NC State Develops Feather Star-Inspired Underwater Robot
Researchers at North Carolina State University have developed a soft underwater robot capable of three dimensional movement. This new device, drawing inspiration from feather stars, uses only two actuators to achieve a range of motion typically requiring six. The design enables movement forward, backward, upward, downward, and rotation around its central axis, significantly reducing mechanical complexity for such maneuverability.
The robot's design incorporates what the researchers term "mechanical intelligence." This principle dictates that a robot's physical structure and its inherent interactions with its surrounding environment largely determine its behaviour, thereby reducing the need for extensive control input from computing systems or human operators. Conventional robotic systems performing similar three dimensional manoeuvres would ordinarily demand a minimum of six actuators to achieve comparable movement.
The structure of the robot features four elastic wings arranged around a central disk. These wings are categorised as monostable, meaning they bend under the application of force from an actuator but naturally revert to their original, unbent position once that force is removed. So, this particular mechanical arrangement facilitates the generation of various motion types without the requirement for a dedicated actuator for each individual direction or movement.
The robot's two actuators are housed within its central disk, exerting control over all four wings. When both actuators are simultaneously activated, the wings rapidly snap downwards. Conversely, when the actuators are switched off, the elastic wings promptly return to an upward position. Repeating this activation and deactivation cycle quickly causes the robot to flap its wings, propelling itself upwards through the water.
Modulating the speed of this flapping action allows the robot to maintain a stationary position or hover. The researchers refer to this specific behaviour as "jellyfish mode," illustrating its slow, deliberate movements. But, the same underlying hardware can also generate horizontal motion through an altered control strategy for the actuators, showcasing the versatility of the core design.
Activating only a single actuator causes one wing to flutter. This action functions akin to a tailfin, enabling the robot to push itself either forward or backward through the aquatic environment. This distinct operational state is designated by the researchers as "fish mode," highlighting its linear directional propulsion capability. The robot can also execute rotation around its central axis.
By rapidly alternating the activation between the two actuators, the research team generates asymmetric wing movements. These unbalanced forces induce a spinning motion in the robot. This designated "rotor mode" provides critical directional control, allowing the soft robotic device to steer effectively while submerged underwater. And, the combined capabilities of these three movement modes provide the soft robot with comprehensive command over its vertical, horizontal, and rotational motions.
The research team has demonstrated the system's operational abilities, including exploring underwater environments equipped with a camera and lifting objects. These tasks were performed either by a single robot or through the coordinated actions of multiple units. According to Jie Yin, a professor of mechanical and aerospace engineering at NCSU and corresponding author of the study, the work illustrates the potential for creating robotic devices with an extensive range of motion using a minimal number of actuators, achieved through intelligent design techniques.
This particular design represents an evolution from earlier work conducted by the same team, which involved a manta ray inspired aquatic robot. That previous iteration could move rapidly through water but did not possess the comparable three dimensional manoeuvrability of the current feather star model. Instead of incorporating additional motors or more intricate mechanical mechanisms, the researchers instead focused on achieving expanded movement capabilities directly via the robot's physical structure.
The compact nature of this design offers a suitable platform for various underwater robotic applications. Specifically, it addresses scenarios where high manoeuvrability and mechanical simplicity are considered important factors. Future work is slated to concentrate on the development of a fully wireless version of the robot. Furthermore, the team plans to explore potential applications through collaborative efforts with researchers from diverse scientific fields.
North Carolina State University researchers developed a feather star inspired underwater robot.
The robot achieves three dimensional movement using only two actuators, fewer than typically required.
Its design incorporates "mechanical intelligence," relying on physical structure for diverse motions.
Three distinct movement modes, including "jellyfish mode," "fish mode," and "rotor mode," control vertical, horizontal, and rotational actions.
The compact design is suitable for underwater robotic applications requiring manoeuvrability and mechanical simplicity. Source: interestingengineering
