3D tools for the Robust Design Optimization of an

3D tools for the Robust Design Optimization of an Autonomous Underwater Vehicle

Andrey Kirsanov*, Sreenatha G. Anavatti and Tapabrata Ray School of Engineering and Information Technology University of New South Wales Canberra, ACT 2600, Australia *Email: z3397566@student. adfa. edu. au

Abstract

This

development Design

of

the

describes

methodology

Optimization

Autonomous

paper

based

on

for

3D

Robust

tools

for The

Vehicles.

Underwater

the

specifications for the design are picked up from

design for variations around this. Nowadays, global industry companies align their production through approaches based on the minimum economic losses. One of the most effective methods is using RDO. This

method allows faster

design

creating the

the Scope Statement incorporating the mission

effective

requirements,

unmanned vehicle to suit the mission requirements.

including

the

guidance

navigation specifications.

The

incorporates

of

and

model for guidance and navigation of

methodology to

Today, 3D graphics is widely used during the

achieve the mission, the links, both internal and

build process. This paper uses this 3D technology

the

D atabase

components

external to provide a clash-free arrangement of

with

the components. Polygon Optimization is utilised

Underwater

the

RDO

for

for internal arrangement. Numerical results are

design process come from the mission requirements

presented for an actual case.

or the guidance and control requirements.

Keywords - Autonomous Underwater Vehicle; robust design optimization; bounding boxes; 3D optimization

based on the mission requirements by creating a

Vehicles.

designing The

Autonomous

specifications

for

the The

components that make up the AUV are selected Database of the available components. Assembly of complex systems and structures in I. The system

INTRODUCTION

development for

of

3D was proposed by Siemens Company as a part of

guidance

Autonomous

and

Underwater

(AUVs) is a challenging task.

control

Vehicles

This is due to the

non-linear dynamics of the AUVs coupled with uncertainty in operating conditions leading to time­ varying dynamics. One of the possible ways to get the

optimal

performance

from

guidance

and

navigation system is to design the vehicle with these specifications. Due to the changes in the operating conditions and the variations of the payloads, the solution may not be optimal for all the conditions. To

overcome this,

(RDO) is introduced.

Product Lifecycle Management (PLM) in early two thousand years [1]. Later, this technology has been supported by many other companies such as: Boeing, Dassault, etc [2].

The main disadvantage of this

approach is the lack of a mechanism that allows changing or adding the elements to the Database in build process.

The current

work

proposes

a

solution to this problem. The method is to create a phase-splitting process during the 3D assembly and flexible links between components in Database. This is used in the current paper.

Robust Design Optimization This

leads

to

optimal

condition for a particular case and nearly optimal

978-1-4673-6217-7/13/$31.00 ©2013 IEEE

The components need to be placed suitably to provide clash-free environment. This is achieved by

1730

using

Polygon

Optimization

during

the

clash-free placement of the components to achieve the required centre of gravity and buoyancy point locations.

THE DESIGN PHOLOSOPHY

II.

design

phase. Thus, the methodology provides an internal

The fIrst part of this design method is the Scope statement. The Scope statement includes the whole process

of

project

organization

from

input

parameters of the AUV to the approximation of the

Section 2 provides the overall methodology of

cost of a program, project, or operation (Figure 1).

the RDO process. The selection of the D atabase is

This includes the specifIcations from

discussed in Section 3. Section 4 provides the links

point

between the different components.

requirements. We must create an algorithm which

The process of

of

view,

like

navigation

the mission

and

guidance

Polygon

can read the input parameters, work with Database,

Optimization is presented in Section 6 along with

create a component selection fIle, import objects

some concluding remarks in Section 7.

from another program tools, render the scene in a

assembly

is

discussed

in

Section

5.

real time, analyse the results of the project: � --------------------------

Input parameters:

Scope statement

Parameter 1

• Database of components

Parameter 2

0----

+

Parameter 3

Selection of components

+

Parameter N ---

------------------

Components optimization

---

+

--------------------------

Importing the AUV' s shape

Input components:

r---+

DC motor

from CATIA

+

Batteries

The assembly of components Board computer

in the 3D

+

Sensors ---

I

------------------

Generating the shape

Fig.

1:

Visual analysis of results

---

�

Robust Design Optimization, 3D assembly of components

The Database is collected from components, regardless of the fInal purpose of AUV but with

imports generated objects from CATIA to a real time 3D

engine

[3].

It' s

required

for

creating

and

some of restrictions, such as: dimensions, weight,

assembly

power consumption, etc. The Scope statement in

components, measuring grid, and other 3D objects

most cases is provided by the customer, and it

in Unity 3D Engine [4], [5].

depends on the area of work: industry, etc.

military,

science,

The next stage is the selection of

components from the Database.

