A research group from the University of Electro-Communications Graduate School, Meijo University, and Tokyo University of Science has developed a direct-drive fish robot as a new driving method for biomimetic underwater robots, achieving speeds equal to or greater than those of real fish.
Conventional biomimetic underwater robots can be broadly divided into those that use electromagnetic motors or soft artificial muscles as a power source. Electromagnetic motors have excellent output and responsiveness, but robots based on them use a large number of additional parts such as gears, which raises concerns about the complexity of the structure, increased weight, and reduced durability against impacts. On the other hand, robots using soft artificial muscles have a simple structure and are flexible like living organisms, but have problems with low output and responsiveness.
The research group believed that high swimming performance could be achieved by directly driving a simple and flexible structure with an electromagnetic motor, and therefore designed, manufactured, and analyzed a fish robot that uses a direct drive method as a new drive method for biomimetic underwater robots.
As a result, the fish robot was able to swim at a maximum speed of 2.6m/s. This corresponds to a speed-to-body-length ratio of 6.3 body lengths/second, which is the speed divided by the body length. Based on existing biological data, this performance is equal to or better than that of real fish. In addition, the direct drive system allows for a wide rotation angle of the electromagnetic motor, allowing the body to deform rapidly and greatly. This allows the robot to achieve the fastest turning speed (1450º/s in-place turning) of any currently available underwater robot.
The above results demonstrate that the direct drive method is an effective new technology for improving the performance of biomimetic underwater robots. It is expected that the application of these results will lead to the realization of high-performance underwater robots with a variety of configurations that can be used in a variety of situations.
Paper information:[npj Robotics] Agile robotic fish based on direct drive of continuum body