Development of Training Simulator for Sway Suppression Skills on

Shipboard Rotary Cranes

Yusaku Matsuda, Shoma Fushimi and Kazuhiko Terashima

Toyohashi University of Technology, The Mechanical Engineering Department,

System and Control laboratory, Hibarigaoka 1-1, Tempaku town, Toyohashi city, Japan

Keywords:

Ship control, Training, Industrial control, Human-machine interface, Teaching, Virtual reality.

Abstract:

In this paper, we develop the operational training system by teaching control input to crane operators. In

particular, it is applied to the sway suppression control of load, by utilizing optimal control input. If crane op-

erators can replicate its control input, they can operate crane suppressing the load sway, and hope the advance

of training effect. Firstly, we build a shipboard rotary crane simulator, and verify the validity of the training

simulator by transfer simulation. Nextly, it presents a sway suppression control method to obtain control input

for crane operators, and proposes the training system to teach its control input to operators. Finally, the crane

simulator integrates this training system, and the proposed training system veriﬁes the validity by subjects

experiments.

1 INTRODUCTION

A shipboard crane that is equipped on the ship is

widely used for cargo work in harbors or construc-

tion sites. Many kinds of shipboard crane are such as

small crane salvage barge that is several hundred tons;

bucket dredger that is used for digging or removing

mud and sand; and large non-sailing crane barge that

is thousands of tons. Recently, shipboard crane have

become larger for construction of pipeline, installa-

tion of caisson or offshore work in harbor or seacoast.

Generally, large shipboard crane had no rotary func-

tion. However, rotary shipboard crane that is effec-

tive for work has also become larger recently. Large

shipboard crane is required quick working, because

you must pay out very expensive anchorage charges.

So, it is required that the sway of the load is sup-

pressed and you transport it quickly. However, these

were depended heavily on the technique of skilled

operator. Additionally on the shipboard, ship sway

is also generated by wave and crane motion. Thus,

operators must consider these matters and operation

is very difﬁcult. On the other hand, operation work

of a crane is considered to be typical one of heavy,

dirty and dangerous work. So, shortages of skilled

operator have become serious problem. As solution

of these problems, in this study, a training assist sys-

tem for novice operator is proposed. The training us-

ing real machine has the risk of serious accident. In

addition, acquisition of safety and quick transporta-

tion technique is required a certain level of experi-

ence. So, safety environment for operation training

required. As alternative method of training using

real crane, crane simulators have been actively devel-

oped(Jiung Yao Huang, 2003)(Mohammed F.Daqaq,

2003). If you use these simulators, you can safely

and easily train without accident by the operating mis-

take. Currently, various realistic crane simulators that

are reappeared real work environment have been de-

veloped(R.Ito, 2009)(K.Watanuki, 2007). However,

many simulator cannot contribute to reduction of the

training time, because try and error exercise are re-

quired. In this study, the training assist system that

applies a human sense is developed. The purpose of

our study is development of the simulator such that

novice operator can efﬁciently master complex oper-

ation technique of the shipboard rotary crane. And we

discuss construction of better control system.

2 THE SYSTEM CONSTRUCTION

This system is comprised of shipboard rotary crane

training simulator and operating interface. Proposed

shipboard crane simulator is used existing graphics li-

brary (OpenGL) of highly-portable. Active-joystick

is employed as operating interface. Trainees operate

shipboard crane on the simulator while seeing display

433

Matsuda Y., Fushimi S. and Terashima K..

Development of Training Simulator for Sway Suppression Skills on Shipboard Rotary Cranes.

DOI: 10.5220/0005008104330440

In Proceedings of the 11th International Conference on Informatics in Control, Automation and Robotics (ICINCO-2014), pages 433-440

ISBN: 978-989-758-039-0

 2014 SCITEPRESS (Science and Technology Publications, Lda.)

monitor and using active joystick.

2.1 Graphics Library

3D graphics library of the simulator is using OpenGL.

OpenGL have functions such as 3D display, control of

the colors or pattern, geometric transform and shading

compensation. So, OpenGL is a simple graphics free

software. In addition, OpenGL can develop a system

without dependence for operating system.

