7/24/2019 Fish Robot Introduce

http://slidepdf.com/reader/full/fish-robot-introduce 1/15

INTRODUCTION

Applications in underwater environment covers major areas such as ocean exploration,

search and rescue mission, pipelines and sea mining operation which can be effectively

executed with the employment of devices capable of underwater locomotion. In many

cases, the missions in the underwater environment are dangerous or complex and

inaccessible by humans. Therefore, such operation could be intelligently accomplished by

autonomous or remotely operated vehicle or devices.

Research on autonomous underwater devices leads back to !"# and since then, some

thirteen of such devices were successfully developed by the !! $%lidberg et al  ., !!&.

'owever, studies showed that underwater autonomous device(s moving ability tend to focus

on traditional techni)ue using propellers to generate the thrust for locomotion $*guyen et

al  ., +#a&. -urthermore, small propellers driving devices had mechanism deficiency

limitations underwater $ohammadshahi  et al  ., +##/&. Applications in underwater

environment re)uire devices that can combine both high cruising speed and good

maneuverability and propeller driven type had shown the limitation to combine both of the

abilities $%arrett et al  ., !!!&.

'owever, in the area of underwater biomimetic locomotion, especially fish0like propulsion, it

is possible to provide a mechanical mobile platform to achieve the response of high cruising

speed and good maneuverability. The fish swimming techni)ues of propulsion holds the

very key for improving the propulsion performance $Triantafyllou and Triantafyllou, !!1&.

Among various underwater biomimetic locomotion creatures, fish appears to combine theagility in a single embodiment. Therefore, by implementing such natural fish swimming

ability to the device would be an ideal method. In mother nature, however, most creatures

possesses complex biological system not as limited by the stiff mechanism and standard

discrete implementation in the men made devices $Anderson et al  ., !!/2 %arrett et al  .,

!!!2 3u et al  ., +##4&.

MORPHOLOGY AND SWIMMING MODES OF AQUATIC ANIMAL

*atural life of a)uatic creature had inspired researchers to study in particular the fishes as

model for designing fish0like devices. Therefore, it is crucial to understand and characterisethe fish locomotion in li)uid environment which conceal the constraint re)uired for

designing the devices. -ish morphological features are a critical identification for the first

purpose of the locomotion to match the engineering needs. -igure  illustrates the basic fish

morphological features.

7/24/2019 Fish Robot Introduce

http://slidepdf.com/reader/full/fish-robot-introduce 2/15

-ig. 5 -ish morphology $6fakiotakis et al  ., !!!&

-ig. +5 -ish locomotion associated with %7- propulsion $8indsey, !9/&

:ray $!& investigated the fish locomotion by capturing series of photographs to record

the form and position of the fish swimming motion at a known interval of time and found

that the lateral wave of a fish body travels from head to tail. According to ;ang et al  . $+##/&,

fish generated trust using their bodies to push the water away to behind and moving

forward. This being by momentum transferred from the fish(s body to the surrounding

water $;ang et al  ., +##/&. *guyen et al  . $+#b& had also discovered that real fish actually

changes its body shape for movement, whenever the fish body shape changes it creates

propulsion force for the fish to move forward or backward.

<ifferent types of fishes had been found to utili=e different modalities for swimming.6fakiotakis provided a review of fish locomotion underwater by classifying fish locomotion

techni)ues into five modes for the fish using their body and>or caudal fin $%7-& locomotion

to swim as illustrated in the -ig. + $8indsey, !9/2 6fakiotakis et al  ., !!!2 *guyen et al  ., +#a&.

MECHANISMS OF FISH SWIMMING MODALITIES

In undulatory %7- locomotion, there are four modes of fish swimming techni)ues based on

the length of fish tail fin and the oscillation strength. The anguilliform swimming $-ig. a&

applies to fish with long and slender body like eel and lamprey. These types of fish

generates propulsion using their body muscle wave from head to tail which produces a littleincrease in amplitude of the flexion wave as it pass along the body. The entire fish body

shape can bend at least one half of sine wave and when swimming, the amplitude of the

tail section being larger as compared to the head section. Also, anguilliform swimmer has

ability to swim backward $-ig. b& which re)uired the wave to be passed from tail to head

$:ray, !&.

