Paul Phamduy

Fish and robots swimming together in a water tunnel: robot color and tail-beat frequency influence fish behavior.

The possibility of integrating bioinspired robots in groups of live social animals may constitute a valuable tool to study the basis of social behavior and uncover the fundamental determinants of animal functions and dysfunctions. In this study, we investigate the interactions between individual golden shiners (Notemigonus crysoleucas) and robotic fish swimming together in a water tunnel at constant flow velocity. The robotic fish is designed to mimic its live counterpart in the aspect ratio, body shape, dimension, and locomotory pattern. Fish positional preference with respect to the robot is experimentally analyzed as the robots color pattern and tail-beat frequency are varied. Behavioral observations are corroborated by particle image velocimetry studies aimed at investigating the flow structure behind the robotic fish. Experimental results show that the time spent by golden shiners in the vicinity of the bioinspired robotic fish is the highest when the robot mimics their natural color pattern and beats its tail at the same frequency. In these conditions, fish tend to swim at the same depth of the robotic fish, where the wake from the robotic fish is stronger and hydrodynamic return is most likely to be effective.

Fish and robot dancing together: bluefin killifish females respond differently to the courtship of a robot with varying color morphs

The experimental integration of bioinspired robots in groups of social animals has become a valuable tool to understand the basis of social behavior and uncover the fundamental determinants of animal communication. In this study, we measured the preference of fertile female bluefin killifish (Lucania goodei) for robotic replicas whose aspect ratio, body size, motion pattern, and color morph were inspired by adult male killifish. The motion of the fish replica was controlled via a robotic platform, which simulated the typical courtship behavior observed in killifish males. The positional preferences of females were measured for three different color morphs (red, yellow, and blue). While variation in preference was high among females, females tend to spend more time in the vicinity of the yellow painted robot replicas. This preference may have emerged because the yellow robot replicas were very bright, particularly in the longer wavelengths (550–700 nm) compared to the red and blue replicas. These findings are in agreement with previous observations in mosquitofish and zebrafish on fish preference for artificially enhanced yellow pigmentation.

Large-Scale Particle Image Velocimetry From an Unmanned Aerial Vehicle

Large-scale particle image velocimetry (LSPIV) enables nonintrusive and continuous characterization of surface flow velocities in natural watersheds. However, current LSPIV implementations are based on hxed cameras that only allow for surface flow monitoring at a limited number of locations on the water stream. This paper seeks to leverage the growing held of unmanned aerial vehicles to transform LSPIV practice, by enabling rapid characterization of large water flow systems in areas that may be difhcult to access by human operators. Toward this aim, a lightweight and low cost quadrotor is developed to host a digital acquisition system for LSPIV. A gimbal is realized in house to maintain the camera lens orthogonal with respect to the water surface, thus preventing image orthorectihcation. Field experiments demonstrate that the vehicle is able to stably hover above an area of 1 × 1 m2 for 4 min with a payload of 532 g. The feasibility of quadrotor-based LSPIV is demonstrated through tests in an outdoor laboratory setting and over a natural stream.

Influence of robotic shoal size, configuration, and activity on zebrafish behavior in a free-swimming environment.

In animal studies, robots have been recently used as a valid tool for testing a wide spectrum of hypotheses. These robots often exploit visual or auditory cues to modulate animal behavior. The propensity of zebrafish, a model organism in biological studies, toward fish with similar color patterns and shape has been leveraged to design biologically inspired robots that successfully attract zebrafish in preference tests. With an aim of extending the application of such robots to field studies, here, we investigate the response of zebrafish to multiple robotic fish swimming at different speeds and in varying arrangements. A soft real-time multi-target tracking and control system remotely steers the robots in circular trajectories during the experimental trials. Our findings indicate a complex behavioral response of zebrafish to biologically inspired robots. More robots produce a significant change in salient measures of stress, with a fast robot swimming alone causing more freezing and erratic activity than two robots swimming slowly together. In addition, fish spend more time in the proximity of a robot when they swim far apart than when the robots swim close to each other. Increase in the number of robots also significantly alters the degree of alignment of fish motion with a robot. Results from this study are expected to advance our understanding of robot perception by live animals and aid in hypothesis-driven studies in unconstrained free-swimming environments.

Swimming Robots Have Scaling Laws, Too

Aquatic animals of vastly different size show a simple relationship between swimming speed and body kinematics. Swimming robots, whose morphology and gaits are inspired by those animals, are not an exception.

