The goal of the AquaSWARM project is to design and develop small, energy-efficient, autonomous underwater robots as sensor-rich platforms for dynamic, long-duration monitoring of aquatic environments. A novel concept of gliding robotic fish is investigated, which merges the energy-efficient design of underwater glider with the high maneuverability of robotic fish. Gliding motion, enabled by pitch and buoyancy control, is exploited to realize dive/ascent and large-distance horizontal travel. Soft actuation materials-based flexible tail fins are used to achieve maneuvers with high hydrodynamic efficiency. The research is focused on understanding gliding design for small robotic fish, and addressing the energy efficiency issue from a systems perspective. Schools of such autonomous robots are deployed in lakes at the Michigan State University Kellogg Biological Station to detect harmful algal blooms (HABs) and validate models for HAB dynamics.
The project is expected to result in cost-effective, underwater robots that can perform uninterrupted, long-duration (several months), long-travel (hundreds of miles) operation in aquatic environments. This will provide a novel, viable, versatile, cyber-physical infrastructure for aquatic environmental monitoring, with applications ranging from understanding the impact of global warming, to environmental protection, drinking water reservoir safety, and seaport security. The project also offers an interdisciplinary training environment for graduate and undergraduate students, and provides outreach opportunities to inspire pre-college students and train highly qualified teachers. Robotic fish-based HAB detection will also be used as a tool to engage communities at local lakes and stimulate their interest in novel technology and environmental issues.
The goal of this award was to design and develop a new cost-effective underwater robot, called gliding robotic fish, as a mobile sensor platform for various aquatic environments. The robot integrates the features of both underwater glider and robotic fish to achieve energy-efficient locomotion and high maneuverability, enabling the robot to work continuously in the field for long durations while effectively counteracting the disturbances from currents, winds, and turbulences. A prototype of gliding robotic fish, named ``GRACE" (for Gliding-Robot-ACE), has been successfully designed, implemented, and demonstrated. The robot has a sliding mechanism that moves the battery pack back and forth to shift its center of gravity, which, when working in tandem with a pumping system, initiates the gliding motion. It has a servomotor-actuated tail that enables swimming. The project has resulted in mathematical models for describing the locomotion behavior of the robot. In particular, a novel energy-efficient spiral motion, produced by gliding with a deflected tail, has been examined both analytically and experimentally. In addition, feedback control algorithms have been developed for the gliding robotic fish to stabilize rectilinear gliding, track a trajectory with spiral motion, and sample multiple water columns. These algorithms have been tested experimentally in swimming pools and in inland lakes. The developed gliding robotic fish has been field-tested for several potential applications. One test involved sampling the crude oil concentration in the Kalamazoo River, Michigan, near the site of 2010 Enbridge oil spill. As another example, the robot was deployed in the Wintergreen Lake, Michigan, to sample the harmful algae and temperature distributions along twenty water columns. These data, which are prohibitively expensive to gather with traditional means, have shown strong spatial heterogeneity of harmful algal blooms (HABs) along both vertical and horizontal directions. These results have indicated strong promise of the developed technology in monitoring and understanding aquatic processes such as HABs. In addition to publications in archival journals and conference proceedings, the project has resulted in a patent application. With new funding from the National Science Foundation and other sources, commercialization efforts are underway to take the gliding robotic fish technology to the marketplace. Ultimately, the technology can benefit various applications, such as drinking water safety, port and maritime security, underwater infrastructure inspection, and ecological system monitoring. The project has also provided opportunities for the training of a number of graduate students, undergrad students, and K-12 teachers. Finally, it has enabled various activities for outreaching to K-12 students and the general public through lectures and robot demonstrations. Examples of such activities include exhibits at the 2010 and 2012 US Science and Engineering Festivals, 2014 MSU Science Festival, and 2014 Metro Detroit Youth Day.
