Dynamic Modeling of a Compliant Tail-Propelled Robotic Fish

2013 ◽  
Author(s):  
Vladislav Kopman ◽  
Jeffrey Laut ◽  
Maurizio Porfiri ◽  
Francesco Acquaviva ◽  
Alessandro Rizzo
Keyword(s):  
Equations Of Motion ◽  
Beam Theory ◽  
The Body ◽  
Robotic Fish ◽  
Body Dynamics ◽  
Flexible Fin ◽  
Optimization And Control ◽  
Rigid Component ◽  
And Control ◽  
Euler Bernoulli Beam

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.

Dynamic Modeling of Robotic Fish With a Base-Actuated Flexible Tail

2014 ◽  
Vol 137 (1) ◽  
Author(s):  
Jianxun Wang ◽  
Philip K. McKinley ◽  
Xiaobo Tan
Keyword(s):  
Hydrodynamic Force ◽  
Beam Theory ◽  
Small Deformation ◽  
Robotic Fish ◽  
Free Swimming ◽  
Flexible Tail ◽  
In Series ◽  
Optimization And Control ◽  
And Control ◽  
Body Theory

In this paper, we develop a new dynamic model for a robotic fish propelled by a flexible tail actuated at the base. The tail is modeled by multiple rigid segments connected in series through rotational springs and dampers, and the hydrodynamic force on each segment is evaluated using Lighthill's large-amplitude elongated-body theory. For comparison, we also construct a model using linear beam theory to capture the beam dynamics. To assess the accuracy of the models, we conducted experiments with a free-swimming robotic fish. The results show that the two models have almost identical predictions when the tail undergoes small deformation, but only the proposed multisegment model matches the experimental measurement closely for all tail motions, demonstrating its promise in the optimization and control of tail-actuated robotic fish.

scholarly journals Design and Control of an Embedded Vision Guided Robotic Fish with Multiple Control Surfaces

2014 ◽  
Vol 2014 ◽  
pp. 1-13 ◽  
Author(s):  
Junzhi Yu ◽  
Kai Wang ◽  
Min Tan ◽  
Jianwei Zhang
Keyword(s):  
Visual Processing ◽  
Vision System ◽  
The Body ◽  
Robotic Fish ◽  
Multiple Control ◽  
Caudal Fin ◽  
Embedded Vision ◽  
And Control ◽  
Control Surfaces ◽  
Pelvic Fin

This paper focuses on the development and control issues of a self-propelled robotic fish with multiple artificial control surfaces and an embedded vision system. By virtue of the hybrid propulsion capability in the body plus the caudal fin and the complementary maneuverability in accessory fins, a synthesized propulsion scheme including a caudal fin, a pair of pectoral fins, and a pelvic fin is proposed. To achieve flexible yet stable motions in aquatic environments, a central pattern generator- (CPG-) based control method is employed. Meanwhile, a monocular underwater vision serves as sensory feedback that modifies the control parameters. The integration of the CPG-based motion control and the visual processing in an embedded microcontroller allows the robotic fish to navigate online. Aquatic tests demonstrate the efficacy of the proposed mechatronic design and swimming control methods. Particularly, a pelvic fin actuated sideward swimming gait was first implemented. It is also found that the speeds and maneuverability of the robotic fish with coordinated control surfaces were largely superior to that of the swimming robot propelled by a single control surface.

Anguilliform body dynamics: modelling the interaction between muscle activation and body curvature

1991 ◽  
Vol 334 (1271) ◽  
pp. 385-390 ◽  
Keyword(s):  
Muscle Activation ◽  
Equations Of Motion ◽  
Relative Displacement ◽  
Travelling Wave ◽  
The Body ◽  
Linear Functions ◽  
Careful Examination ◽  
Body Tissues ◽  
Body Dynamics ◽  
Dynamics Modelling

A simple two-dimensional rod and pivot model is proposed for the mechanical structure of the lamprey, each pivot being controlled by a muscle segment attached via perpendicular extensions to the two rods. The elastic and viscous properties of the body tissues (including muscle) are described as linear functions of the relative displacement and angular velocity of the rods at each pivot. The contractile properties of the muscle are introduced as time-dependent forcing torques at the pivots, which are generated by a travelling wave of activation. The angles between the rods at each pivot are used as adapted coordinates, and the equations of motion are linearized by assuming low curvature dynamics, corresponding to slow swimming speeds. Investigation of these equations with varying viscous and elastic parameters leads to a reconstruction of a lamprey viewed in motion on a smooth flat surface out of water. The most striking feature is of an apparently standing wave motion, which is indeed observed in the real animal but which on careful examination in the model corresponds to a travelling wave of varying amplitude.

