Robotic fish demos new motion for the ocean

The Bristol team equipped their robot fish with a twisted and coiled polymer (TCP), a light-weight low-cost device that uses temperature change to generate movement, contracting like a muscle when an electrical current is applied. 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.

“Twisted and coiled polymer (TCP) actuator is a promising novel actuator, exhibiting attractive properties of light weight, low-cost high energy density and simple fabrication process,” said Lead author Tsam Lung You from Bristol’s Department of Engineering Mathematics.

“They can be made from very easily accessible materials such as a 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.”