Fighting climate change with a soft, robotic fish

Fighting climate change with a soft, robotic fish

Growing up in Rhode Island (Ocean State), I lived near the water. Over the years, I’ve seen the effects of rising sea levels and rapid erosion. The tide has slowly washed away entire homes and beaches. I have witnessed firsthand how rapidly climate change is altering the ocean ecosystem. Sometimes I feel overwhelmed by the impossibility of climate change. What can we do in the face of such a global dilemma that is almost incomprehensible? The only way I can overcome this perception is by committing to doing something in my life to help, even if it’s in a small way. I think with such a big problem, the only way forward is to start small, identify one niche I can work in, and see how I can shape my research around solving that challenge.

One of the main challenges is the rapidly rising global ocean temperature. When scientists look to make climate correlations using temperature data, they generally use constant temperature recorders attached to buoys or on the ocean floor. Unfortunately, this approach reduces the area between the ocean’s surface and its floor. The changing conditions of the oceans create microclimates, pockets of the ocean that are not affected by general climate trends. Scientists have shown that most organisms experience climate change through these microclimates. Fish are greatly affected by this rapid increase in temperature as they can only lay eggs in a lower temperature range. Climates change temperature quickly. Thus, many species cannot adapt quickly enough to survive. At this rate, 60% of fish species could become extinct by the year 2100.

Of course, fish are not the only organisms affected by the rapid increase in temperature. Corals in the Great Barrier Reef can only survive in minimal temperatures, and as the temperature rises, corals suffer mass coral bleaching. AIMS, the Australian Institute of Marine Sciences, the government agency that monitors the Great Barrier Reef, uses divers towed behind boats to record reef observations and collect data. Unfortunately, this has resulted in some casualties due to shark attacks. They are beginning to deploy large gliders about seven feet long that can mitigate this danger. These robots come with a hefty price tag of $125,000 to $500,000. They are also too big to navigate parts of the reef.

Our solution in the Soft Robotics Lab at Worcester Polytechnic Institute is to build a tether-free (no tether), biologically inspired robotic fish, funded in part by the National Science Foundation’s Future of Robots in the Workplace Research and Development Program. Our goal is for the robot to navigate the complex environment of the Great Barrier Reef and record dense 3D temperature data throughout the water column. Moreover, we will use non-hazardous and affordable materials for fish body. Since our motivation is to create a tool for use in climate research, a robot that is cheap and easy to manufacture will increase its effectiveness. Our approach is in stark contrast to traditional autonomous underwater vehicles that use noisy propellers and are inappropriate for life underwater. We chose to simulate the movement of real fish to reduce the environmental impact of our robot and enable close monitoring of other real fish.

We are of course not the first to create a robotic fish. In 1994, MIT produced RoboTuna, a fully rigid fish robot, and since then, there have been many different iterations of fish robots. Some are made out of completely solid materials like the RoboTuna and use motors that power the tail (back fin) that powers the fish. However, this does not replicate the fluid movement achieved by real fish while swimming. A possible solution is to use soft materials. Designs that use soft materials up to this point use a silicone tail, which is pneumatically or hydraulically actuated. Unfortunately, these robots cannot operate in harsh environments because any cuts or scratches in the silicone can cause system leaks and lead to complete failure of tail operation. Other robots have incorporated more durable rigid materials, running them with cables, then attaching a soft silicone tip that bends with the force of the water. All of these earlier robots are difficult to manufacture and require institutional know-how to recreate.

MIT robotona and MIT SOFI robotics

We’ve created a cable-powered 3D-printed wavy springy tail made of soft materials that can pilot a small robot fish. The wave spring gives the robot its biologically inspired shape, but it can bend as smoothly as silicon-based robots and real fish. The wave spring is 3D printed entirely from an affordable and easy to use flexible material. This material and method creates a robot that is extremely soft yet durable, withstands rough treatment, and operates for hundreds of thousands of cycles without any degradation of any of the robot’s systems. The robot distinguishes itself by being easy to assemble, with only a few parts, most of which can be 3D printed.

The wave spring itself has a biologically inspired design. Reef fish are morphologically diverse but share a similar body shape that we mimic with a tapered oval design. The wave spring itself consists of a network of diamond-shaped cells that can both be compressed and bent. To restrict our robot to lateral bending only, we added struts below the dorsal and ventral edges of the wave spring.

With this design, we have successfully created a robotic fish. The robot can swim freely in fish tank, swimming pool and lake. While testing the fish in these environments, we found that the speed and performance of our bot was comparable to other fish bots running to similar standards. In order for the robot to be waterproof (to protect the electronics required for untethered swimming), we had to add latex skin. This increases the manufacturing complexity of the design, so we will investigate not only optimizing the robot’s performance, but also designing it to ensure a streamlined, high-performance robot.

Most importantly, we will add the sensors required to collect data such as temperature, which is essential for a better understanding of the rapidly changing local climates in the oceans. It is critical that we stay focused on this goal, as it drives not only the design of the robot, but our motivation for doing the work. Climate change is the number one crisis our world faces. I encourage everyone to connect their interests and work, no matter the field, in some way to this cause because we are the only ones who can do something about it.

tags: Vitality inspiredAnd the C- Research innovation

Robin Hall is a PhD candidate from Worcester Polytechnic Institute.

Robin Hall is a PhD candidate from Worcester Polytechnic Institute.

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