A study on automated ribbon bridge installation strategy and control system design

Thesis for the Degree of Doctor of PhilosophyA Study on Automated Ribbon Bridge Installation Strategy and Control System Design by Van Trong Nguyen Department of Mechanical System Engine

Thesis for the Degree of Doctor of Philosophy

A Study on Automated Ribbon Bridge Installation Strategy and

Control System Design

by Van Trong Nguyen

Department of Mechanical System Engineering

The Graduate School

Pukyong National University

October 2018

A Study on Automated Ribbon Bridge Installation Strategy and

Control System Design

부유식 교량 설치방법 및 제어시스템 구축에

관한 연구

by Van Trong Nguyen

Advisor: Prof Young-Bok Kim

A thesis submitted in partial fulfillment of the requirements for

the degree of Doctor of Philosophy

In Department of Mechanical System Engineering,

The Graduate School,Pukyong National University

October 2018

Foremost, I would like to express my sincere gratitude to myadvisor Professor Young-Bok Kim for the continuous support of mystudy and research, for his immense knowledge, motivation, patience,and his enthusiasm His endless kindness, insight supports, and strongmotivation encouraged and helped me to accomplish my research andfinish this dissertation scientifically With all my respect and frombottom of my heart, I wish my Professor and his family to have thelong-lived health and happiness

I would like to thank the members of my thesis committee: Prof.Suk-Ho Jung, Prof Soo-Yol Ok, Prof Jin-Ho Suh, and Dr Sang-Won Ji who have provided wonderful feedback on my work and greatsuggestions for better contribution of my dissertation

I am also grateful to Prof Kyoung-Joon Kim, my former Masteradvisor, and Dr Anh-Minh Duc Tran from Ton Duc Thang Universityfor essential assistances Without their introduction, I would not havethe chance to finish my study in Marine Cybernetics Laboratory.Besides, I would like to thank all members of Marine Cybernet-ics Laboratory for their cooperation, encouragement, and friendshipgiving me a comfortable and active environment to achieve my work:Manh Son Tran, Nhat Binh Le, Duc Quan Tran, Eun-Ho Choi, Dong-Hoon Lee, Dae-Hwan Kim, Mi-Roo Sin, Soumayya Chakir and allother foreign friends

Thanks are due to all members of Vietnamese Students’ tion in Korea, especially Dr Huy Hung Nguyen, Dr Van Tu Duong,

Associa-Dr Phuc Thinh Doan, Associa-Dr Viet Thang Tran, Associa-Dr Dac Chi Dang fortheir vigorous supports and invaluable helps.

I would like to thank my parents, my older sister and all my closerelatives for their encouragement throughout my life Without theirsupports, there will be a lot of difficulties for my to finish my graduatestudy seamlessly

Finally, I owe more than thanks to my wonderful wife Thuy LinhDang for her unconditional love, endless encouragement not only allthe time of my study but also in whole of my life ahead

Pukyong National University, Busan, Korea

October 26, 2018

Van Trong Nguyen

Acknowledgment i

Content iii

Abstract vi

List of Figures x

List of Tables xvi

Abbreviation xvii

Nomenclatures xviii

Chapter 1 Introduction 1

1.1 Background and motivation 1

1.2 Problem Statements 5

1.3 Objective and researching method 6

1.4 Organization of dissertation 8

Chapter 2 Induction of the Ribbon Bridge and Modeling 10 2.1 System description 10

2.1.1 Overview of the ribbon floating bridge 10

2.1.2 An automated installation and operation strategy for RFBs 11

2.2 The ribbon floating bridge model description 12

2.2.1 Mechanical design 12

2.2.2 Electrical design 15

2.3 The RFBs Modeling 20

2.3.1 General Modeling for Control of the RFBs 20

2.3.2 The Pilot Model of the RFB Modeling for Control Design 22

2.4 System Identification 25

2.5 Summary 29

Chapter 3 Observer-Based Optimal Control Design with Linear Quadratic Regulator Technique 30

