The control of routine fish maneuvers: Connecting midline kinematics to turn outcomes

Howe, Stephen; Astley, Henry C.

doi:10.1002/jez.2398

Cited by 5 publications

(8 citation statements)

References 61 publications

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“…C-starts in live fish exhibit muscle activation patterns that are more akin to the C-start control scheme that we, and others (Jindong and Huosheng 2005, Su et al 2011, have encoded, wherein all the muscles activate simultaneously and deactivate sequentially (Jayne and Lauder 1993). However, in our observations of the kinematics of C-starts, we found that the patterns of developing and propagating curvature were similar regardless of the type of stimulus, though escape maneuvers were much higher intensity than routine maneuvers (Howe and Astley 2020). Interactions between the neuromuscular system, the material properties of the body, muscle physiology, and the forces imposed on the body by the water all likely work together to create the kinematic patterns we observe in live fish (Tytell et al 2011), it would make sense that combinations of similar factors could give rise to the kinematic patterns we observed in the C-start control scheme.…”

Section: Discussionsupporting

confidence: 45%

“…The head was the longest body segment at 30% of the total length. The head in the robot is longer than the head we measured in live fish, but the amount of curvature we measured in this region on the fish's midline was low (figure 1(A), Howe and Astley (2020)). Active segments were the same length at 14% TL.…”

Section: Robot Constructionmentioning

confidence: 62%

“…We found that the performance relationships observed in the robot are generally consistent with those observed in live fish. Total body bending had significant positive effects on both total heading change and maximum centripetal acceleration in both systems (Howe and Astley 2020). Turn duration had a negative effect on acceleration, i.e., shorter turns are faster.…”

Section: Discussionmentioning

confidence: 92%

“…They used artificial intelligence to identify the link lengths and joint centers of a swimming carp and were able to find the oscillation frequency of each joint angle, to be used in their robotic model (Ozmen Koca et al 2018). Behaviors that resemble sequential offset turns are observed in live fish (Webb andFairchild 2001, Howe andAstley 2020). The C-start takes its inspiration from escape maneuvers in live fish wherein steady swimming is interrupted and all the segments bend to one side before returning to their natural position (figures 1(C) and (D)).…”

Section: Introductionmentioning

confidence: 87%

“…We used three different turn mechanisms, two based on previous literature and one based on routine turning behavior we observed in live fish (Howe and Astley 2020). A trial consists of a steady swimming phase (3 tail beats), a coasting phase, the turn, and a final coasting phase.…”

Section: Design Of Turn Mechanismsmentioning

confidence: 99%

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Comparing the turn performance of different motor control schemes in multilink fish-inspired robots

2021

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Fish robots have many possible applications in exploration, industry, research, and continue to increase in design complexity, control, and the behaviors they can complete. Maneuverability is an important metric of fish robot performance, with several strategies being implemented. By far the most common control scheme for fish robot maneuvers is an offset control scheme, wherein the robot’s steady swimming is controlled by sinusoidal function and turns are generated biasing bending to one side or another. An early bio-inspired turn control scheme is based on the C-start escape response observed in live fish. We developed a control scheme that is based on the kinematics of routine maneuvers in live fish that we call the ‘pulse’, which is a pattern of increasing and decreasing curvature that propagates down the body. This pattern of curvature is consistent across a wide range of turn types and can be described with a limited number of variables. We compared the performance of turns using each of these three control schemes across a range of durations and bending amplitudes. We found that C-start and offset turns had the highest heading changes for a given set of inputs, whereas the bio-inspired pulse turns had the highest linear accelerations for a given set of inputs. However, pulses shift the conceptualization of swimming away from it being a continuous behavior towards it being an intermittent behavior that is built by combining individual bending events. Our bio-inspired pulse control scheme has the potential to increase the behavioral flexibility of bio-inspired robotic fish and solve some of the problems associated with integrating different swimming behaviors, despite lower maximal turning performance.