Evolution of Rotations of a Rigid Body Under the Action of Restoring and Control Moments

2005 ◽  
Author(s):  
L. D. Akulenko ◽  
D. D. Leshchenko ◽  
T. A. Kozachenko
Keyword(s):  
Rigid Body ◽  
Equations Of Motion ◽  
The Body ◽  
System Of Equations ◽  
Slow Time ◽  
Case Examples ◽  
First Approximation ◽  
Nutation Angle ◽  
Regular Precession ◽  
And Control

Perturbed rotations of a rigid body close to the regular precession in the Lagrangian case under the action of a restoring moment depending on slow time and nutation angle, as well as a perturbing moment slowly varying with time, are studied. The body is assumed to spin rapidly, and the restoring and perturbing moments are assumed to be small with a certain hierarchy of smallness of the components. A first approximation averaged system of equations of motion for an essentially nonlinear two-frequency system is obtained in the nonresonance case. Examples of motion of a body under the action of particular restoring, perturbing, and control moments of force are considered.

Dynamic Behavior of Vehicles Travelling on Bridges

1993 ◽  
Author(s):  
Ebrahim Esmailzadeh ◽  
Mehrdaad Ghorashi
Keyword(s):  
Boundary Conditions ◽  
Dynamic Behavior ◽  
Numerical Solutions ◽  
Equations Of Motion ◽  
Beam Theory ◽  
Parameter System ◽  
Moving Vehicle ◽  
Lumped Parameter ◽  
Euler Bernoulli Beam ◽  
Two Degree Of Freedom

Abstract An investigation into the dynamic behavior of a bridge with simply supported boundary conditions, carrying a moving vehicle, is performed. The vehicle has been modelled as a two degree of freedom lumped-parameter system travelling at a uniform speed. Furthermore, the bridge is assumed to obey the Euler-Bernoulli beam theory of vibration. This analysis may well be applied to a beam with different boundary conditions, but the computer simulation results given in this paper are set for only the case of freely hinged ends. Numerical solutions for the derived differential equations of motion are obtained and their close agreement, in some extreme cases, with those reported earlier by the authors are observed. Finally, the effect of speed on the maximum dynamic deflection of bridge is shown to be of much importance and hence an estimation for the critical speed of the vehicle is presented.

Flight mechanics of a free-wing tilt-body aircraft

2008 ◽  
Vol 112 (1137) ◽  
pp. 625-640
Author(s):  
K. Ro ◽  
J. W. Kamman ◽  
J. B. Barlow
Keyword(s):  
Mathematical Model ◽  
Incidence Angle ◽  
Equations Of Motion ◽  
Dynamic Modelling ◽  
Flight Simulation ◽  
The Body ◽  
Flight Mechanics ◽  
Short Takeoff And Landing ◽  
And Control ◽  
The Mathematical Model

Abstract The free-wing tilt-body aircraft refers to a vehicle configuration in which the wing, fuselage, and empennage are in a longitudinally articulated connection. This allows the main wing to freely rotate relative to the body, while the empennage, which is in the form of a long twin boom connected to the rear of the body, changes its incidence angle relative to the body in response to external commands. The principal advantages claimed for the configuration are short takeoff and landing capability, and reduced gust sensitivity. The aerodynamics of the free-wing tilt-body configuration has been previously studied, but analysis of its flight mechanics is limited. In this paper we present derivations of the flight dynamic equations of motion using multi-body dynamic modelling techniques, and combine the resulting equations of motion with experimental aerodynamic data to achieve a nonlinear mathematical model for flight simulation of a generic free-wing tilt-body vehicle. The mathematical model is suitable for the study of detailed dynamic characteristics as well as for model based control law synthesis. Key flight performance, and stability and control characteristics of a generic configuration are obtained from the mathematical model.