3.1 Introduction 30

3.2 Control System Framework 31

3.3 Observer-based Control Design 35

3.3.1 State Observer Design 35

3.3.2 Optimal Controller Design 38

3.4 Simulation Results 42

3.5 Experimental Results 48

3.6 Summary 58

Chapter 4 Motion Control Performance with Sliding Mode Control Design 59

4.1 Introduction 59

4.2 Sliding Mode Control of MIMO Underactuated System 59 4.3 Simulation results 64

4.4 Experimental results 69

4.5 Summary 79

Chapter 5 Conclusions and Future Works 81

5.1 Conclusions 81

5.2 Future works 82

References 84

Publication and Conference 88

A Study on Automated Ribbon Bridge Installation Strategy and

Control System Design

Van Trong Nguyen

Department of Mechanical System Engineering,

The Graduate School, Pukyong National University

AbstractRecently, Ribbon Floating Bridges are widely utilized in trans-portation, especially for emergency restoration in both military andcivil fields thanks to their great advantages of ability to transportheavy combat vehicles, trucks, quick installation, and low environ-mental impacts Since the installation and operation of the ribbonfloating bridge are mainly carried by manual work, these jobs maycontain high risks, particularly in dangerous situation and combattime Therefore, it is critical to propose an installation strategy andself-operation automatically

This dissertation aims to present a new approach for automatedinstallation and operation of the ribbon floating bridge by proposing amathematical modeling and designing a control system with differentapproaches

The floating bridge system consists a series of interior and rambays connected that can be considered as the multi-link manipulator

It is confirmed that there is no previous study related to this objectalthough a lot of researchers paid attention to dynamic analysis Be-

sides, the floating bridge systems normally work in continuous ing environment and are affected by various of uncertainties such ascurrent flow, moving load, and other external disturbances that canlead to position displacement.

chang-To successfully achieve the automatic installation and self-correctionpositional displacement of the ribbon floating bridge, the integratedpropulsion systems are included and the yaw motion of every sin-gle bay is measured by the incremental encoder The ribbon floatingbridge is loaded in one riverside and then is rotated to the desiredposition across the river In order to maintain the structure and oper-ation of the bridge system, it is required to ensure the linearity of thewhole bridge and keep its desired position To completely performthese task, the followings are carried out:

● Firstly, the ribbon floating bridge system structure descriptionand dynamic analysis are discussed and system modeling of the rib-bon floating bridge consisting of five individual coupled floating units

is given In this system, there will be existences of two passive baysthat do not have propulsion systems The remaining three active baysare designed to integrate with three propulsion systems containingazimuth propellers, direct current motors and motor drivers Besides,the yaw displacement between two continuous floating units is mea-sured by the incremental encoder The system modeling of the rib-bon floating bridge describes the kinematics and kinetic of mechani-cal and electrical operation to obtain a dynamic system expressed bystate equations

● Secondly, a number of experimental studies is conducted in der to identify the dynamic characteristics of the floating unit Be-

or-sides, the propulsion system is also identified through variety of periments with different step inputs In order to estimate the affection

ex-of current flow disturbance, an experiment was carried out with eral assumed water velocities Among the obtained data, a represen-tative model is selected In addition, there are variety of states cannot

sev-be measured directly for feedback, therefore, it is necessary to clude a state estimator in control system The linear state observer isdesigned and implemented The effectiveness and robustness of theproposed state estimator are verified by numerical simulations andexperimental results

in-● Thirdly, an optimal controller using Linear Quadratic tor (LQR) technique is designed and implemented For the class ofMIMO linear system, the optimal control method is common usedfor robust achievement Based on previous proposed state observer,the controller gains are defined with the assistance of Matlab soft-ware To verify the sufficiency of the given observer-based controller,

Regula-a number of numericRegula-al simulRegula-ations with vRegula-arious desired outputs Regula-anddistinctive environmental conditions are investigated For further con-firmation of practical feasibility of the proposed installation strategyand control system, the experiment is executed in both calm waterbasin and under wave disturbance attack The obtained results indi-cate that the proposed control system satisfies the initial objectives

