A bio-inspired robotic fish utilizes the snap-through buckling of its spine to generate accelerations of more than 20g

Abstract

Inspired by the fastest observed live fishes, we have designed, built and tested a robotic fish that emulates the fast-start maneuver of these fishes and generates acceleration and velocity magnitudes comparable to those of the live fishes within the same time scale. We have designed the robotic fish such that it uses the snap-through bucking of its spine to generate the fast-start response. We have used a dynamic snap-through buckling model and a series of experiments on a beam under snap-through buckling to describe the robotic fish's motion. Our under-actuated robot relies on passive dynamics of a continuous beam to generate organic waveforms. In its transient fast-start maneuver, our robotic fish produces mode shapes very similar to those observed in live fishes, by going through a snap-through bifurcation. We have also used a nonlinear structural model subjected to a non-conservative eccentric compressive force, which is constrained to act tangential to the structure at all times, coupled with a simple fluid dynamic model to approximate the transient behavior of the robot. We relate the numerical results from our nonlinear model to the dynamics observed in the live system proposing an updated kinematic model to understand the mode shapes observed in the fast-start maneuver of the live fishes. We also report on deploying the robotic fish in a river.

Research Development on Fish Swimming

“…Fishes first bend their body to C-shape and then recoil their body quickly to accelerate. Gazzola identified the C-start pattern which minimize the escape distance and Currier designed a robotic fish that can generates fast-start accelerations of more than 20g by utilizing a dynamic snap-through buckling mechanism [85,113]. As for turning locomotion, a fundamental life function, fish can use it to change swimming direction frequently and flexibly for finding food or mates.…”

Role of Electromechanical Coupling, Locomotion Type and Damping on the Effectiveness of Fish-Like Robot Energy Harvesters

“…These animals engage their musculature and translate a moving wave along the body to the tail tip to produce thrust for swimming. BCF locomotion can be represented as a sinusoidal waveform which is restricted by a polynomial envelope, as shown in Equation (1). The respective constraints of this motion are dependent on the animal to be replicated [15].…”

“…Aquatic unmanned vehicles (AUVs) are being developed and advancing into bioinspired body undulating-oscillatory locomotion, replicating fishes [1,2]. Typical aquatic systems are rigid-bodied, controlled with propellers and often tethered [3].…”

A fluid-driven soft robotic fish inspired by fish muscle architecture

“…However, the swimming ability and environmental adaptability were limited because the system relied on the front-facing oscillator to generate backward fish waves instead of a distributed drive system. Currier et al [11] reported a dependent bio-inspired fish with airbags wrapped around a central elastic layer. The fish could be bent by applying pressure to one side, and the mechanism of the rapid C-shaped start of the fish was elucidated.…”