Vladislav Kopman

Free-Locomotion of Underwater Vehicles Actuated by Ionic Polymer Metal Composites

In this paper, we develop a modeling framework for studying free-locomotion of biomimetic underwater vehicles propelled by vibrating ionic polymer metal composites (IPMCs). The motion of the vehicle body is described using rigid body dynamics in fluid environments. Hydrodynamic effects, such as added mass and damping, are included in the model to enable a thorough description of the vehicles surge, sway, and yaw motions. The time-varying actions exerted by the vibrating IPMC on the vehicle body, including thrust, lift, and moment, are estimated by combining force and vibration measurements with reduced order modeling based on modal analysis. The model predictions are validated through experimental results on a miniature remotely controlled fish-like robotic swimmer.

Design, Modeling, and Characterization of a Miniature Robotic Fish for Research and Education in Biomimetics and Bioinspiration

In this paper, we present the design of a biomimetic robotic fish with a modular caudal fin and analyze its performance. The robots propulsion system is experimentally characterized for different caudal fin geometries by using an ad hoc thrust-measurement system. The static thrust produced by the vibrating tail is expressed in terms of the oscillatory Reynolds number and compared with similar findings in the literature. Nonlinear vibrations of the propulsive tail are modeled using modal analysis and classical results from the study of large vibrations of slender cylinders in fluids. This analysis allows for computing the oscillatory Reynolds number in terms of the input parameters to the tail vibration. Free-swimming experiments are performed to investigate the performance and maneuverability of the robot and correlate static thrust with terminal speed. This robotic platform is currently being used in ethorobotics research for investigating collective behavior of gregarious fish species and in educational fun-science activities for K-12 students.

Closed-loop control of zebrafish response using a bioinspired robotic-fish in a preference test

In this paper, we study the response of zebrafish to a robotic-fish whose morphology and colour pattern are inspired by zebrafish. Experiments are conducted in a three-chambered instrumented water tank where a robotic-fish is juxtaposed with an empty compartment, and the preference of live subjects is scored as the mean time spent in the vicinity of the tanks two lateral sides. The tail-beating of the robotic-fish is controlled in real-time based on feedback from fish motion to explore a spectrum of closed-loop systems, including proportional and integral controllers. Closed-loop control systems are complemented by open-loop strategies, wherein the tail-beat of the robotic-fish is independent of the fish motion. The preference space and the locomotory patterns of fish for each experimental condition are analysed and compared to understand the influence of real-time closed-loop control on zebrafish response. The results of this study show that zebrafish respond differently to the pattern of tail-beating motion executed by the robotic-fish. Specifically, the preference and behaviour of zebrafish depend on whether the robotic-fish tail-beating frequency is controlled as a function of fish motion and how such closed-loop control is implemented.

Zebrafish response to robotic fish: preference experiments on isolated individuals and small shoals

Recently developed bioinspired robots imitate their live counterparts in both aspect and functionality. Nevertheless, whether these devices can be integrated within the ecological niche inspiring their design is seldom tested experimentally. An elemental research question concerns the feasibility of modulating spontaneous behaviour of animal systems through bioinspired robotics. The following study explores the possibility of engineering a robotic fish capable of influencing the behaviour of live zebrafish (Danio rerio) in a dichotomous preference test. While we observe that the preference for the robotic fish never exceeds the preference for a conspecific, our data show that the robot is successful in attracting both isolated individuals and small shoals and that such capability is influenced by its bioinspired features. In particular, we find that the robots undulations enhance its degree of attractiveness, despite the noise inherent in the actuation system. This is the first experimental evidence that live zebrafish behaviour can be influenced by engineered robots. Such robotic platforms may constitute a valuable tool to investigate the bases of social behaviour and uncover the fundamental determinants of animal functions and dysfunctions.

Dynamic Modeling of a Robotic Fish Propelled by a Compliant Tail

In this paper, a dynamic model for a robotic fish propelled by a tail with a flexible fin is presented. The robotic fish is composed of two links connected by an actuated joint; the frontal link is rigid and acts as the robotic fish body, while the rear link serves as the tail. The latter comprises a rigid element connected to a flexible caudal fin, whose underwater vibration is responsible for propulsion. The dynamics of the frontal link are described using Kirchhoffs equations of motion for rigid bodies in quiescent fluids. The tail vibration is modeled using Euler-Bernoulli beam theory and the effect of the encompassing fluid is described using the Morison equation. The thrust production is assessed from static thrust data in terms of the fin-tip displacement; other salient model parameters are estimated through a nonlinear least squares technique. The model is validated against experimental data on circular and S-shaped trajectories. The model can be used for simulation, prediction, design optimization, and control, as it allows for the description of the robots motion as a function of the unique input of the system, that is, the servomotor angle. Within the latter application, a heading control algorithm, in which the controller is tuned on the basis of the dynamic model, is presented.