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Section: Discussionsupporting

confidence: 45%

Section: Robot Constructionmentioning

confidence: 62%

Section: Discussionmentioning

confidence: 92%

Section: Introductionmentioning

confidence: 87%

Section: Design Of Turn Mechanismsmentioning

confidence: 99%

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Comparing the turn performance of different motor control schemes in multilink fish-inspired robots

2021

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Testing the effects of body depth on fish maneuverability via robophysical models

Howe¹,

Bryant²,

Duff³

et al. 2021

Bioinspir. Biomim.

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Fish show a wide diversity of body shapes which affect many aspects of their biology, including swimming and feeding performance, and defense from predators. Deep laterally compressed bodies are particularly common, and have evolved multiple times in different families. Functional hypotheses that explain these trends include predator defense and increased maneuverability. While there is strong evidence that increasing body depth helps fish avoid gape-limited predators, the evidence that body shape increases a fish’s maneuverability is ambiguous. We used a two-pronged approach to explore the effects of body shape on the control of maneuvers using both live fish and a robotic model that allowed us to independently vary body shape. We captured ventral video of two tetra species (Gymnocorymbus ternetzi and Aphyocharax anisitsi) performing a wide range of maneuvers to confirm that both species of live fish utilize fundamentally similar body deformations to execute a turn, despite their different body depths. Both species use a propagating ‘pulse’ of midline curvature that is qualitatively similar to prior studies and displayed similar trends in the relationships between body kinematics and performance. We then tested the robotic model’s maneuverability, defined as the total heading change and maximum centripetal acceleration generated during a single pulse, at a range of different input kinematics across three body shapes. We found that deepening bodies increase the robot’s ability to change direction and centripetal acceleration, though centripetal acceleration exhibits diminishing returns beyond a certain body depth. By using a robotic model, we were able to isolate the effects of body shape on maneuverability and clarify this confounded relationship. Studying the functional morphology of complex traits such as body shape and their interaction with complex behavior like maneuverability benefits from both the broad view provided by comprehensive comparative studies, and the control of variables enabled by robophysical experiments.

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Effects of caudal fin stiffness on optimized forward swimming and turning maneuver in a robotic swimmer

Deng,

Li,

Panta

et al. 2024

Bioinspir. Biomim.

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In animal and robot swimmers of Body and Caudal Fin (BCF) form, hydrodynamic thrust is mainly produced by their caudal fins, the stiffness of which has profound effects on both thrust and efficiency of swimming. Caudal fin stiffness also affects the motor control and resulting swimming gaits that correspond to optimal swimming performance; however, their relationship remains scarcely explored. Here using magnetic, modular, undulatory robots (μBots), we tested the effects of caudal fin stiffness on both forward swimming and turning maneuver. We developed six caudal fins with stiffness of more than 3 orders of difference. For a μBot equipped with each caudal fin (and μBot absent of caudal fin), we applied reinforcement learning (RL) in experiments to optimize the motor control for maximizing forward swimming speed or final heading change. The motor control of μBot was generated by a Central Pattern Generator (CPG) for forward swimming or by a series of parameterized square waves for turning maneuver. In forward swimming, the variations in caudal fin stiffness gave rise to three modes of optimized motor frequencies and swimming gaits including no caudal fin (4.6 Hz), stiffness<10-4 Pa·m4 (~10.6 Hz) and stiffness>10-4 Pa·m4 (~8.4 Hz). Swimming speed, however, varied independently with the modes of swimming gaits, and reached maximal at stiffness of 0.23×10-4 Pa·m4, with the μBot without caudal fin achieving the lowest speed. In turning maneuver, caudal fin stiffness had considerable effects on the amplitudes of both initial head steering and subsequent recoil, as well as the final heading change. It had relatively minor effect on the turning motor program except for the μBots without caudal fin. Optimized forward swimming and turning maneuver shared an identical caudal fin stiffness and similar patterns of peduncle and caudal fin motion, suggesting simplicity in the form and function relationship in μBot swimming.

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The control of routine fish maneuvers: Connecting midline kinematics to turn outcomes

Cited by 5 publications

References 61 publications

Comparing the turn performance of different motor control schemes in multilink fish-inspired robots

Comparing the turn performance of different motor control schemes in multilink fish-inspired robots

Testing the effects of body depth on fish maneuverability via robophysical models

Effects of caudal fin stiffness on optimized forward swimming and turning maneuver in a robotic swimmer

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