Science Tokyo first and third at JAMSTEC underwater robot competition
Two teams from the Aqua Lab from the Society for the Study of Robotics, an official Science Tokyo student club, emerged victorious at the Underwater Robot Convention in JAMSTEC 2025, held on August 23 and 24 at the facilities of the Japan Agency for Marine-Earth Science and Technology (JAMSTEC) in Yokosuka City, Kanagawa Prefecture.
Team A-Quadken won the Free Division competition, while Team AquaUMIUSI finished third in the Video Division competition.
The Underwater Robot Convention aims to broaden its network of participants through competitions and presentations featuring self-built underwater robots, provide opportunities to tackle real-world challenges using engineering knowledge and skills, and promote the enjoyment and importance of underwater robotics research.
Participants compete in four categories:
- Freestyle Division — Teams focus on original ideas and technologies utilized in underwater robots
- AI Challenge Division — Teams create algorithms applied to autonomously controlled robots that attempt to burst underwater balloons
- Video Division — Teams compete through videos showcasing their robot's technical content, originality, and performance
- Junior Division — Team made up of middle and high school students
Science Tokyo’s performance at this year’s competition was as follows.
Team A-Quadken — Freestyle Division winners
In the Free Division, teams competed for a maximum total of 100 points — 50 points for workshop presentations and 50 points for free performance abilities. This year, 17 teams applied, and 8 teams that passed the document screening participated.
QuadKen is an underwater robot inspired by cephalopods like octopuses. It moves by utilizing ballast tanks in its head, membranes stretched across its four legs, and thrusters located in its central section.
Ballast tanks are devices that adjust buoyancy by taking in external water into the body. Because it utilizes buoyancy, the robot can efficiently perform downward and upward movements compared to thrusters.
QuadKen is equipped with four ballast tanks. This allows it to control ascent and descent, as well as pitch rotation. By adjusting the positions of the center of gravity and center of buoyancy within the robot, it can also control roll rotation.
The primary movement of this robot combines membrane steering with thruster propulsion. It changes direction by moving its legs to alter the membrane's shape, thereby changing the direction of resistance from the water. Combined with assistance from the thrusters, this enables quick and dynamic movement.
Another strength is its ability to generate propulsion by scooping water with the membrane. For instance, in environments like ponds where using thrusters is difficult due to algae or sediment, it can opt for membrane-only movement, allowing selection of the most suitable locomotion method for the environment.
QuadKen is a robot that combines the characteristics of both conventional thruster-based underwater robots and robots using biologically inspired fins. Its key feature is the ability to switch between or combine high-output propulsion via thrusters and highly efficient, environmentally gentle propulsion via fins, depending on the environment and situation.
To enable intuitive control of this highly rotationally symmetric robot, accelerometers and other sensors are used, allowing the controller to operate the vehicle intuitively.
At the competition, this flexibility of movement and high operability, resulting in stable dynamic motion, along with the content presented during the first day's presentation, were highly evaluated.
Team AquaUMIUSI — Video Division 3rd-place finishers
UMIUSI is a robot equipped with four azimuth thrusters capable of thrust vectoring. Its defining feature is the ability to utilize more thrusters during movement compared to conventional underwater robots. By combining thrust from multiple thrusters, UMIUSI achieves high-power, high-efficiency movement with a high degree of freedom.
UMIUSI was constructed last year. Based on that design, the Science Tokyo team made significant improvements to the thruster components and circuitry, and decided to enter the Video Division competition.
Conventional robots suffer from issues such as complex and fragile thruster mechanisms and difficult-to-use electronic speed controllers (ESCs) for driving brushless motors, making precise rotation control impossible. This year, to solve these problems, the team simplified the thruster mechanism and developed its own ESCs for motor drive, achieving high efficiency through vector control. Furthermore, to reduce wiring, the team made each ESC self-contained and enabled connection to the main board via controller area network communication. This successfully reduced wiring and achieved miniaturization. Additionally, Team AquaUMIUSI enabled each ESC to drive servo motors and control status recognition LEDs that change color based on rotation speed and other factors. This also achieved modularization that can be utilized in other robots and a reduction in microcontroller boards.
Although UMIUSI is still under development, it was recognized for successfully implementing challenging attempts such as communication and the operation of thrusters and ESCs.
Comments from Team A-Quadken member
Satoshi Takatsuno, 3rd year, Mechanical Engineering Machinery Team
I was responsible for constructing the waterproof container and designing the vehicle's landing gear and thruster components. We faced numerous challenges, including the container's insufficient size, water ingress into the actuator portion during experiments, and vehicle control issues. However, through collaboration with team members, we successfully completed the robot. During the actual performance, we were able to operate the robot as originally planned on both runs. I am extremely pleased that Aqua Lab achieved its first victory at this convention. I would like to take this opportunity to express my deepest gratitude to the senior members who supported us and to all the organizers who provided us with this opportunity.
Comments from Team AquaUMIUSI member
Yoshiki Ikawa, 2nd year, Mechanical Engineering Circuit Team
I was part of the Circuit Team developing ESCs and other components. With only four members, progress was extremely challenging, but I am thrilled we managed to finish third. I feel a bit guilty for asking the team to push themselves so hard. For the second-year students, including myself, this was our first JAMSTEC competition, and interacting with other teams was truly inspiring. We will use this result as motivation to achieve even greater success next year.
Related articles
Contact
Aqua Lab, Society for the Study of Robotics, Science Tokyo
Email rogy.aqua@gmail.com