An Embedded Linux Based Navigation

System for an Autonomous Underwater

Vehicle

Presented By:

Priyanka Katkar

Under the Guidance of

Mr. B.G. Patil

1

Outline

Introduction

Interfacing With SBC

System Architecture

Hardware Development

Software Development

Conclusion and Future Work

2

Introduction

• AUVs are unmanned and untethered submarine vehicles, used to

gather ocean data.

• Find applications in the area of mines clearing operation, feature

tracking, cable or pipeline tracking and deep ocean exploration.

• HUGlN 3000 was the world's first AUV used in commercial survey

operations.

3

Use of the AUV

• Search and Recovery of Government Property.

• Prediction of Waves and Currents.

• Readings for depth, salinity, pressure and temperature.

• Pictures of visual light, bioluminescence.

• Discovery of never seen before species and footage.

4

UUV Research

5

6

Nomenclature

• Unmanned Underwater Vehicle (UUV): Self propelledunmanned submersible

• Remotely Operated Vehicle (ROV): controlled andpowered from the surface by an operator/pilot via anumbilical or using remote control

• Autonomous Undersea Vehicle (AUV): Un-tetheredUUV operating with no or very limited operator control.

• Two paddle wheel thrusters are installed on AUV, one forhorizontal motion and other for vertical motion

7

Navigation Techniques

• AUV: The benefits of offered by autonomous data gathering

• Examples include the Theseus AUV, developed by Interna-

tional Submarine Engineering, the DARPA UUVs, developed

by Draper Laboratories, the LDUUV and 21UUV developed

by the Naval Undersea Warfare Centre in Newport.

• The three primary methods for navigation of AUVs are:

1. Inertial navigation systems

2. Acoustic navigation

3. Geophysical navigation techniques.

8

System Architecture

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INS KF

DGPS +USBL UTP

Pressure

Sensor

Compass

DVL

Bottom-Track

Velocity

Altitude

Depth

Smoothing

Position

Error

estimates

Inertial Measurement Unit

10

Outline of Conventional Aided INS

11

The Complete System Setup

12

Interfacing With SBC

• Single Board Computers (SBC) like Kontron E2Brain

EB8540, Gumstix, Inhand Fingertip- Elf, AMD GX SOM-144

and TS-7200

• TS-7200 SBC selected due to its features, good support by the

manufacturer and a huge user community. TS-7200 is based on

200MHz Strong ARM processor.

13

TS-7200 Hardware

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The CirrusLogic EP9302 and TS-7200

• The EP9302 features an advanced ARM920T processor design

with a memory management unit (MMU) .

• Supports Linux & many other operating systems.

• Contains 16Kbyte instruction cache and 16Kbyte data cache.

• supports both the 32-bit ARM and

16-bit Thumb instruction set.

• The core can operate in big

and little endian mode

15

(Cont...)

• The TS-7200 is a compact full-featured (SBC) based upon the Cirrus

EP9302 ARM9 CPU

• The TS-7200 SBC runs on a 200MHz EP9302 ARM9 processor with

power as low as 0.5Watts.

• includes a compact flash interface which allows booting from large

flash drives to the different Linux distros.

• fast boot from the on-board Strata Flash memory using a compact TS-

Linux distribution.

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Interfacing of INS with SBC

Block Diagram of Integrated Sensor Pack

17

Tracking Algorithm

Calculation of object

centroid in the image

Separation of moving

objects from the

stationary objects

Identification of moving

objects based on change

in centroid values

Comparison of centroid

values in all subsequent

frames

Calculation of trajectory

for all moving objects Calculation of speed and

direction of moving

objects

Block diagram of the complete model18

Kalman filter

• The Kalman Filter is an estimator for the linear-quadratic

problem, estimating the instantaneous ‘state’ of a linear

dynamic system perturbed by white noise.

• The Kalman filter is a set of mathematical equations that

provides an efficient computational (recursive) means to

estimate the state of a process, in a way that minimizes the

mean of the squared error.

• Various Kalman filter configurations applied to a low-cost

inertial navigation system (INS) for AUV.

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Kalman Filtering Algorithm Time Update ( Predict ) equations:

• Step 1: Project the state ahead:

𝑋𝑘− = A 𝑋𝑘−1 + 𝑊𝑘

• Step 2: Project the error covariance ahead:

𝑃𝑘= A 𝑃𝑘−1 𝐴𝑇+ Q

Measurement Update ( Correct ) equations:

• Step 3: Compute the Kalman gain:

𝐾𝑘 = 𝑃𝑘 𝐻𝑇(H 𝑃𝑘 𝐻𝑇 + R)−1

• Step 4: Update estimation with measurements:

𝑋𝑘= 𝑋𝑘− + 𝐾𝑘 (𝑍𝑘 - H 𝑋𝑘

− )

• Step 5: Update the error covariance:

𝑃𝑘 = (I - 𝐾𝑘 H) 𝑃𝑘−

• Step 6: Go to Step 1. 20

GPS Receiver

• To provide the absolute positioning of any object, GPS uses a

constellation of 24 satellites.

• Four satellites are visible at all times from any point on the earth’s

surface.

• GPS receiver supports NMEA 0183 data protocol.

21

Software Development

• TS-Linux embedded distribution is installed on the on-board Flash

memory of the TS-7200.

• TS-Linux is a compact distribution, which is based on Busy Box

• The GPS receiver is interfaced to the TS-7200 through the serial port

• Linux distinguishes devices into three fundamental device types: a

char module, a block module, or a network module.

• Developing a serial class is classified.

22

Results

Output from the ADC and the GPS Receiver.23

Future Scope

• The exact position of the vehicle can be determined by

processing the logged sensor data using the Kalman filter.

• Current version does not have a driver for the digital I/O port.

• This can be implemented to increase the no of sensors that

can be interfaced with SBC.

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Applications

• Pipeline inspection and intervention.

• Under ice surveys (transponders may be deployed from

an ice breaker or along the ice ridge).

• Mines clearing operation, feature tracking, cable or pipeline

tracking and deep ocean exploration.

• Autonomous surveys where surfacing or support from a

surface ship are infeasible due to e.g. heave traffic.

25

Pros And Cons

Pros

• Smaller, Lighter and less expensive equipment became

available, the access to operational vehicles which made more

affordable AUVs.

• TS7200 has on board Apaches web server therefore data logged

from SBC can be displayed on a web page.

Cons

• Limited number of DIO ports available on SBC board.

• loss of controllability at low speeds, 26

Conclusion

• The SBC with Linux setup and the development tools form the

embedded Linux development system.

• Provides lower development cost with interfaces such as Ethernet and

USB and have made AUVs more affordable.

• As a data logger/analyzer of various sensor measurements for Marine

research.

27

References

• Grenon, G., Edgar, P., Smith, S., and Healey, A., “Enhancement of the inertialnavigation System for the Morpheus Autonomous underwater Vehicles”,IEEE Journal of Oceanic Engineering, Vol. 26, No. 4, October, 2012.

• Yun, X.; McGhee, R.; Whalen, R.; Roberts, R; Healey, A, and Zyda, M.,“Testing and Evaluation of an Integrated GPS/INS System for Small AUVNavigation” IEEE Journal of Oceanic Engineering, Vol. 24, Issue 3, pp.396–404, 19-20 July, 2007.

• B. Jalving, K. Vestgkd, N. Sterkersen, “Detailed seabed surveys with AUVs” in TechnologV and Apphcurions of Autonomous Underwater Vehicles. Edited by Gwyn Grifiths. Tavlor & Francis. London and New York. 2008. pp. 179-201

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Thank You

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