● Finally, although the optimal LQR based state estimator troller is eligible to achieve the desired control performance, therewill be a raised problem caused by the uncertainties of external dis-turbance leading to slow response of controller to cope with continu-ous wave/current flow force Hence, it is critical to improve the reac-

con-tion time of controller that quickly adapts with uncertainties as well

as external disturbance To eliminate with the unexpected attacks ofexternal disturbance and improve the reaction time, a sliding modecontroller (SMC) is proposed for under-actuated system Simulationand experimental results illustrate the effectiveness of the proposedcontroller including the ability to overcome continuous wave duringinstallation phase and the robust stable of position keeping phase

List of Figures

Fig 1.1 The actual ribbon bridge system 2

Fig 1.2 Conventional methods for ribbon bridge instal-lation 3

Fig 2.1 A proposed installation strategy for the ribbon bridge 12

Fig 2.2 Diagram of five-bay ribbon bridge model structure 13 Fig 2.3 Structure of the active bay 14

Fig 2.4 Structure of the passive bay 15

Fig 2.5 The configuration diagram of the control system 16

Fig 2.6 The photo and specification of the incremental encoder 16

Fig 2.7 The photo and specification of NI PXIe-6363 18

Fig 2.8 The photo and specification of NI PXI-6221 18

Fig 2.9 The photo and specification of NI PXI-6221 19

Fig 2.10 The photo and specification of DC motor 19

Fig 2.11 The photo and specification of the propeller 20

Fig 2.12 The structure of five-floating unit bridge system 23

Fig 2.13 The experiment setup for propulsion system identification 26

Fig 2.14 The input step voltage and the obtained output force 26

Fig 2.15 The fitting result of identified model for propul-sion system 27

Fig 2.16 The experiment setup for inertia and damping

coefficient identification 28

Fig 2.17 The least square data fitting result 28

Fig 3.1 The servosystem for positional control of the RFB system 35

Fig 3.2 The diagram of a full-state observer structure 36

Fig 3.3 The yaw angle deviation of floating unit no 1 43

Fig 3.4 The yaw angle deviation of floating unit no 2 43

Fig 3.5 The yaw angle deviation of floating unit no 3 43

Fig 3.6 The yaw angle deviation of floating unit no 4 44

Fig 3.7 The yaw angle deviation of floating unit no 5 44

Fig 3.8 The control input voltage for propulsion systems in ideal condition 44

Fig 3.9 The yaw motion of floating unit no 1 under disturbance 45

Fig 3.10 The yaw motion of floating unit no 2 under disturbance 46

Fig 3.11 The yaw motion of floating unit no 3 under disturbance 46

Fig 3.12 The yaw motion of floating unit no 4 under disturbance 46

Fig 3.13 The yaw motion of floating unit no 5 under disturbance 47

Fig 3.14 The control input for propulsion systems under disturbance 47

Fig 3.15 The experiment setup for RFB installation and

position keeping control 48Fig 3.16 The yaw motion of floating unit no 1 in calm

water 49Fig 3.17 The yaw motion of floating unit no 2 in calm

water 50Fig 3.18 The yaw motion of floating unit no 3 in calm

water 50Fig 3.19 The yaw motion of floating unit no 4 in calm

water 50Fig 3.20 The yaw motion of floating unit no 5 in calm

water 51Fig 3.21 The control input for propulsion systems in

calm water 51Fig 3.22 The yaw angle displacement between #1 unit

and #2 unit 52Fig 3.23 The yaw angle displacement between #2 unit

and #3 unit 52Fig 3.24 The yaw angle displacement between #3 unit

and #4 unit 53Fig 3.25 The yaw angle displacement between #4 unit

and #5 unit 53Fig 3.26 The yaw motion of unit #1 with external distur-

bance 54Fig 3.27 The yaw motion of unit #1 with external distur-

bance 54

Fig 3.28 The yaw motion of unit #1 with external

distur-bance 54

Fig 3.29 The yaw motion of unit #1 with external distur-bance 55