If the necessary

component is missing in Database then it can be installed in the process. FBX format of 3D models

2013

the

3D

III.

scene

with

AUV' s

shape,

THE DATABASE

The Database created for the experiment with 50 different components can be used in robust

International Conference on Advances in Computing, Communications and Informatics (ICACCl)

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design optimization of the AUV [6]. All of these components have a wide number of parameters. The

full list of components is presented below: Table 1: The list of DC motors with planetary gear

Supply Rated tvoltage, orque, g'cm �

Model

IG16GM1 IG16GM2 RA20GM1 etc.

12 24 12

Rated speed, pm

5 9.7 22

dIe Power Radial �hrust Weight, urrent, p utput, play of play of � A �haft, shaft, W Plm P1m 0.01 100 0.39 50 0.09 l.03 0.01 100 50 0.09 0.1 l.5 0.02 150 50

Rated Idle current, speed, pm rnA

6270 10400 6700

85 90 200

8000 l3500 8000

Table 2: The list of Board computers

Model PCM-3343 PCM-3353 PCM-3355 etc.

CPU, MHz 800 500 366

RAM,

MB 256 1024 1024

SSD, GB 4 8 4

USB

COM

4 4 2

2 4 3

LAN, MB/sec 10 10 100

Power consumption, Watt 4.25 8.75 9.9

Table 3: The list of Batteries

Model

Type

DT12012 DT12022 DT12045 etc.

Pb Pb Pb

Voltage, V 12 12 12

Charge, A·h l.2 2.2 4.5

Size, mm

Weight, g

Volume, mmj

97x43x58 178x34x66 90x70x107

580 970 1600

241918 399432 674100

Table

Model

Resolution

KP-F33GV KP-F83GV KPF140GV etc.

656x494 1034x779 l392x1040

Pixel size, �m 7.4 4.65 4.65

FPS 90 36 30

Sensitivity, Ix 550 400 2000

All components listed above are designed for extreme environmental conditions, such as: deep underwater work, low temperature, chemical environment etc. IV. THE LINKS There are links between the parameters of components in these tables. These connections help

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4:

The list of Sensors

eight, 1P0wer consumption, Control "hannel lWatt g 140 4 RS232 200 4.5 USB 220 USB 5

to determine the most effective selection of components, depending on the terms of Scope statement. Number of connections is not fixed and can be added as needed. All values in the tables are normalized before optimization process. The main selection parameters include: size, weight, power, capacity. All connections of components are presented below (Fig. 2):

International Conference on Advances in Computing, Communications and Informatics (ICACCl)

- - ---- - -- - - - -- - ---- - -- - - - -- - ---- - -- - - - -- - - - -- - -- - - - -- - - - -- - -- - - - -- - - - -- - ---- - -- - - - -- - ---- - -- -

Internal Links

r------------I I I I I I I I I I I I

DC

\ I

Motor r-----------I Board computer I I

Supply voltage, V

RAM, MB

Rated speed, rpm

SSD, GB

Rated current� rnA

USB

Idle speed, rpm

Idle current, rnA

COM

Power Output, W

Radial play of shaft, mm

Thrust play of shaft, mm

----

I

CPU, MHz

Rated torque, lUffi

I I I I I I I I I I

LAN, MB/sec

Sensor

Power consumption,

Resolution

Watt

Charge,

Pixel size, ill!l

!Vl

FPS Weight, g

---- )

Sensitivity, Ix

Weight, g

Power consumption, Watt

Control channel

I

,

,-

-

------------------

-------- - ---- - -- - -_____ ,1

,

I

r----

I I I

-

Weight

'

--

,

I

I I

Speed

:

I

--

Vehicle

:

l ____________________________________________ �

,------- - ----------------- - ------------------------- - ------------ - ------------------------- - --,

Fig.

2:

Flowchart of connections between components

v. ASSEMBLY PROCESS When the selection process of the components of AUV is finished, it is required to import objects (shape, components, etc.) into the Unity 3D engine [7]. This will allow us to visualize the assembly process of the vehicle. The best option to import 3D objects is to use the FBX file extension [8]. The FBX file extension is widely used in all known 3D engines and tools from Autodesk [9], [10].

1.

the Database 2.

2013

Bounding box creation for all components

(e.g. Collision detection) 3.

Finding the centre of gravity in each

component 4.

Components integration into the shape of

AUV 5.

Weight distribution of objects in the shape

of vehicle

The assembly process of the vehicle consists of several stages:

Selection of the necessary components from

Finding the centre of gravity in the component can

be

calculated

automatically

or

International Conference on Advances in Computing, Communications and Informatics (ICACCl)

specified

1733

manually.