Dynamic Analysis of a Beam-Type Resonator With Off-Axis Attached Mass

2012 ◽  
Author(s):  
Pezhman A. Hassanpour ◽  
Kamran Behdinan
Keyword(s):  
Equations Of Motion ◽  
Center Of Mass ◽  
Beam Theory ◽  
Numerical Approach ◽  
Governing Equations ◽  
Bernoulli Beam ◽  
Comb Drive ◽  
Comb Drives ◽  
Beam Type ◽  
Euler Bernoulli Beam

In this paper, the model of a micro-machined beam-type resonator is presented. The resonator is a micro-bridge which is modeled using Euler-Bernoulli beam theory. A comb-drive electrostatic actuator is attached to the micro-bridge for the excitation/detection of vibrations. In the models presented in the literature, it is assumed that the center of mass of the comb-drive is located on the neutral axis of the beam. In this paper, it is demonstrated that this assumption can not be applied for asymmetric-shaped comb-drives. Furthermore, the governing equations of motion are derived by relaxing the above assumption. It has been shown that the off-axis center of mass of the comb-drive generates an amplitude-dependent transverse force in the beam, which is essentially a nonlinear effect. The governing equations of motion are solved using a hybrid analytical-numerical approach. The end application of the structure under investigation is in resonant sensing and energy harvesting applications.

Nonlinear Free Vibration of a Beam With Off-Axis Attached Mass

2013 ◽  
Author(s):  
Pezhman A. Hassanpour
Keyword(s):  
Free Vibration ◽  
Multiple Scales ◽  
Equations Of Motion ◽  
Center Of Mass ◽  
Beam Theory ◽  
Governing Equations ◽  
Attached Mass ◽  
Lumped Mass ◽  
Nonlinear Free Vibration ◽  
Euler Bernoulli Beam

A model of a clamped-clamped beam with an attached lumped mass is presented in this paper. The system is modeled using the Euler-Bernoulli beam theory. In the models presented in literature, it is assumed that the center of mass of the attached mass is located on the neutral axis of the beam. In this paper, this assumption is relaxed. The governing equations of motion are derived. It has been shown that the off-axis center of mass of the attached mass generates an amplitude-dependent transverse force in the beam, which introduces a quadratic nonlinearity. The nonlinear governing equations of motion are solved using the Multiple Scales method. The nonlinear free vibration frequencies are determined.

Dynamics of Timoshenko Beams Conveying Fluid

1976 ◽  
Vol 18 (4) ◽  
pp. 210-220 ◽  
Author(s):  
M. P. Paidoussis ◽  
B. E. Laithier
Keyword(s):  
Equations Of Motion ◽  
Beam Theory ◽  
Present Theory ◽  
Timoshenko Beams ◽  
Bernoulli Beam ◽  
Finite Difference Technique ◽  
Observed Behaviour ◽  
Pipes Conveying Fluid ◽  
Euler Bernoulli Beam ◽  
Conveying Fluid

The dynamics of pipes conveying fluid is described by means of the Timoshenko beam theory. The equations of motion are derived and solved ( a) by a finite-difference technique, and ( b) by a variational method. It is shown that the latter is the more efficient method. The eigenfrequencies of the system and its stability characteristics are compared with results obtained previously using the Euler-Bernoulli beam theory, and it is shown that in certain cases (e.g. short pipes) the two sets of results diverge. Experiments indicate that the present theory is more successful in predicting the observed behaviour. Furthermore, the present theory shows that, in some cases, cantilevered pipes may lose stability by buckling, whereas previous theories indicate that the system always loses stability by flutter.

Dynamic Analysis of Three Parallel Beams With Electrostatic Force Interaction

2011 ◽  
Author(s):  
Pezhman A. Hassanpour ◽  
Patricia M. Nieva ◽  
Amir Khajepour
Keyword(s):  
Time Domain ◽  
Stability Condition ◽  
Initial Conditions ◽  
Electrostatic Force ◽  
Equations Of Motion ◽  
Beam Theory ◽  
Stability Margin ◽  
Modal Damping ◽  
The Stability ◽  
Euler Bernoulli Beam

In this paper, the dynamics of a micro-machined structure with three parallel cantilevers is investigated. The cantilevers are electrically charged and apply electrostatic force to each other. The governing equations of motion are derived using Euler-Bernoulli beam theory and considering structural modal damping. The stability condition of the beams for various electric charges is also studied. In addition, the equations of motion are integrated to obtain the response of the beams in time-domain for a range of initial conditions. This response is used to study the behavior of the beams at the stability margin. The end application of the structure under investigation is in the device characterization. The dynamic stability condition and time-domain responses are used to investigate the reliability of the characterization. Once translated back to physical quantities, these results can be used for improving the measurements.

Sign in / Sign up

Export Citation Format

Share Document