Fig 3.30 The yaw motion of unit #1 with external distur-bance 55

Fig 3.31 The control input for propulsion systems with external disturbance 55

Fig 3.32 The yaw angle displacement between #1 unit and #2 unit 56

Fig 3.33 The yaw angle displacement between #2 unit and #3 unit 56

Fig 3.34 The yaw angle displacement between #3 unit and #4 unit 57

Fig 3.35 The yaw angle displacement between #4 unit and #5 unit 57

Fig 4.1 Yaw angle deviation of floating unit #1 67

Fig 4.2 Yaw angle deviation of floating unit #2 67

Fig 4.3 Yaw angle deviation of floating unit #3 67

Fig 4.4 Yaw angle deviation of floating unit #4 68

Fig 4.5 Yaw angle deviation of floating unit #5 68

Fig 4.6 Force command inputs for propulsion systems 68

Fig 4.7 The yaw motion of unit #1 with SMC in calm water 70

Fig 4.8 The yaw motion of unit #1 with SMC in calm water 70

Fig 4.10 The yaw motion of unit #1 with SMC in calm

water 70Fig 4.9 The yaw motion of unit #1 with SMC in calm

water 71Fig 4.11 The yaw motion of unit #1 with SMC in calm

water 71Fig 4.12 The yaw displacement between unit #1 and unit

#2 with SMC in calm water 72Fig 4.13 The yaw displacement between unit #2 and unit

#3 with SMC in calm water 72Fig 4.14 The yaw displacement between unit #3 and unit

#4 with SMC in calm water 73Fig 4.15 The yaw displacement between unit #4 and unit

#5 with SMC in calm water 73Fig 4.16 The control forces generated by propulsion

system in calm water condition 74Fig 4.17 The yaw motion of unit #1 with SMC under

disturbance 75Fig 4.18 The yaw motion of unit #2 with SMC under

disturbance 75Fig 4.19 The yaw motion of unit #3 with SMC under

disturbance 75Fig 4.20 The yaw motion of unit #4 with SMC under

disturbance 76Fig 4.21 The yaw motion of unit #5 with SMC under

disturbance 76

Fig 4.22 The yaw displacement between unit #1 and unit

#2 under disturbance 77Fig 4.23 The yaw displacement between unit #2 and unit

#3 under disturbance 77Fig 4.24 The yaw displacement between unit #3 and unit

#4 under disturbance 78Fig 4.25 The yaw displacement between unit #4 and unit

#5 under disturbance 78Fig 4.26 The force commands generated by propulsion

systems under disturbance condition 79

List of TablesTable 2.1 Parameters of floating unit 14Table 2.2 Detailed specification of the PXIe-8115 em-

bedded controller 17

Abbreviation

-ci The damping coefficient of the joint

connect-ing the ithand the(i+1)th floating units

-Filu The spring forces at the upper left-hand-side N

Fild The spring forces at the lower left-hand-side N

Firu The spring forces at the upper right-hand-side N

Fird The spring forces at the lower right-hand-side N

Fip The force generated by the propulsion system N

Fiw The water current flow force attacking to each

floating unit

N

Iz The inertia moment of the floating unit on the

fixed z-axis

-kiu The stiffness coefficient of the upper

transla-tion spring connecting the ith and the(i + 1)th

floating units

N.m−1

kid The stiffness coefficient of the lower

transla-tion spring connecting the ith and the(i + 1)th

floating units

N.m−1

-Ti The external torque acting on the ithfloating

unit

N.m

-xiu The upper linear relative displacement between

the ith and the(i+1)thfloating units

-xid The lower linear relative displacement between

the ith and the(i+1)thfloating units

-wv The arms of propulsion and water current

forces

m

θi The yaw angle of the ith floating unit (in this

study, the counterclockwise is the forward

di-rection of rotation motion)

rad

˙

¨

θi The yaw acceleration of the ith floating unit rad.s−2

-Chapter 1 Introduction

With the dense network of water obstacles around the world such

as rivers, lakes, and channels, the demand of water crossing is gettingmore and more important Regarding the means of water obstaclecrossing, it may refer to several efficient methods [1] as follows:

• Bridging system is the most popular structure until now Interm of water crossing purpose, the bridge is constructed toconnect two sides of rivers, lakes, or even ocean There aremany designs of bridge systems that satisfy particular objec-tives or different conditions However, there are two main types

of bridges that can be considered as permanent bridges (fixedbridge) which are build in a place and the others are tempo-ral bridges that can be portable and rebuild in any necessaryplace The ribbon floating bridge, one particular kind of tem-poral bridge system, will be the major object of our study

• The second type should be tunnel The tunnel is far differentfrom other kinds of water obstacle crossing with the under-ground structure or dug through the surrounding soil/earth/rock

• Another type of popular water obstacle crossing is ferry Itsoperation is similar to the surface vessel but in short distanceand the main tasks are carrying passengers, vehicles, and cargoacross a body of water

In term of temporal bridging, the ribbon floating bridge [2], also

called foldable float bridge is great importance for transportation, pecially for emergency restoration in both military and civil fields.Compared to land-based bridges, there are variety of recognized ad-vantages such as the ability to transport heavy loads including ve-hicles, rapid installation, uncomplicated structure, and low environ-mental impacts The most significant characteristic that is only avail-able in this means of bridging is the ability to relocate thanks to itsgreat portability.

es-Fig 1.1 The actual ribbon bridge system

The ribbon floating bridge was developed in 1970s in both many by the former EWK and by the company in US and by NATOagreement it was decided to make both systems fully inter-operable.Since then, the ribbon floating bridges are commonly used in armyforce of different countries including Germany, Canada, Australia,

Ger-US, and so on with great success [3] The actual structure of the bon float can be seen at Fig 1.1 Most floating bridges are made from

rib-light-weight concrete, steel, aluminum alloys and composite als [4, 5] It is clearly seen that the ribbon floating bridge is designed

materi-to use buoyancy force materi-to resist itself weight as well as vehicular ing that reduces financial cost and increases the life span

load-Fig 1.2 Conventional methods for ribbon bridge installation

Regarding the construction process and operation of the ribbonfloating bridge, two leading factors that decide the success of theseprocess are safety and speedy The conventional installation process-ing is commonly done by manual works with the assistance of erec-tion boats and cable as seen in Fig 1.2 Each individual bay is carried

to the desired place and freely floated on water-body Then, the ators use supporting boats to connect them together making the longbridge To maintain the linearity of the bridge, many erection boatsand cables are employed handling by human force The time con-sumption is relatively long because of difficulties while the operatorsworking across the rivers or lakes Most of the ribbon floating bridgesare employed for quick restoration and process, especially in militaryservice In regular condition, the installation and operation of the rib-bon floating bridge with manual work may not have any difficulty.However, considering the hazard situations as combat/war time or

oper-dangerous case, it raises high risk for manual operation that can lead

to serious issues Therefore, it is critical to propose an advanced stallation strategy in which autonomous self-operated system should

in-be included to overcome the aforementioned cons and situations.When it comes to dynamic analysis of the ribbon floating bridge,variety of approaches have been proposed Wang et al [6] presentedthe dynamic behavior of the pontoon separated floating bridge undermoving load S Fu and W Cui [7] analyzed the dynamic displace-ment and connection force of the ribbon floating bridge A Rahman[8] studied the dynamic response of floating bridge with the trans-verse pontoons The majorities of the aforementioned studies are an-alyzing the dynamic response and structures of the floating bridges.However, it is critical to study about dynamic characteristics and ana-lyze the structure of the bridge system to establish the suitable math-ematical modeling for control design