For

aeronaut"

is

example, a

the

complex

object

model

"Race

for

400

manually specify the centre of mass. However, the object "DTI207" is rather simple and its centre of can

be

specified

using

the

By·0. 5, Bz·0. 5) ; Ceenter (Cx·0. 5, C y·0. 5, Cz·0. 5) ;

automatic

calculation of centre of gravity, and we have to

mass

Aeenter (Ax·0. 5, Ay·0. 5, Az·0. 5) ; Beenter (Bx·0. 5,

where A, B, C are boundary points of each edge bounding box.

automatic

calculation based on the bounding box [11], [12].

o Fig. 4: Automatic definition of the centre of mass in

"DTI207" Fig. 3: Manual definition of the centre of mass in "Race

Also, we need to divide the shape of AUV into

400 aeronaut"

several logical parts: nose, middle body, tail. Each

Automatic calculation of centre of mass uses the principle of the "Sweep and prune" algorithm [13]. Coordinates of required points (vertices) [14] are determined by the following calculation:

part includes a specific set of components from a Database. This means that in addition to the internal links between parameters of components there are external links between components and parts of AUV. All external links are shown on the Fig. 5:

SENSORS,

BOARD COMPUTERS,

digital,

PCM class

analog

BATIERIES, DT, DTM class DC MOTORS,

Fig. 5: External links in 3D view of AUV

External links are created after internal links.

the purpose of the AUV, we have several options for

The main purpose of internal links is parameters'

the design. For commercial purpose, the AUV could

optimization between each of components of the

be designed with maximum number of batteries in

vehicle.

middle part and low-power DC motors in the tail of

The

main

purpose

of

external

links

is

distribution in the shape of vehicle. Depending on

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2013

body. For military purposes the AUV could be

International Conference on Advances in Computing, Communications and Informatics (ICACCl)

designed with power pumps and protected PC [15] unit for hazardous body.

For

environment in

middle part

of

research purpose the AUV could be

designed with high precision sensors and power P C unit, sensors must b e located i n the nose section of the body. Parameters such as size and weight are read from the Database and are optimized for the selected shape. VI.

POL YGON OPTIMIZATION

Fig. 6: The model of AUV with

1924 points

The obvious approaches to collision detection for

multiple objects are very slow

[16],

[17].

Checking every object against every other object will ...

work, but it is not efficient with a big number of objects. Checking objects

- .

"

.

.

-

. "

.

'

.

.

�

.

with complex geometry

against each other in the obvious way, by checking each face against each other face, is quite slow itself [18],

[19].

During the creation of

the

j

assembly

.'

process, we need to consider the speed of 3D models calculation for real time software [20]. The task is to

Fig. 7: The model of AUV with

decrease the number of points (vertices) in 3D model with minimal loss of quality

482 points

but at an acceptable

speed of data processing [21]. For this purpose we created three types of the same AUVs model but with different number of points:

Fig.

8:

The model of AUV with

241

points Q) E c: o

......

OJ ::I OJ

---

-�

---

--

----

-------J

----- -- ----,

"

Fig.

2013

9:

diagram of the nwnber of vertices, components, and time (ms)

International Conference on Advances in Computing, Communications and Informatics (ICACCl)

1735

Using the diagram (Fig. 9), we can see that the optimal solution for the calculation of the ratio of time to the number of objects and vertices. For this study, the constraints posed are; a) The minimum number of components in the vehicle is five: one DC motor for propeller, one battery, one PC unit and two pumps (yaw and pitch). b) There is a limit on the size of the vehicle - no more than fifty components could be placed there. As the assembly process is required in real time, we must reduce the calculation time to the minimum possible value - 2500ms or 4000ms. Using these time restrictions, the number of vertices in the shape of AUV must not exceed two hundred and forty-one. One of the intermediate stages in the design is displayed in Fig. 10.

VII.

CONCLUDING REMARKS

The paper presents a methodology for RDO of AUVs. The overall specifications for the design come from mission requirements. The novelty of this approach is to optimize the Database of components, rendering the assembly process, replacing or adding the necessary elements on-fly, integration of 3D models to the system and reading all their parameters. This software tool can be used for the calculation and optimization of any type of unmanned vehicle for internal clash-free design with known centre of gravity and buoyancy point. The future work looks at developing a robust controller based on the hydro-dynamic properties of the designed vehicle.

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Fig. 10: Program in the build process

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2013

International Conference on Advances in Computing, Communications and Informatics (ICACCl)

[15] G. Subrata, "8051 MicrocontroIIer: Internals,

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