2.2 Interface for Operation - Active

Joystick

Operating interface employs active-joystick devel-

oped in our laboratory (Fig.1). This active-joystick

has 6-axis force sensor, and X and Y-axis AC servo

motor. Firstly, force sensor feels operator’s force.

Second, AC servo motor is driven depending on oper-

ator’s force. AC servo motor realizes smooth motion

of the active-joystick, because of the compliance con-

trol.

AC servomotor

(Boom-hoistingref erence)

AC servomotor

(Rotaryreference)

Force/Torque sensor

AC sevomoter

(Rotary reference)

AC sevomoter

(Boom-hoisting reference)

Force / Torque

sensor

Figure 1: Experimental equipment of active joystick.

3 SHIPBOARD ROTARY CRANE

MODEL

In this study, shipboard rotary crane model is con-

structed of both the rotary crane model and a brief

ship model.

3.1 Rotary Crane Model

Schematic diagram of the target rotary crane is shown

in Fig. 2 and its parameter is shown in Table 1. In or-

der to simplify the system, the following assumption

is summarized:

• A crane is a rigid body.

• The load is a mass point.

• The rope’s weight, deﬂection and elasticity are ig-

nored.

• The friction and backlash for the power transmis-

sion device are inored.

Boom

Rope

Load

Dram Boom

Dram Rope

z)y,(x,

(

Figure 2: Schematic diagram of rotary crane for a load po-

sition model.

Table 1: Parameter of a load position model.

Symbol Unit Appellation

θ rad rotary angle

φ rad boom angle

l m length of the rope

m length of the boom

H m height of the turn table

kg mass of the suspended load

kg mass of the boom

kg mass of the ship

g m/s

gravity

F N tension of the rope

m/s wind velocity

α rad swing angle on the horizontal surface

β rad swing angle from the vertical direction

α rad swing angle on the X-axis direction

β rad swing angle on the Y-axis direction

( ˜x, ˜y, ˜z) m position of the crane tip

(x,y,z) m position of the load

) m/s wind velocity of each axis direction

The motion of a rotary crane is different from the

linear motion of an overhead crane or a gantry crane.

In the case of a rotary crane, the motion of the load

has an arc-like trajectory, and considering the effect

of centrifugal force, it is necessary to model the load

sway as a circular cone pendulum. A diagrammatic

illustration of a rotary crane is shown in Fig 2. In

addition, the system is simpliﬁed by the following

assumption. By seeing Fig.2, the boom tip position

in the crane coordinate ( ˜x

′

, ˜y

′

, ˜z

′

) is calculated using

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434

Eqs.(1)-(3) as follows:

˜x

′

= L

cosφcosθ (1)

˜y

′

= L

cosφsinθ (2)

˜z

′

= H + L

sinφ (3)

Coordination transformation from Σ

′

to Σ is done us-

ing Eq.(4).

X = T

xyz

′

(4)

xyz

X + T

xyz

′

(5)

xyz

′

+ 2

xyz

′

+ T

xyz

′

(6)

,where

′

and T

xyz

are as follows:

X = [

˜x ˜y ˜z 1

]

′

= [

˜x

′

˜y

′

˜z

′

]

xyz







− S

+ S

−C

−S

−D

0 0 0 1







= cosρ

, S

= sinρ

, (i = x,y,z).

The load position (x, y, z) in the coordinate Σ is calcu-

lated by using sway angle (α,β), boom tip position in

the Σ ( ˜x, ˜y, ˜z) and Eq. (7).

x = ˜x + l sin

βcos(θ+

α) (7)

y = ˜y+ l sin

βsin(θ+

α) (8)

z = ˜z− l cos

β (9)

The dynamics of the rotary crane is calculated by us-

ing lope’s tension F and Eqs. (11)-(12).

m¨x = −F sin

βcos(θ+

α) (10)

m¨y = −F sin

βsin(θ +

α) (11)

m¨z = F cos

β− mg (12)

3.2 Brief Ship Model

A brief ship model is easily built as 2nd order trans-

fer function using Computational Fluid Dynamics

(CFD), Flow-3D. The derivation process of the brief

ship model is shown in literature(N.Yong Jian, 2011).