7/24/2019 Fish Robot Introduce

http://slidepdf.com/reader/full/fish-robot-introduce 3/15

-ishes swam, by implementing subcarangiform swimming mode $-ig. 4& is able to increase

in wave amplitude by using the rear half of its body to generate the propulsion. -ishes such

as whiting, trout and salmon utili=es this type of swimming mode to swim which have

stiffer body to allow swimming at higher speed with reduced maneuverability.

-ig. $a0b&5 $a& -orward swim of a butterfish and $b&%ackward swim of eel $:ray, !&

-ig. 45 -orward swim of a whiting fish $:ray, !&

In fishes, swim by using carangiform swimming mode, also have stiffer body and can swim

faster if compared to the anguilliform and subcarangiform swimming modes as shown in

the -ig. 1. The reason being the majority of the fish movement is concentrated on the rear

body and tail. Therefore, this type of swimmer generally produced rapidly oscillating tail

7/24/2019 Fish Robot Introduce

http://slidepdf.com/reader/full/fish-robot-introduce 4/15

motion. -ishes like carp and swordfish are some that utili=es this type of swimming mode.

6wimmers like mackerel, tuna and shark are high0speed and long distance swimmer. This

type of fishes categori=ed as the thunniform swimming mode, $-ig. "&, has movement

mostly concentrates at the tail and so, has large and crescent shape tail.

-inally, the fishes that swim by implementing the ostraciiform swimming mode $-ig. 9&, is

the only classification in oscillatory %7- locomotion. The fishes utili=ing this type of mode

are such as boxfish and cowfish which have to rapidly oscillate their caudal fin for

movement while the body remains essentially rigid.

-ig. 15 -orward swim of a carp fish $*ilas et al  ., +#&

-ig. "5 -orward swim of mackerel fish $:ray, !&

7/24/2019 Fish Robot Introduce

http://slidepdf.com/reader/full/fish-robot-introduce 5/15

-ig. 95 -orward swim of boxfish

Although, this type of fish is known as slow swimmer but a study showed that this fish is

featured with high level of dynamic stability and high endurance $?odati and <eng, +##"&.

MODELLING AND SIMULATION

6tudies on fish swimming dynamics provided an understanding for developing biomimetic

robotic fish modeling and analy=ing as a mathematical system. The theoretical fish

locomotion can be divided into two parts, first the kinematics which treats only the

geometric aspect of the motion and secondly the kinetics which is the analysis of forces

causing the motion behaviour $eriam and ?raige, +#+&.

8ighthill $!"#& utili=es the trajectory approximation method and proposed the elongated

body theory for carangiform kinematic model. This model has been widely used in

biomimetic devices by the research community $Alvarado, +##92 %arrett et al  .,

!!!, !!"2 %arrett, !!"2 7ho, !!92 8iu and 'u, +##2 6hao et al  ., +##/2 Alvarado and 3oucef0

Toumi, +##"2 3an et al  ., +##/2 3u et al  ., +##42 3u and ;ang, +##1&.-igure / demonstrates the top

view of the fish swimming kinematics in two dimensions.

This mathematical model of the fish swimming kinematics could be expressed as5

$&

where, h$x, t& is the lateral displacement of the fish tail from the undulation central along

x0axis direction of the tail length at time t, cis the linear wave amplitude envelope and

chosen to be independent c+ is the )uadratic wave amplitude envelope for doubling the

amplitude of motion, both of the parameters are adjustable parameters. Respectively, k is

the tail wave number which is e)uals to +@>, where is the wavelength and B is the body

wave fre)uency e)uals to +@>. -igure ! is an illustration of fish propulsion wave base on

the C).  and according to %arrett et al  . $!!"&, sinusoidal propulsion wave travels from the

7/24/2019 Fish Robot Introduce

http://slidepdf.com/reader/full/fish-robot-introduce 6/15

right to left.

