Design & Control of Autonomous Underwater Vehicle

SEA 1.0 Md. Abu Shahzer, Faraz Ahmad Khan, Ali Shazan Gulrez, Haris Siddiqui, Jatin Varshney

Faculty Advisor: Dr. Saleem Anwar Khan

Presented by

Ali Shazan Gulrez & Jatin Varshney

Team ZHCET, Aligarh Muslim University

Present Work- Objectives

• Design Autonomous Underwater Vehicle needed for ocean observation

• Keep its weight optimum for desired operation• Design AUV less than 2 m of length and 0.5 m of diameter• Design under water vehicle such that it can bear 5 m of

water pressure• Follow the assigned path, pick and drop objects from and to

the specific bins• Design a vehicle which is self sinking to a desired level

under water and self rising to the surface, using buoyancy• Device an automatic control for the vehicle to make it

autonomous

Design

• SEA 1.0 is designed positively buoyant• Water suction makes SEA neutrally and negatively buoyant

depending on amount of water entered inside• Upward-downward motion achieved by buoyancy control• Structure designed using CAD software • Center of mass lies below center of buoyancy along Zv axis

• Couple created on displacement in x-z plane will always be restoring

• Coordinates Cb (-13.24, 0) mm and coordinates Cg (-13.24, -389.743) mm

• Position of cg adjusted so that XCG is equal to XB (adjustment done by placing dead weight suitably)

• CD = a α2 + b α + c, where, a = 5.25 rad.−2, b = -0.315 rad.−1,

c = 0.732,

z

x

α

BL

Dw + Df

T

W

u∞

XV

ZV

cb

cg

Zgb

21

2

D

DC

u A

CD

α

Hull Drag, CD versus α, at u∞ = 0.5 m/sec

• Dimensional form of governing equations of underwater vehicle dynamics in x – z plane

• Internal structure– Four PVC plates of 200 mm diameter and10 mm thickness– Six 18mm diameter holes on each plate symmetrically drilled and aligned to allow six aluminum rods of 16mm

diameter to pass through– Two stretchable plastic water pipes of 50 mm diameter attached to bars moved horizontally by a single DC servo

motor placed at the centre of the structure which expand and contract the pipes for the buoyancy changing mechanism.

– Electrical components inside: 18.5 V rechargeable batteries , two D.C. servo motors, on-board computer and extra battery as dead weight

2

2

1x-momentum: [ sin cos ] cos

2

1z-momentum: [ cos sin ] sin

2

where, and L is characteristic length

L D

L D

uu uu w C C tx z L

uw wu w C C t gu z L

Tt

21z-Moment: Z ( )( cos sin ) sin

2gb L D

I Au C C T B

• External components– Main Pressure Hull: PVC material. – Front cap hollow with converging end, 300mm in length and 200mm in

diameter (front and rear portion for water suction)– Hydro-dynamically designed to reduce wave resistance and friction drag– Main delta wing with two more delta wing attached at extreme left and

right corners of the main pressure hull to provide stability– Two six strap-on BTD150 thrusters each mounted on the rear side of

the AUV– Thrusters provide power for forward movement as well as differential

control used for turning while in stationary position– Robotic arm of Aluminum for collecting and dropping objects attached– Navigation sensors (for sensing the motion of the vehicle), Mission

sensors (for sensing the operating environment and mission events), and Depth sensor.

– Two small CMOS-color camera

CAD Design of SEA

Partially Assembled model of SEA

Simulation of AUV

Simulation Parameters

• Atmospheric pressure = 1bar• Temperature = 30 deg C• depth of vehicle = 2 m •Depth of sea bed =15 m •Relative velocity = 0.5 m•Negligible viscosity •Designed in ansys design modeler and meshed in ICEM CFD. • modal:- ansys – fluent (inviscid – laminar).

Electrical System Design• Provide motion control

• Provide Image Processing

• Measure the vehicle’s depth

• Discern the vehicle’s attitude

• Measure the vehicle’s Surge velocity

• Provide Regulated Power to each Component

1.66GHz On board processor

Cam Front

CamBottom

Wi-Fi module

ActuatorBoard

Workstation PC

LV-EZ1

iNEMO board

Robotic Arm Control

Wireless Communication

MC33926 through servo

Thrusters

T1

T2

Servo Motor, Depth Control

I2C L298

M1

18.5 V 5000mAh

18.5 V 5000mAh

Distribution

Block Diagram of Electrical System Design

CONTROL SYSTEM DESIGN

Computed Torque Control

MV’+D(V)V+G=T ______________(i)we assume a Linear TorqueT=AT’+B_____________________(ii)T’ is chosen based on Position & VelocityT’=-KvV-KpP__________________(iii)V’+KvV+KpP=0________________(iv)Errors are defined as e=Pd-P; e’=Vd-V; e”=Vd’-V’_______(v)Implementing PID Control T’= ___(vi)T= _______(vii)

Kp

Kpi1/s

Vd’

Kvi

1/s

Kv

M SEAP

V

D(V)V + G

Vd

Pd+

++ +

+ +

+ T

-

+ +

+ -

e

e’

PID Tracking Controller Block Diagram

PID TRACKING CONTROL

S.NOName Of

Part

SpecificationEstimated

CostDiameter(mm)

Power(kW)

Voltage(V)

Length(mm)

Torque(N-m)

Weight(kg)

RPM MaterialNumberRequired

1.Main

Pressure Hull

204 - - 824 - - PVC 1

2.Front End

Cap210 - - 288 - - PVC 1

3.Rarer End

CapPVC 1

4. Delta Wing PVC 1

5. Propeller 19.1 SEA Botix 2 1,70,000

6.Robotic

ArmNex

Robotics1 12000

7. Plates Aluminium 4

8. Rods Aluminium 6

9. Processor Intel 1 25,000

10.DC Servo

Motor5 Fatuba 2 1000

11. Camera Microsoft 1 2000

12. Atmega 640 5 Atmel 1 2500

13.iNEMO module

5STM

Electronics1 3000

14. Battery 18.5 Li-Poly 2 7000

PLAN OF ACTION

•August 2012•Designing & Body FabricatingLevel 1

•January 2013•Control Design, Buoyancy ControlLevel 2•Summer 0f 2013• Completion of AUV•Financial Assistance from AMU, Alumni Associations, private and public sector Organizations

Level 3

CONCLUSION

• Proposed design weight approximately 22 kg• Dimensions of SEA 1.0 are well within required

specification• AUV design proposed can withstand 5 m water pressure• Control mechanism proposed is suitable for SEA 1.0 to

follow the assigned path, pick and drop objects from and to the specific bins

• Vehicle design proposed is self sinking to a desired level under water and self rising to the surface, using buoyancy control mechanism

• The cost is also optimized• Simple mechanism is used for control dynamics

Thanking You all