When ship sway angle ρ

is output and torque added

to ship T

is input, transfer function G

ρx

(s) and G

ρy

(s)

can be respecting presented as follows:

(s) =

+ 2ζ

s+ ω

(13)

(s) =

+ 2ζ

s+ ω

(14)

Now, damping ratio ζ

, natural frequency ω

, and

gain K

must be identiﬁed (i = x,y). Conventionally,

these parameters must be identiﬁed by experiments,

but in this research, parameters can be identiﬁed by

computer simulation using a virtual plant comprised

of CFD model (Flow 3D) and rotary crane model.

This is a large advantage in this research. Concretely,

while transfer of rotary crane is executed using a vir-

tual plant, inclination angle of shipboard is calculated.

Parameter identiﬁcation is carried out by Least Square

Method using Simplex Method such that inclination

angle of shipboard by brief model matches with that

of a virtual plant. The parameter values obtained by

this method are as follows:

Table 2: Parameters of the shipboard crane.

Symbol Appellation Value

Mass of the load 17000 [kg]

Length of the boom 37 [m]

Height of the turn table 3.0 [m]

l Length of the rope 30 [m]

Mass of the ship 1500000 [kg]

Length of the shipboard 52 [m]

Width of the shipboard 19 [m]

Height of the shipboard 3.3 [m]

Distance from center of 20 [m]

the ship to the crane

= 2.177× 10

−9

, ζ

= 0.0677, ω

= 2.597

= 2.364× 10

−10

, ζ

= 0.0764, ω

= 1.964

Furthermore, sway angle is resolved x, y component

and these are added to the boom tip position of the

rotary crane model. In this way, the shipboard crane

model is obtained.

3.3 Simulation

For the validation of the shipboard rotary crane

model, its behavior was compared with virtual plant

using Flow-3D. Parameters of the shipboard rotary

crane are shown in Table 2. Transform pattern is

shown in Table 3.

Table 3: Rotary transfer pattern using simple mathematical

model.

Slew velocity Initial slew angle Target slew angle

[rad/s] [rad] [rad]

Pattern 1 0.05 π π/2

Figure. 3 shows the transportation trajectory of

the suspended load of the constructed model and the

virtual plant. By these results, reproducibility for

using training simulator was well achieved and this

model was employed for training simulator.

DevelopmentofTrainingSimulatorforSwaySuppressionSkillsonShipboardRotaryCranes

435

Figure 3: Comparison between Virtual plant and training

simulator.

4 CONTROL INPUT

In this section, sway suppression input for teach-

ing to operator is explained. The characteristics

of optimal input for teaching operator are shown

as follows(T.Iwasa and Y.Noda, 2010),(A.Tsutsui,

1998),(M.Kurimoto, 2009):

• Operation method can master as a formal knowl-

edge.

• Operator can estimate operating timing or operat-

ing quantity from motion of a crane or suspended

load.

• Operating method is simple.

Formal knowledge is technique or knowledge such as

anyone can deduce to only one answer from some

rule. On the other hand, implicit knowledge is tech-

nique or knowledge which must rely on so-called

”hunch” or ”experience”, and this knowledge com-

plicates acquirement of crane operation. So, implicit

knowledge must be removed from training system. In

this paper, a preshaping method and a Straight Trans-

fer Transformation (STT) are proposed as operating

method satisfying these conditions.

4.1 Preshaping Method

Preshaping method(N.Yong Jian, 2011)(T.Sasaki and

K.Terashima, 2013) is well-known vibration suppres-

sion method that input opposite signal for the ﬁrst in-

put signal. In Fig. 4, solid line shows response with-

out second input signal, while dotted line shows re-

sponse with second input signal. Dotted line is the

suppressed vibration by second input signal and ar-

rows show impulse input signal.