MASUV-1: A Miniature Underwater Vehicle With Multidirectional Thrust Vectoring for Safe Animal Interactions

In this paper, we present the design and proof of concept of a streamlined, low-cost, and smooth-hulled underwater vehicle, miniature animal safe underwater vehicle (MASUV-1), utilizing an entirely enclosed propulsion and steering system. This allows for safely operating MASUV-1 in the vicinity of marine mammals, and thus, facilitates animal behavior research as well as coping with traditional engineering and scientific missions in marine mammal populated environments. The vehicle utilizes an ad hoc designed multidirectional thrust-vectoring system for steering, based on multiple servo motors and pushrods. Tests of the vehicle in a stillwater environment show high maneuverability at speeds comparable with similar torpedo-type class underwater vehicles.

A miniature and low-cost robotic fish for ethorobotics research and engineering education I: Bioinspired design

The development of underwater biomimetic robots has recently become an active research topic due to their stealth, performance, and maneuverability. In this two-part paper, we present the system design and characterization of a multipurpose, miniature, bioinspired low-cost robotic fish implemented in a fun-science activity for pre-high school students at the New York Aquarium; the activity is aimed at igniting K-12 students’ interest in science, technology, engineering, and mathematics (STEM) and to attract them toward engineering careers. The robot features a servomotor-actuated modular caudal fin for selection of swimming modality and thrust optimization. The thrust produced by various caudal fin geometries is experimentally quantified, reported, and discussed. In addition to its applications in K-12 education, this robotics platform is utilized for several robot-live fish interaction studies, where the effect of robot leadership in fish shoals is investigated.Copyright

Control-oriented modeling of Ionic Polymer Metal Composites for biomimetic underwater propulsion

In this paper, we develop a control-oriented model for underwater vehicles propelled by vibrating Ionic Polymer Metal Composites (IPMCs). The time-varying actions exerted by the IPMC on the vehicle body, including thrust, lift, and moment, are estimated by combining force and vibration measurements with reduced order modeling based on modal analysis. The model predictions are validated through experimental results on a miniature remotely-controlled biomimetic underwater vehicle. The proposed model finds application in designing autonomous missions for such vehicles, including controlled interactions with live fish for the purpose of elucidating leadership mechanisms in gregarious fish shoals.

Using a Bioinspired Robotic-Fish for Closed-Loop Control of Zebrafish Response in a Preference Test

This paper studies the response of zebrafish to a bioinspired robotic-fish. The robot’s color pattern and morphophysiology are modulated to emphasize features normally admired by zebrafish in conspecifics. A three-chambered instrumented tank is utilized to conduct a series of preference tests, offering the robotic-fish as a stimulus, juxtaposed with an empty compartment, to live zebrafish. The time spent by fish in the proximity of either stimulus compartment is used to score the preference of an individual to a stimulus. The tail-beating motion of the robotic fish is manipulated based on closed- and open-loop control strategies. The closed-loop controller uses the distance of the live-fish from the robotic-stimulus as its control input, while the open-loop controller provides a tail-beating motion, irrespective of fish behavior. Live-fish locomotion patterns and their preference space are compared and analyzed to ascertain the effects of closed-loop control on zebrafish response. This study’s results suggest that closed-loop control reinforces attraction to the robotic-stimulus, as compared to the open-loop approach, over extended exposure to the robot, therefore aiding against habituation to a stimulus.Copyright

Dynamic Modeling of a Compliant Tail-Propelled Robotic Fish

This paper presents a dynamic model for a class of robotic fish propelled by a tail with a flexible fin. The robot is comprised of a rigid frontal link acting as a body and a rear link serving as the tail. The tail includes a rigid component, hinged to the body through a servomotor, which is connected to a compliant caudal fin whose underwater vibration induces the propulsion. The robot’s body dynamics is modeled using Kirchhoff’s equations of motion of bodies in quiescent fluids, while its tail motion is described with Euler-Bernoulli beam theory, accounting for the effect of the encompassing fluid through the Morison equation. Simulation data of the model is compared with experimental data. Applications of the model include simulation, prediction, design optimization, and control.Copyright