An Autonomous Charging System for a Robotic Fish

The use of autonomous underwater vehicles is often hampered by stringent power constraints that limit the duration of their deployment. Here, we present a novel autonomous underwater charging system for robotic fish. The system features a charging station designed with form-fit claws to facilitate the robotic fish docking. A controller is implemented externally to monitor the battery level of the robotic fish, swimming autonomously in two dimensions. When the battery level is low, the controller commands the robotic fish to approach the charging station using video feedback from an overhead camera. The approach angle of the robotic fish to the charging station is optimized through a series of experiments, assessing the success of both docking and electrical contact, as well as the time to approach the charging station. To demonstrate the feasibility of the autonomous charging system, the robotic fish is monitored as it cycles through periods of charging and discharging while swimming in the tank. The proposed system is expected to find application in laboratory and educational settings, where robotic fish should operate with minimal supervision and assistance from technical staff over extended time periods.

Design and characterization of a miniature free-swimming robotic fish based on multi-material 3D printing

Research in animal behavior is increasingly benefiting from the field of robotics, whereby robots are being continuously integrated in a number of hypothesis-driven studies. A variety of robotic fish have been designed after the morphophysiology of live fish to study social behavior. Of the current design factors limiting the mimicry of live fish, size is a critical drawback, with available robotic fish generally exceeding the size of popular fish species for laboratory experiments. Here, we present the design and testing of a novel free-swimming miniature robotic fish for animal-robot studies. The robotic fish capitalizes on recent advances in multi-material three-dimensional printing that afford the integration of a range of material properties in a single print task. This capability has been leveraged in a novel design of a robotic fish, where waterproofing and kinematic functionalities are incorporated in the robotic fish. Particle image velocimetry is leveraged to systematically examine thrust production, and independent experiments are conducted in a water tunnel to evaluate drag. This information is utilized to aid the study of the forward locomotion of the robotic fish, through reduced-order modeling and experiments. Swimming efficiency and turning maneuverability is demonstrated through target experiments. This robotic fish prototype is envisaged as a tool for animal-robot interaction studies, overcoming size limitations of current design.

Closed-loop control of zebrafish behaviour in three dimensions using a robotic stimulus

Robotics is continuously being integrated in animal behaviour studies to create customizable, controllable, and repeatable stimuli. However, few systems have capitalized on recent breakthroughs in computer vision and real-time control to enable a two-way interaction between the animal and the robot. Here, we present a “closed-loop control” system to investigate the behaviour of zebrafish, a popular animal model in preclinical studies. The system allows for actuating a biologically-inspired 3D-printed replica in a 3D workspace, in response to the behaviour of a zebrafish. We demonstrate the role of closed-loop control in modulating the response of zebrafish, across a range of behavioural and information-theoretic measures. Our results suggest that closed-loop control could enhance the degree of biomimicry of the replica, by increasing the attraction of live subjects and their interaction with the stimulus. Interactive experiments hold promise to advance our understanding of zebrafish, offering new means for high throughput behavioural phenotyping.

Fish-robot interactions in a free-swimming environment: Effects of speed and configuration of robots on live fish

We explore fish-robot interactions in a comprehensive set of experiments designed to highlight the effects of speed and configuration of bioinspired robots on live zebrafish. The robot design and movement is inspired by salient features of attraction in zebrafish and includes enhanced coloration, aspect ratio of a fertile female, and carangiform/subcarangiformlocomotion. The robots are autonomously controlled to swim in circular trajectories in the presence of live fish. Our results indicate that robot configuration significantly affects both the fish distance to the robots and the time spent near them.

Characterization of Micromachined Seesaw Type Microphone

A seesaw type microphone is characterized to study its feasibility for sound source localization. The microphone is composed of a flexible rectangular diaphragm sustained by two torsion-bars. With this structure, the microphone has two main dynamic modes: rocking mode from the twisting of the torsion bars and bending mode from the bending of the flexible diaphragm. Thus, the microphone’s motion is a combination of the two modes. Depending on the frequency of the incident sound and its arrival time difference at each side of the seesaw type microphone, relative motion of both sides of the seesaw type microphone is changed. By measuring relative amplitude and phase of the motion at each side of the microphone, arrival time difference of the sound source at each side can be estimated, and then, localization of the sound source is feasible. In this paper, we present that the microphone shows a significant vibration difference from each side when AC with 45° phase difference is applied to each side of the microphone to mimic the microphone receiving angled incoming sound.Copyright