traffic and noise.”

ROUGHIEs are also less expensive than commercial gliders. “At a fraction of the cost of one commercial vehicle, it is possible for us to test glider swarm algorithms and compare them to established single glider models,” she says. “Testing control methods for hazardous underwater zones such as ports, shipping channels, and reefs can be done without much financial risk.”

Mahmoudian’s work combines fundamental and applied research. “One of our goals is to facilitate a seamless transition between academic modeling/simulation problem-solving approaches and real-world applications.”