-ig. /5 Top view of fish swimming kinematic

-ig. !5 -ish swimming motion generated by AT8A% software

-ig. #5 echanical skeleton of multi0joint biomimetic devices$3u and ;ang, +##1&

In general, researches on multi0joint biomimetic device utili=ed C).  for modeling mimetic

fish0like behavior in the swimming motion. 8iu and 'u $+##& had designed multi0joint

carangiform swimming mode by converting C).  into a tail motion function which describes

the tail motion relative to the head and discreti=ed into a series of tail posture over time. 3u

7/24/2019 Fish Robot Introduce

http://slidepdf.com/reader/full/fish-robot-introduce 7/15

and ;ang $+##1& numerically calculated optimal link0length0ratio using improved constrained

cyclic variable method to apply in the development of a 40linked biomimetic device is as

illustrated in the -ig. #. 3an et al  . $+##/& had also developed a 4 <egree of -reedom $<D-&

carangiform biomimetic device and experimentally investigated the influence of

characteristic parameters including the fre)uency, amplitude, wavelength, phase difference

and coefficient of forward velocity.

Another method by %eam Theory utili=es the tail section of the biomimetic device to

modelled fish motion as a dynamic bending beam underwater $Timoshenko, !94&. The

governing e)uation of the model $-ig. &, is derived using this theory to yield as following

in C). +5

$+&

-ig. 5 7ontinuous flexible tail model

where, E is the material density of robotic fish tail and C is the 3oung(s modulus of elasticity

which are constants. The cross0section area A$x& and the inertia moment I$x& of cross0

section area of tail are a function of x. 7ombined C$x&I$x& term then yields the beam

bending stiffness. The $t& being time varying moment applied at distance a. The

distributed forces f$x, t& is used to generali=e the possible actuation input forces. The 8y$x,

t& term then relates the resistive interaction occurred due to interaction with the fluid

environment.

A continuous flexible tail instead of multi0joint rigid bar had also been studied $<aou et al  .,

+#2 Alvarado and 3oucef0Toumi, +##, +##"&. The continuous flexible tail mechanism is

simple, mechanically robust, better performance, simple control techni)ue, easy to seal

and protect sensitive parts $3ang et al  ., +#&. 6imilarly, Alvarado and 3oucef0Toumi

$+##"& developed a compliant body biomimetic fish $-ig. &, by using one servo0motor for

propulsion. They utili=e the C). + to achieve the lateral motion of tail by determining the

vibrations of the beam from the effect of internal and external forces which are related to

the material, geometry and actuator properties.

As well as, *guyen et al  . $+#a& analy=ed reactive forces and resistive forces in order to

7/24/2019 Fish Robot Introduce

http://slidepdf.com/reader/full/fish-robot-introduce 8/15

derive C). + model for non0uniform flexible tail of robotic fish. 'owever, they discovered

that the coefficients of this e)uation were not constant due to the non0uniform beams but

the analytical solution was used to describe the lateral movement of the flexible tail and to

obtain the material, geometry and actuator properties.

CONTROL SYSTEM FOR UNDERWATER IOMIMETIC DE!ICE

The history of underwater biomimetic robotics dated back to the RoboTuna. To understand

the %7- swimmer, %arrett $!!4& built the RoboTuna replica to the real tuna fish $-ig. +&. It

was designed to mimic actual tuna kinematics as close as possible using the reverse

engineering. ovement of the tail was controlled by seven vertebrae backbone connected

by six joints. Cach joint is actuated by cables and driven by six large <igiplan %8481%0#

brushless servo motors design by Farker 'annifin. These servo motor was hosted and

supervise by the control command of 4/"0computer at top0level while at mid0level a "0axis

<igital 6ignal Frocessor $<6F& card design by otion Cngineering Inc $CI& synchroni=e

with the host for control and receive feedback. Cach servo motor is attached with optical

encoder 6T7>+", connected to a matching Farker 'annifin %891 brushless servo amplifier

driver to actuation the system. -igure  is a simplify body motion control hardware of

RoboTuna, consisting of computer host synchroni=e with the <6F for control and receive

feedback of servo motor. -or waterproofing, the entire body was covered by 8ycra sock.

*umerous sensors were also connected to five computers to measure the drag force,

tor)ue and pressure for monitoring the control and to record the parameters $%arrett,

!!"&.

After RoboTuna, <raper 8aboratories developed the Gorticity 7ontrolled Hnmanned

Hnderwater Gehicle $G7HHG&.