Basically, the floating bridges have significant similarities of namics as water surface vehicles Thus, the problem of ribbon floatingbridge control can be considered as the further extension of specialwater surface floating units Various approaches have been recordedfor the surface vehicles and dynamic positioning The development of

dy-DP has been started since 1970s More advanced control techniquesbased on optimal control and observer was introduced by Balchen [9].Lately, Balchen et al [10] extended his previous work in 1980 Be-sides, Grimble [11] also developed the dynamic positioning controlsystem using stochastic optimal control theory Strand [12] presentedinteresting topics related to the positioning control for surface vesselbased on nonlinear control theory Fossen [13] introduced the general

solutions for vessel control system designs that mainly employed theactive propulsion systems for course tracking and station keeping.Moreover, a model-based control technique that provides both coursetracking and station keeping of ship is proposed by Sorensen [14].Katebi and co-authors [15] designed a DP system with robust con-troller.

Additionally, a significant number of researchers study about namics of propulsion systems and applications in marine system con-trol John gave the overview of marine propellers and propulsion sys-tem [16] Øyvind [17] and Damir [18] presented several topics re-lated to marine electrical power system and marine propeller con-trol Sørensen et al [19] introduced the torque and power control ofelectrically driven marine propellers Besides, Timothy reviewed thetrends in ship electric propulsion [20] that confirms the future of elec-tric use in marine vehicle control

dy-Although the popularity of using ribbon floating bridges for ing water bodies is increasing, information and research on this topicare rarely limited Yasuhiro and co-workers [21] introduced a newstudy on measurement system for positional displacement of floatingunits of pontoon bridges Most relevantly, Kim et al [22] proposedthe installation strategy for ribbon bridge that enables the possibility

cross-of designing the control system for the ribbon floating bridges

Based on aforementioned analyses, the problem statements to troduce a new autonomous installation strategy and control systemfor the ribbon floating bridge are described as follows:

in-• To introduce a new automated installation strategy of the ribbonfloating bridge to significantly decrease the high risk of manualjob Different ideas that can be implemented for the floatingbridge system are described.

• To establish the mathematical modeling of the ribbon floatingbridge which is using the active electrical propulsion systemsfor driving whole bridge to obtain the system dynamics ex-pressed by state equations

• To identify characteristic parameters and define the externalwater current disturbance The state estimator is designed based

on observability estimation

• To design a yaw motion controller based on LQR control nique combining with the pre-defined state observer The ef-fectiveness and robustness of controller have been verified bynumerical investigation and experimental conduction

tech-• To quickly cope with variety of disturbances and uncertainties,

a controller based on advanced control strategy of SMC hasbeen proposed The SMC controller for under-actuated systemhas been verified through different conditions of experimentstudies

1.3 Objective and researching method

The objective of this dissertation is to develop a control systememploying propulsion systems for automated installation and self-operation of the ribbon floating bridge to replace the manual work

which may contain difficulties and risky Two proposed based controllers have been presented to complete the following tasks:

observer-• The whole bridge will be rotated from the initial position by aparallel control actions: the yaw motion and yaw displacementamong floating units

• When the bridge reached the desired position (crossing the ter barrier), the main responsibility of the control system isensuring the linearity of the whole bridge by adjusting yawdisplacement among floating units under current water flow orwave force attacks

wa-To describe a ribbon floating bridge in mathematical model, chanical and electrical behaviors are being analyzed The essentialparameters appearing in the model will be identified by conductingexperiments and estimated by Matlab Identification Toolbox

me-To design an optimal controller based on LQR technique, a ear observer is defined to estimate the unmeasured states A series ofsimulations are investigated with different desired outputs and initialyaw angles under various conditions For further verification of pro-posed controller, an experimental model has been set up and appliedthe above-mentioned controller to simulate the actual processing ofbridge installation and operation

lin-For quick coping with external disturbances such as current flowand wave attack, an advanced controller applying SMC has been de-veloped The effectiveness and robustness of the proposed controllerare verified through simulation and experimental studies

