Robohub.org
 

Robot fish makes splash with motion breakthrough

by
01 May 2023



share this:

Robot fish. Image credit: Tsam Lung You

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. 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 2Hz, two waves per second. The frequency of the electric current is the same as the frequency of 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 shows the possibility of using TCPs at high frequency in aqueous environments.

Lead author Tsam Lung You from Bristol’s Department of Engineering Mathematics said: “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.

“They can be made from very easily assessable 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.”

By optimising the structural design of the TCP-spring antagonistic muscle pair and bringing their anchor points closer together, it allowed the posterior fin to swing at a larger angle for the same amount of TCP actuation.

Antagonistic muscles. Image credit: Tsam Lung You

Although this requires greater force, TCP is a strong actuator with high work energy density, and is still able to drive the fin.

Until now, TCPs have been mostly used for applications such as wearable devices and robotic hands. This work opens up more areas of application where TCP can be used, such as marine robots for underwater exploration and monitoring.

Tsam Lung You added: “Our robotic fish swam at the fastest actuation frequency found in a real TCP application and also the highest locomotion speed of a TCP application so far.

“This is really exciting as it opens up more opportunities of TCP application in different areas.”

The team now plan to expand the scale and develop a knifefish-inspired TCP-driven ribbon fin robot that can swim agilely in water.




University of Bristol is one of the most popular and successful universities in the UK.
University of Bristol is one of the most popular and successful universities in the UK.





Related posts :



Robot Talk Episode 92 – Gisela Reyes-Cruz

In the latest episode of the Robot Talk podcast, Claire chatted to Gisela Reyes-Cruz from the University of Nottingham about how humans interact with, trust and accept robots.
04 October 2024, by

Robot Talk Episode 91 – John Leonard

In the latest episode of the Robot Talk podcast, Claire chatted to John Leonard from Massachusetts Institute of Technology about autonomous navigation for underwater vehicles and self-driving cars. 
27 September 2024, by

Interview with Jerry Tan: Service robot development for education

We find out about the Jupiter2 platform and how it can be used in educational settings.
18 September 2024, by

#RoboCup2024 – daily digest: 21 July

In the last of our digests, we report on the closing day of competitions in Eindhoven.
21 July 2024, by and

#RoboCup2024 – daily digest: 20 July

In the second of our daily round-ups, we bring you a taste of the action from Eindhoven.
20 July 2024, by and

#RoboCup2024 – daily digest: 19 July

Welcome to the first of our daily round-ups from RoboCup2024 in Eindhoven.
19 July 2024, by and





Robohub is supported by:




Would you like to learn how to tell impactful stories about your robot or AI system?


scicomm
training the next generation of science communicators in robotics & AI


©2024 - Association for the Understanding of Artificial Intelligence


 












©2021 - ROBOTS Association