British scientists have created a robot fish that may be used for exploration and monitoring in order to broaden the scope of human underwater investigation. The robot fish mimics the movement of an aquatic creature.
The scientists at the University of Bristol explained in a press release that the robot fish was fitted with a twisted and coiled polymer (TCP) to drive it forward, a light-weight, low-cost device that relies on temperature change to generate movement, which also limits its speed.
"A TCP works by contracting like muscles when heated, converting the energy into mechanical motion. The TCP used in this work is warmed by Joule heating: "The pass of current through an electrical conductor produces thermal energy and heats up the conductor."
The authors of the study further explain that by minimising the distance between the TCP on one side of the robot fish and the spring on the other, this activates the fin at the rear, enabling the robot fish to reach new speeds. The undulating flapping of its rear fin was measured at a frequency of 2 Hz, or two waves per second. The frequency of the electric current is the same as the frequency of the tail flap.
The findings, published at the 6th IEEE-RAS International Conference on Soft Robotics (RoboSoft 2023), provide a new route to raising the actuation (the action of causing a machine or device to operate) frequency of TCPs through thermomechanical design and show the possibility of using TCPs at high frequency in aqueous environments.
"Twisted and coiled polymer (TCP) actuator is a promising novel actuator, exhibiting attractive properties of light weight, low cost, high energy density, and a simple fabrication process." Lead author Tsam Lung You from Bristol's Department of Engineering Mathematics said.
"They can be made from very easily assessable materials, such as fishing line, and they contract and provide linear actuation when heated up." However, because of the time needed for heat dissipation during the relaxation phase, this makes them slow."
