The robot fish was fitted with a twisted and coiled polymer (TCP) to drive it ahead, a light-weight, low-cost machine that depends on temperature change to generate motion, limiting its velocity.
Robotic fish. Picture credit score: Tsam Lung You
A TCP contracts like muscle mass when heated, changing the vitality into mechanical movement. The TCP used on this work is warmed by Joule heating – the present cross by means of {an electrical} conductor produces thermal vitality and heats up the conductor. By minimising the gap between the TCP on one facet of the robotic fish and the spring on the opposite, this prompts the fin on the rear, enabling the robotic fish to achieve new speeds. The undulating flapping of its rear fin was measured at a frequency of 2Hz, two waves per second. The frequency of the electrical present is identical because the frequency of tail flap.
The findings, printed on the sixth IEEE-RAS Worldwide Convention on Comfortable Robotics (RoboSoft 2023), present a brand new path to elevating the actuation – the motion of inflicting a machine or machine to function – frequency of TCPs by means of thermomechanical design and reveals the potential of utilizing TCPs at excessive frequency in aqueous environments.
Lead writer Tsam Lung You from Bristol’s Department of Engineering Mathematics mentioned: “Twisted and coiled polymer (TCP) actuator is a promising novel actuator, exhibiting enticing properties of sunshine weight, low-cost excessive vitality density and easy fabrication course of.
“They are often created from very simply assessable supplies corresponding to a fishing line they usually contract and supply linear actuation when heated up. Nonetheless, due to the time wanted for warmth dissipation in the course of the rest section, this makes them sluggish.”
By optimising the structural design of the TCP-spring antagonistic muscle pair and bringing their anchor factors nearer collectively, it allowed the posterior fin to swing at a bigger angle for a similar quantity of TCP actuation.
Though this requires better power, TCP is a robust actuator with excessive work vitality density, and might nonetheless drive the fin.
Till now, TCPs have been principally used for purposes corresponding to wearable gadgets and robotic palms. This work opens up extra areas of software the place TCP can be utilized, corresponding to marine robots for underwater exploration and monitoring.
Tsam Lung You added: “Our robotic fish swam on the quickest actuation frequency present in an actual TCP software and in addition the best locomotion velocity of a TCP software to date.
“That is actually thrilling because it opens up extra alternatives of TCP software in numerous areas.”
The workforce now plan to broaden the dimensions and develop a knife fish-inspired TCP-driven ribbon fin robotic that may swim agilely in water.
Supply: University of Bristol
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