-0.075

0.075

0 10 20

Output

Time

without Control

with Preshaping Method

∆

1/(A+1)

A/(A+1)

Figure 4: Principle of preshaping method.

4.2 Straight Transfer Transformation

The present transfer using a rotary crane in actual sites

mainly uses rotary motion. However, because cen-

trifugal force is generated due to the rotary motion,

load is largely swayed, and it takes a long time to sup-

press the load’s sway. On the other hand, by using

simultaneous control of rotary and lufﬁng motion, a

Straight Transfer Transformation (STT) method (see

K. Terashima, et al.[2007] and Y. Shen et al.[2004])

where a load is carried out straightly on X-Y plane

from a start point to end was proposed. By using

this transfer method, load’s sway is restricted in the

straight direction only which is the transfer direction.

Thus, design of an anti-sway control for transfer is

made easier. In this paper, the STT method is adopted.

The control velocity reference for STT is calculated

along the straight transfer from start to end. Then,

its reference on straight line is respectively decom-

posed to each velocity reference of X-axis direction

and Y-axis direction. Furthermore, using Jacobi Ma-

trix which is derived from the relation between tip po-

sition of boom, and rotary and lufﬁng angle of crane,

each velocity is transformed into rotary velocity and

lufﬁngvelocity of rotary crane, which ﬁnally becomes

the control input of the rotary crane. The detail is de-

scribed in the literature (see Y. Shen et al.[2003] , K.

Terashima, et al.[2007] and Y. Shen et al.[2004]).

4.3 Transport Simulation

For the validation of controlled performance, we have

done transportation simulation. Control aim is to con-

verge within 0.3 m sway. Transportation trajectory,

velocity reference, rotary and lufﬁng velocity input,

residual sway and ship sway are shown in Fig. 6. By

seeing transportation trajectory, you know that sus-

pended load is rectilinear transported and sway of sus-

pended load is suppressed within amplitude of 0.3 m

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at the target position. By the result, it is clean that

control is well successful.

Figure 5: Concept of Straight Transfer Transformation

(STT).

Figure 6: Simulation result of STT with preshaping.

5 TEACHING TYPE TRAINING

SYSTEM BY INFORMATION

GUIDANCE

In this section, teaching method of sway suppression

proposed in last section is presented. In particular, we

have developed simulator as target that is an efﬁcient

teaching for implicit knowledge.

5.1 Visual Information Teaching

In this section, a training system that converts control

input information to visual information and teaches it,

is proposed(Attir, 2006)(M.Radjaipour, 2005). This

system uses simulator display. We have paid attention

to the position of the joystick, and operating position

of the joystick is shown as a ﬁlled circle on the simula-

tor display (Fig. 7). In addition, a cross cursor shows

ideal position trajectory of the joystick. A horizontal

axis shows rotary angular velocity input and vertical

axis shows the boom lufﬁng angular velocity. Con-

sidering the state of the load swing and rope motion

leads in the ﬁeld of view, the visual guidance infor-

mation was arranged near the suspended load. Oper-

ator operates the joystick as tracking a ﬁlled circle to

a cross cursor. So, operator can easily replicate the

sway suppressing input.

Figure 7: Visual guidance training system.

The ﬂow of this system is shown in Fig. 8. Block

diagram of the joystick maneuvered by operator is

shown the above diagram in Fig. 8. Diagram of the

joystick controlled is shown in the below side. Firstly,

the velocity input signal that is given by maneuver-

ing of operator is converted to angle information for

joystick. Next, angle information for joystick is con-

verted to visual information and it is outputted on the

simulator display. Indicating operation of the sway

suppressing, the information is outputted as joystick

that is maneuvered by operator. By outputting the

both simultaneously, training system by visual teach-

ing is built.

5.2 Haptic Information Teaching

In this part, haptic information teaching system using

active joystick is proposed. If operating angle of the

joystick deviates from ideal angle over certain angle,

active joystick feeds back force of correct angle to op-

DevelopmentofTrainingSimulatorforSwaySuppressionSkillsonShipboardRotaryCranes

437

Figure 8: Block diagrams of visual teaching system.

erator’s hand (Fig. 9). Operator can spontaneously

train, when operated joystick receive force.