7/24/2019 Fish Robot Introduce

http://slidepdf.com/reader/full/fish-robot-introduce 9/15

-ig. +5 Internal structure and control system of RoboTuna $%arrett, !!4&

-ig. 5 6implified body motion control hardware of RoboTuna

-ig. 45 Gorticity 7ontrolled Hnmanned Hnderwater Gehicle $G7HHG& system layout$Anderson and 7hhabra, +##+&

7/24/2019 Fish Robot Introduce

http://slidepdf.com/reader/full/fish-robot-introduce 10/15

-ig. 15 F7>#4 6tack of Gorticity 7ontrolled Hnmanned Hnderwater Gehicle $G7HHG&

ajor subsystem of the G7HHG included internal components, pressure hull, tail0drive

system and tail surface $-ig. 4&. The G7HHG tail movement, supported by five vertebrae

backbone with four joints, is controlled by a closed loop hydraulic system $7ho, !!9&.6urrounding of tail link is coated by epoxy polyvinyl chloride $FG7& foam disks to provide

buoyancy and flexibility. 8ike RoboTuna, the G7HHG flexible body was cover by 8ycra

bonded with neoprene rubber for waterproofing.

The front section of G7HHG body contains the electronics and hydraulic system and the

back tail section contains the actuation mechanism. The hydraulic system consists of a

reservoir, a small positive displacement pump, a pressure accumulation vessel, four servo

vales and four cylinders. Actuation mechanism of three aluminium links with tail fin is

driven by hydraulic cylinder. To control the actuation, F7>#4 stack $-ig. 1&, read and

process pressure sensor feedbacks from each cylinder and sends command to the hydraulic

system to the tail. In F7>#4, the 4/"0computer functions to coordinate the actuation

operation and log the data and an ethernet module for reprogram and communicate with

4/". The <6F synchroni=e and receive command from 4/" for control of the actuation. <6F

read and filter the analog signal from the actuation system sensor then convert signals to

digital signal sent commands to the hydraulic power unit and servo valves for moving the

cylinders and actuate the tail.

Another IT RoboFike robotic swimmer had a tail movement supported by four vertebrae

backbone and three joints controlled by cables driven by high tor)ue airplane servo motor

model !# manufacture by -utaba, $?umph, +###&. The skin of RoboFike is made from

compliant silicone rubber to seal and protect the internal component $-ig. "&. The actuator

control system, consisting of otorola "/+ computer base on Tattletale odel / design

by Dnset 7omputer Inc. RoboFike do not have sensor feedback like RoboTuna and G7HHG.

Therefore, the otorola "/+ receives command from the computer host to actuate the

servo motors for the tail at 9# '= in sine wave and control of pectoral fin $-ig. 9&, to move

each of the pulley joint in sinusoidal swimming motion. The RoboFike was able to swim at a

7/24/2019 Fish Robot Introduce

http://slidepdf.com/reader/full/fish-robot-introduce 11/15

maximum speed of #. 8 sec0 at '= of tail beat fre)uency.

-ig. "5 8ayout of RoboFike $?umph, +###&

-ig. 95 RoboFike actuator control flow

-ig. /5 <esign of a complaint body biomimetic robotic fish $Alvarado, +##9&

A small complaint body biomimetic fish for swarm operation was also invented $Alvarado,

+##9&. %ase on shark geometry $-ig. /&, one high tor)ue '6R1!!1T: 'itech motor was

7/24/2019 Fish Robot Introduce

http://slidepdf.com/reader/full/fish-robot-introduce 12/15

used to actuate the tail and two small -utaba servo motor to individually control the

pectoral fins. The body was made from moulded silicon with embedded servo motor for

driving the tail mechanism. The servo motor oscillation produces a travelling wave for the

fish body locomotion. In control $-ig. !&, it consists of a Flugapod <6F1"-/#

microcontroller from *ewicros or -utaba transmitter radio controller. The computer host

sent command signal to Flugapod microcontroller by Radio -re)uency $R-& form using

ee%ee Fro R- module as servo motor controller. 'owever, the -utaba radio transmitter

was modify to transmit sinusoidal or triangular wave form for servo motor control in

desired fre)uency tail beat.

-ig. !5 7ontrol flow of Alvarado robotic fish

Alvarado had also designed various compliant body prototypes in his study and one of the

prototypes could reach speed of 8 sec0 at .1 '= of tail beat fre)uency.

CONCLUSION

The review of underwater biomimetic devices development found that the limitation to

performance as compared to nature still lacks in the suitability of materials, mechanisms

and control. Cvolution of biological animal is far more advance and complex in functionality.