The ribbon floating bridge system is modeled by five connectedindividual floating units with three out of five floating units are ac-tivated by electrical propulsion systems and the remaining two arepassive driven Five incremental encoders are attached to measure theyaw displacements The control system is implemented by employingthe National Instruments PXIe-8115 embedded controller equipped

by the acquisition card NI PXIe-6363 and PXI 6221 The controllersare programmed applying the NI Labview 2016 commercial softwarewith sample time of 0.03s The experiment results are presented andanalyzed to show the possibility, feasibility, robustness, and effective-ness of the proposed strategy and control system

1.4 Organization of dissertation

Chapter 1: Introduction

In this chapter, background and motivation of this dissertation aregiven Problem statements, objective and researching methods of thisdissertation are presented And the organization of this dissertation isshown

Chapter 2: Introduction of the Ribbon Bridge, Modeling, andIdentification

This chapter presents the structure of a ribbon floating bridgewhich has been widely implemented in service Then, a model usedfor modeling and experiment has been described After that, the mod-elings of the ribbon floating bridge system in scale model is obtainedfor control system design and used for this dissertation Since thesystem parameters of the ribbon floating bridge presented in previouschapter are unknown, by conducting necessary experiments, the es-

sential parameters are identified with the assistance of computationalsoftware.

Chapter 3:Observer-Based Optimal Control Design with ear Quadratic Regulator Technique

Lin-In this chapter, a yaw motion controller based on the optimal trol and state estimator is designed Since only the yaw angles can bemeasured directly, therefore, it is critical to obtain other state valu-ables Hence, the linear observer is designed base on observabilityestimation The effectiveness of the proposed observer has been ver-ified by simulation investigation A servo-system for position con-troller is introduced to precisely control the yaw displacement amongfloating units as well as yaw motion of the whole bridge The simula-tion and experimental results depict the effectiveness of the proposedapproach

con-Chapter 4: Motion Control Performance with Sliding ModeControl Design

Chapter 4 proposes the sliding mode controller design for actuated ribbon bridge system The sliding mode control law guar-antees both fast response and robustness of desirable performance ofposition keeping under environmental disturbances In combinationwith the pre-defined observer, the sliding mode controller shows theoutstanding control performance verified by both numerical investi-gation and experimental studies

under-Chapter 5: Conclusion and Future Study

The major research results of this study are summarized and gestions for further research are presented

sug-Chapter 2 Induction of the Ribbon Bridge and

Modeling

This chapter describes the structure of a ribbon floating bridge,summarizes the conventional installation, operation, and its difficul-ties From then, new automated approaches to improve these limita-tion are introduced By studying system mechanism, the mathemat-ical modeling of a ribbon floating bridge is obtained for designingmotion controller in this dissertation

2.1 System description

2.1.1 Overview of the ribbon floating bridge

The ribbon floating bridge (RFB), also named as foldable floatbridge, is a modular bridge having single-lane or two-lane way that

is supported by a floating integral superstructure made of aluminumwhich acts as a pontoon The bridge system consists of interior andram bays that can be assembled and disassembled simply and beingtransported by trucks, helicopters, aircrafts, and railway cars whenfolded Once entering the water surface, the ribbon bay automaticallyopens to form the bridge or ferry type Conventionally, the ribbonsegments are driven by erection boats or human power with assis-tance of cable Then, workers will link individual bays together bymechanical locks and couplings

The RFBs are designed to carry heavy combat vehicles, trucks as

a floating bridge or ferry There are number of outstanding tages of the RFBs in comparison with conventional bridge systemsincluding: quick installation, simple structures, and low environmen-

advan-tal impacts In addition, the only behavior available in this type ofbridging is the ability to relocation thanks to its great portability.However, a number of limitations regarding the installation andoperation of the RFBs have been mentioned in Chapter 1 To over-come those difficulties, an automated solution is proposed in nextsection.