The ﬂow of this system is shown in Fig. 10.

Firstly, sway suppression input that is obtained in ad-

vance and velocity input signal of the joystick that is

maneuvered by operator are compared. The force is

returned to operator by depending on the result of the

comparison. If needed, joystick angle is outputted and

force information is fed back to the joystick.

Figure 9: Active joystick motion of haptic teaching system.

Figure 10: Block diagram of haptic teaching system.

6 SIMULATION EXPERIMENTS

OF TRAINING

In this section, experiments for validity veriﬁcation of

the training system are presented. In the experiments,

it conducted that transportation test in condition with-

out any teaching after training by the simulator.

6.1 Method of Experiment and

Evaluation

Simulation experiments were conducted for human

subjects of the following three groups. In addition,

human subjects were selected such as that initial op-

erating skill is almost equal condition.

• Group A (n = 3): Self training

• Group B (n = 3): Visual information teaching

• Group C (n = 3): Haptic information teaching

Here, parameter n is the number of human subject.

Firstly, transport test without teaching is conducted 3

times. Next, transport test is conducted 3 times after

3 times trainings and these are conﬁgured as 1 set.

Moreover, 1 set is conducted. Total 9 times trans-

port tests and 6 times trainings were conducted. Crane

speciﬁcations in the simulation are shown in Table 4.

Experimental content is transport to the target posi-

tion within 1.0 m with sway suppression. Considering

result of STT simulation (in section 4.3) and human

operating, and transport time in set to 35.0 sec. Eval-

uation items set as the absolute value of the residual

sway within allowable target position.

Table 4: Parameters of a crane for training use.

Parameter Symbol Value Units

Rope length l 30.0 m

Boom length L

37.0 m

Initial slew angle θ π rad

Initial Boom angle φ π/3 rad

Slew velocity input

θ 0.00.1 rad/s

Boom velocity input

φ 0.00.1 rad/s

Initial load position X,Y 1.5, 0.0 m

Target position X,Y 20.01.0, 18.51.0 m

6.2 Experimental Result

The mean of residual sway of each human subject is

shown in Fig. 11. Furthermore, result of subject (1)

of Group A in the 3rd set is shown in Fig. 12, result

of subject (4) of Group B in the 3rd set is shown in

Fig. 13 and result of subject (7) of Group C in the

3rd set is shown in Fig. 14. Residual sway of Group

A shows the increasing tendency or the decreasing

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438

tendency. Self training doesn’t make constant train-

ing effect, because results of residual sway were var-

ied. On the other hand, all results of residual sway of

Group B and C are the decreasing tendency. Train-

ing effect is advanced by teaching system, and proﬁ-

ciency of operating skill is notably appeared. In par-

ticular, haptic teaching system is the highest training

effect, because the mean of reduction rate of residual

sway is 70% in Group C. The reason is that operator is

sensuously able to acquire the operation of joystick by

active training, because both visual and haptic sense

are used in Group C.

(a) Group A

(b) Group B

Figure 11: Training result of transfer process.

Figure 12: Training result of subject(1) in Group A.

Figure 13: Training result of subject(4) in Group B.

7 CONCLUSIONS

In this study, we built a virtual simulator to train sway

suppression skill in shipboard rotary crane. The re-

sults are as follows.

1. Movement of suspended load was reproduced by

3D model of shipboard rotary crane based on the

mathematical model.

2. Shipboard rotary crane was built by active joy-

DevelopmentofTrainingSimulatorforSwaySuppressionSkillsonShipboardRotaryCranes

439

Figure 14: Training result of subject(7) in Group C.

stick for the operation interface and 3D simulator.

3. Sway suppression control was adopted by pre-

shaping method, because control calculation is

simple.

4. Training system for teaching the operator was pro-

posed. The system presents operator both visual

information and haptic force for sway suppres-

sion.

5. Effectiveness of the training system was veriﬁed

by the results of training experiments using the

simulator.

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