In the man0made design of biomimetic devices, it still faces the constraint of using

effective muscle and bone for actuation and to produce the necessary power and strength

for locomotion and maneuverability. Technological self0actuating materials could be

developed for such application to outperform biological muscles and bones for a better and

more natural control system instead of electro0mechanical system.

AC"NOWLEDGMENT

The authors wish to express their appreciation to the aterials and inerals Research Hnit,

-aculty of Cngineering, Hniversiti alaysia 6abah for the support of this study.

REFERENCES

7/24/2019 Fish Robot Introduce

http://slidepdf.com/reader/full/fish-robot-introduce 13/15

Alvarado, F.G. and ?. 3oucef0Toumi, +##. odeling and design methodology of an efficient

underwater propulsion system. Froceedings of the IA6TC< International 7onference on

Robotics and Applications, June +10+9, +##, 6al=burg, Austria, pp5 "0"".

Alvarado, F.G. and ?. 3oucef0Toumi, +##". <esign of machines with compliant bodies forbiomimetic locomotion in li)uid environments. J. <yn. 6yst. eas. 7ontrol, +/5 0.

7rossRef   K <irect 8ink  K

Alvarado, G.3., +##9. <esign of biomimetic compliant devices for locomotion in li)uid

environments. Fh.<. Thesis, <epartment of Dcean Cngineering, assachusetts Institute of

Technology, %ostan, assachusetts, H6A.

Anderson, J., ?. 6treitlien, <.6. %arrett and .6. Triantafyllou, !!/. Dscillating foils of high

propulsive efficiency. J. -luid ech., "#5 409+.

7rossRef   K <irect 8ink  K

Anderson, J.. and *.?. 7hhabra, +##+. aneuvering and stability performance of a

robotic tuna. Integr. 7omp. %iol., 4+5 /0+".

7rossRef   K <irect 8ink  K

%arrett, <., !!4. The design of a flexible hull undersea vehicle propelled by an oscillating

foil. asterLs Thesis, <epartment of Dcean Cngineering, assachusetts Institute of

Technology, %ostan, H6A.

%arrett, <., !!". Fropulsive efficiency of a flexible hull underwater vehicle. Fh.<. Thesis,

<epartment of Dcean Cngineering, assachusetts Institute of Technology, %ostan, H6A.

%arrett, <., . :rosenbaugh and . Triantafyllou, !!". The optimal control of a flexible

hull robotic undersea vehicle propelled by an oscillating foil. Froceedings of 6ymposium on

Autonomous Hnderwater Gehicle Technology, June +0", !!", onterey, 7A., pp5 0!.

%arrett, <.6., .6. Triantafyllou, <.?.F. 3ue, .A. :rosenbaugh and .J. ;olfgang,

!!!. <rag reduction in fish0like locomotion. J. -luid ech., !+5 /0++.

7rossRef   K <irect 8ink  K

%lidberg, <.R., R.. Turner and 6.:. 7happell, !!. Autonomous underwater vehicles5

7urrent activities and research opportunities. Rob. Autonom. 6ys., 95 !01#.

7rossRef   K <irect 8ink  K

7ho, J.8., !!9. Clectronic subsystems of a free0swimming robotic fish. asterLs Thesis,

7/24/2019 Fish Robot Introduce

http://slidepdf.com/reader/full/fish-robot-introduce 14/15

<epartment of Dcean Cngineering, assachusetts Institute of Technology, %ostan, H6A.

<aou, '.C.8., T. 6alumae and A. Ristolainen, :. Toming, . 8istak and . ?ruusmaa,

+#. A bio0mimetic design of a fish0like robot with compliant tail. Froceedings of the

International ;orkshop on %io0Inspired Robot, April "0/, +#, *antes, -rance, pp5 109.

:ray, J., !. 6tudies in animal locomotion5 I. The movement of fish with special

reference to the eel. J. Cxp. %iol., #5 //0#4.

<irect 8ink  K

?odati, F. and M. <eng, +##". %io0Inspired Robotic -ish with ultiple -ins. In5 Hnderwater

Gehicles, In=artsev, A.G. $Cd.&. InTech, Gienna, Austria.