2.1.2 An automated installation and operation strategy for RFBs

As aforementioned, manual operation of RFBs installation andoperation is both low safety and slow speedy that leads to high risk

of operators and equipment, especially in case of dangerous tion or combat time Therefore, it is necessary to provide a properautonomous driving system for both installation and operation of theRFBs As can be seen from Fig 2.1, this study presents a new strat-egy to carry out the task of automated control of the RFBs by yawmotion control The whole process can be explained as follows:

situa-• The RFB will be loaded in one side of the water body by necting the ram bays and interior bays When the whole bridge

con-is constructed, it will be driven to the desired position across thewater body to connect two sides of the obstacle In this stage,the controller has the responsibility of maintain the linearity

of the bridge by correcting the displacement among floatingunits Simultaneously, the bridge must be brought to the targetsmoothly

• In next stage, the control system has to keep the whole bridge inthe target position and ensure the linearity of the bridge Underexternal disturbances as current flow, wave attack, and moving

loads, it requires the stability and quick adaption of the troller.

con-2.2 The ribbon floating bridge model description

This study focuses on installing and operating the RFBs by fullyautomated control system employing the propulsion systems To han-dle this issue, the mechanical and electrical designs are presented.2.2.1 Mechanical design

For modeling, a ribbon floating bridge system consisting five bon bays is designed as shown in Fig 2.2 There are three active bays

rib-Fig 2.1 A proposed installation strategy for the ribbon bridge

Fig 2.2 Diagram of five-bay ribbon bridge model structure

that will be driven by propulsion systems The remaining bays will

be passively driven by the coupling relation Detailed descriptions of

an active bay and a passive bay are illustrated in Fig 2.3 and Fig 2.4,respectively

Generally, five floating units have the similar structure and sion in length, width, height, and weight Each single bay has twoadjustable slots located in left and right hand-side for inserting theconnectors There are four additional axises with integrated holes forinserting springs The detail parameters can be found in Table 2.1.All bays are made by acrylic, type of polymer material The activeunit is designed with additional bases for placing electrical controlparts including DC motor, motor drive, and propeller

dimen-In contrary, the passive unit does not contain additional parts asthe active one Therefore, to maintain the balance in term of weight,

Fig 2.3 Structure of the active bay

Table 2.1 Parameters of floating unit

the additional weight must be inserted

To connect five floating units, it is critical to include the tors The designs of connectors can be found in Fig 2.2 As can beseen, there are two different structures using in left-side and right-

connec-Fig 2.4 Structure of the passive bay

side of each bay The connector using for the left-side has the axisthat should be coupled with axis of the incremental encoder On right-side, there will be an additional part for keeping the encoder safe fromwater For accurate measurement, it is required that the connectors arefreely motion

2.2.2 Electrical design

A structure of control system employed in this study is presented

in Fig 2.5 The proposed control system of the RFB is designed asclose-loop system comprised of sensor, controller, and actuator parts

Fig 2.5 The configuration diagram of the control system

The sensor part contains five incremental encoders attached tothe connector between each couple of floating units to obtain the yawmotions for feedback to the controller The detailed specifications ofthe encoder are given in Fig 2.6

Fig 2.6 The photo and specification of the incremental encoder

The configuration of control part used for controlling the RFBsystem is shown in Fig 2.5 The proposed controller is composed of

the industrial National Instrument computer and the DAQ cards.The National Instrument PXIe-8815 embedded controller build inthe PXIe-1078 chasis is employed for main controller to implementcontrol algorithms For communication, the main controller is sup-ported by data acquisition cards PXIe-6363 and PXI-6221 in order toget signals from encoders and deliver control signals including digi-tal signals and voltage signals to the actuators Specifications of theembedded controller are given in Table 2.2.

Table 2.2 Detailed specification of the PXIe-8115 embedded

controller

The specification and real structure of the DAQ cards PXIe-6363and PXI-6221 are shown in Fig 2.7 and Fig 2.8 , respectively.The actuator part is comprised of motor drivers, DC motors, androtated propellers Each DC motor is controlled by a motor driverKDC248H 12 24V with the analog signal sent from main controllervia DAQ card The specifications and photograph of the motor driveare given in Fig 2.9

In this study, the Graupner Speed 700BB Turbo 12V Brushed