Autonomous Soft Robotic Fish Capable of Escape Maneuvers Using Fluidic Elastomer Actuators

Abstract

In this work we describe an autonomous soft-bodied robot that is both self-contained and capable of rapid, continuum-body motion. We detail the design, modeling, fabrication, and control of the soft fish, focusing on enabling the robot to perform rapid escape responses. The robot employs a compliant body with embedded actuators emulating the slender anatomical form of a fish. In addition, the robot has a novel fluidic actuation system that drives body motion and has all the subsystems of a traditional robot onboard: power, actuation, processing, and control. At the core of the fish's soft body is an array of fluidic elastomer actuators. We design the fish to emulate escape responses in addition to forward swimming because such maneuvers require rapid body accelerations and continuum-body motion. These maneuvers showcase the performance capabilities of this self-contained robot. The kinematics and controllability of the robot during simulated escape response maneuvers are analyzed and compared with studies on biological fish. We show that during escape responses, the soft-bodied robot has similar input-output relationships to those observed in biological fish. The major implication of this work is that we show soft robots can be both self-contained and capable of rapid body motion.

Untethered soft robotics

“…Many other untethered soft robots take advantage of marine environments to circumvent static friction and offload the mass of their auxiliary components 57,62,119,120 , thereby improving the system efficiency 121 . These principles allowed the autonomous soft robotic fish developed by Marchese et al to benefit from its large size and incorporate hydraulic actuators and power within its body cavity 119,120 (Fig.…”

“…These principles allowed the autonomous soft robotic fish developed by Marchese et al to benefit from its large size and incorporate hydraulic actuators and power within its body cavity 119,120 (Fig. 6c).…”

Fundamentals of soft robot locomotion

“…Flexible swimming appendages can be exploited to harvest energy by continuously storing and releasing energy in the elastic oars and inducing changes in the surface area of the oars to increase thrust in the power stroke and reduce drag in the recovery stroke [110,114]. Finally, an elastic deformable body allows the storage and sudden release of energy, enabling fast starting that resembles the escape manoeuvres of some fish [112,113].…”

Automatic design of fiber-reinforced soft actuators for trajectory matching

“…For example, this robot could be a robot arm that moves along a certain path or a wearable robot that assists with motion of a limb. For conventional hard robots, methods have been developed to describe the forward kinematics (i.e., for given actuator inputs, what will the configuration of the robot be) and inverse kinematics (i.e., for a desired configuration of the robot, what should the actuator inputs be) (1-4).Recently, there has been significant progress in the field of soft robotics, with the development of many soft grippers (5, 6), locomotion robots (7,8), and assistive devices (9). Although their inherent compliance, easy fabrication, and ability to achieve complex output motions from simple inputs have made soft robots very popular (10, 11), there is growing recognition that the development of methods for efficiently designing actuators for particular functions is essential to the advancement of the field.…”