?umph, J.., +###. aneuvering of a robotic pike. asterLs Thesis, <epartment of Dcean

Cngineering, assachusetts Institute of Technology, %ostan, assachusetts, H6A.

8ighthill, .J., !"#. *ote on the swimming of slender fish. J. -luid ech., !5 #109.

7rossRef   K <irect 8ink  K

8indsey, 7.7., !9/. -orm, -unction and 8ocomotory 'abits in -ish. In5 -ish Fhysiology,

'oar, ;.6. and <.J. Randall $Cds.&. Gol. 9, Academic Fress, *ew 3ork, *3., H6A., pp5 0##.

8iu, J. and '. 'u, +##. %iological inspiration5 -rom carangiform fish to multi0joint robotic

fish. J. %ionic Cng., 95 104/.

7rossRef   K <irect 8ink  K

eriam, J. and 8. ?raige, +#+. Cngineering echanics5 <ynamics. +th Cdn., Frentice 'all,

*ew Jersey, H6A., Fages5 91+.

ohammadshahi, <., A. 3ousefi0?oma, 6. %ahmanyar and '. aleki, +##/. <esign,

fabrication and hydrodynamic analysis of a biomimetic robot fish. Froceedings of the #th

;6CA6 International 7onference on Automatic 7ontrol, odelling and 6imulation, ay +90

#, +##/, Istanbul, Turkey, pp5 +4!0+14.

*guyen, F.8., G.F. <o and %.R. 8ee, +#. <ynamic modeling and experiment of a fish robot

with a flexible tail fin.. J. %ionic Cng., #5 !041.

7rossRef   K

*guyen, F.8., G.F. <o and %.R. 8ee, +#. <ynamic modeling of a non0uniform flexible tail

for a robotic fish. J. %ionic Cng., #5 +#0+#!.

7/24/2019 Fish Robot Introduce

http://slidepdf.com/reader/full/fish-robot-introduce 15/15

7rossRef   K <irect 8ink  K

*ilas, F., *. 6uwanchit and R. 8umpuprakarn, +#. Frototypical robotic fish with swimming

locomotive configuration in fluid environment. Froceedings of the International ulti

7onference of Cngineering and 7omputer 6cientists, Golume +, arch "0/, +##, 'ong?ong 0.

6fakiotakis, ., <.. 8ane, J.%.7. <avies, !!!. Review of fish swimming modes for a)uatic

locomotion. ICCC J. Dceanic Cng., +45 +90+1+.

7rossRef   K

6hao, J., 8. ;ang and J. 3u, +##/. <evelopment of an artificial fish0like robot and its

application in cooperative transportation. 7ontrol Cng. Fract., "5 1"!01/4.

7rossRef   K <irect 8ink  K

Timoshenko, 6., !94. Gibration Froblems in Cngineering. +nd Cdn., <. Gan *ostrand

7ompany, Inc., *ew Jersey, H6A., Fages5 49".

Triantafyllou, .6. and :.6. Triantafyllou, !!1. An efficient swimming machine. 6ci. Am.,

+9+5 "409#.

<irect 8ink  K

;ang, ., :. 'ang, J. 8i, 3. ;ang and ?. Miao, +##/. A micro0robot fish with embedded

6A wire actuated flexible biomimetic fin. 6ensors Actuators A5 Fhys., 445 140"#.

7rossRef   K <irect 8ink  K

3an, N., . 'an, 6.;. hang and J. 3ang, +##/. Farametric research of experiments on

a Carangiform robotic fish. J. %ionic Cng., 15 !10#.

7rossRef   K <irect 8ink  K

3ang, 8., 3. 6u and N. Miao, +#. *umerical study of propulsion mechanism for oscillating

rigid and flexible tuna0tails. J. %ionic Cng., /5 4#"049.

7rossRef   K <irect 8ink  K

3u, J. and 8. ;ang, +##1. Farameter optimi=ation of simplified propulsive model for

biomimetic robot fish. Froceedings of the ICCC International 7onference on, Robotics and

Automation, April /0++, +##1, %arcelona, 6pain, pp5 #"0.

3u, J., . Tan, 6. ;ang and C. 7hen, +##4. <evelopment of a biomimetic robotic fish and

its control algorithm. ICCC Trans. 6yst. an 7yber. Fart %5 7yber., 45 9!/0/#.