Engineers at the University of California-San Diego have created a squid-like robot for underwater exploration. The robot is untethered and can propel itself by using jets of water. It has also overcome electrical challenges, such as being able to carry sensors, specifically a camera.
Michael T. Tolley is one of the senior authors of the research and a professor in the Department of Mechanical and Aerospace Engineering at UC San Diego.
“Essentially, we recreated all the key features that squids use for high-speed swimming,” Tolley said. “This is the first untethered robot that can generate jet pulses for rapid locomotion like the squid and can achieve these jet pulses by changing its body shape, which improves swimming efficiency.”
The research was published in Bioinspiration and Biomimetics.
The Squid Robot
The squid-inspired robot consists of soft materials like acrylic polymer, as well as some more rigid, 3D printed and laser cut parts. Soft robots are safer for fish and coral when it comes to underwater exploration, as rigid robots could damage them. However, there is a downside. Soft robots are often slower and less efficient at maneuvering.
The research team was made up of roboticists and computer simulation experts. The group looked toward squids due to their ability to travel at fast speeds. The cephalopods achieve this speed through a jet propulsion mechanism.
Drawing inspiration from the squids, the team designed the robot so that it can take water into its body and store elastic energy in its skin and flexible ribs. The energy is then released by the robot compressing its body, resulting in a jet of water propelling the robot.
When it is not moving, the robot holds the shape of a paper lantern, and its ribs are flexible and act like springs. Each end of the robot has a circular plate where the ribs connect, with one being connected to a nozzle that takes in and ejects water. In order for the water to eject, the robot’s body must contract. The remaining plate is then used to hold sensors, such as a water-proof camera.
Testing the Robot
The squid robot was tested in Professor Geno Pawlak’s lab, which is located in the UC San Diego Department of Mechanical and Aerospace Engineering. Following those tests, it was sent out to the tanks at UC San Diego Birch Aquarium at the Scripps Institution of Oceanography.
The robot was able to be steered by adjusting the nozzle, and the waterproofing of electrical components, such as the battery and camera, proved to be successful. The device traveled at a speed of around 18 to 32 centimeters per second, which is about half a mile per hour. The speed is impressive, being faster than most soft robots.
Caleb Christianson, a senior medical devices engineer at Dexcom, led the study among the research group.
“After we were able to optimize the design of the robot so that it would swim in a tank in the lab, it was especially exciting to see that the robot was able to successfully swim in a large aquarium among coral and fish, demonstrating its feasibility for real-world applications,” Christianson said.
After testing various different models of the nozzle, the team finally found one to increase the robot’s efficiency, as well as make it maneuver and travel at faster speeds. One of the major contributing factors leading to that discovery was the simulation of the jet propulsion, which was led by Professor Qiang Zhu and his team in the Department of Structural Engineering at UC San Diego.