A Design Concept and Kinematic Model for a Soft Aquatic Robot with Complex Bio-mimicking Motion

Shokoofeh Abbaszadeh,Stefan Hoerner,Roberto Leidhold

doi:10.1007/s42235-021-00126-4

Shokoofeh Abbaszadeh, Stefan Hoerner + Show 1 more

Open Access

https://doi.org/10.1007/s42235-021-00126-4

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Abstract

Fish mortality assessments for turbine passages are currently performed by live-animal testing with up to a hundred thousand fish per year in Germany. A propelled sensor device could act as a fish surrogate. In this context, the study presented here investigates the state of the art via a thorough literature review on propulsion systems for aquatic robots. An evaluation of propulsion performance, weight, size and complexity of the motion achievable allows for the selection of an optimal concept for such a fish mimicking device carrying the sensors. In the second step, the design of a bioinspired soft robotic fish driven by an unconventional drive system is described. It is based on piezoceramic actuators, which allow for motion with five degrees of freedom (DOF) and the creation of complex bio-mimicking body motions. A kinematic model for the motion’s characteristics is developed, to achieve accurate position feedback with the use of strain gauges. Optical measurements validate the complex deformation of the body and deliver the basis for the calibration of the kinematic model. Finally, it can be shown, that the calibrated model presented allows the tracking of the deformation of the entire body with an accuracy of 0.1 mm.

Highlights

According to the European Water Framework Directive, a risk assessment for fish injury and mortality in turbine passages is mandatory for innovative technologies, new installations, and existing hydropower facilities
As a consequence of the findings reported in these various studies, it was considered that a macro-fiber composites (MFC) and dielectric elastomer actuators (DEA) based propulsion system would best fit the requirements stated above and the MFC was chosen to perform some experiments
A thorough literature review was performed for both conventional and unconventional propulsion systems used for bio-mimicking, aquatic robots

Summary

Introduction

According to the European Water Framework Directive, a risk assessment for fish injury and mortality in turbine passages is mandatory for innovative technologies, new installations, and existing hydropower facilities. State-ofthe-art methodologies to determine the risk of injury to fish in downstream turbine passages deploy live-animal tests, injecting wild fish of different species in the turbine. These live tests lead to serious injuries or even the death of the probands in many cases, as shown by Pracheil et al [1], but are very time and cost intensive. The robot will have to meet the required biological similarity to the real probands and survive the harsh conditions during a turbine passage This leads to very specific and particular requirements, which are subsequently defined in Sect.

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Conclusion