Linearization of Non-Linear Pressure
Sensor for Autonomous Underwater
Vehicle
Presented By:
Dominic Besner, Martin Kmita, Mélanie Potvin
ELG 4135
Electronics III
Dr. Riadh Habash
Nov. 28, 2006
System Overview
Pressure
Sensor
Compass
SBC
D.V.L.
Sonar
Actuators
(Motors)
Focus of Project

Pressure Sensor
Pressure Range: 0 – 25 PSI
Input: 4.75 – 5.25 V DC
Output: 0.5 – 4.5 V DC
Objective

Expected Linear
Behavior:
P= Po+ ρgD

Actual Non-Linear
Behavior :
V = 0.0768 D2+0.01255 D +0.62
Possible Solutions

Table Look-Up
– Pros : Speed of the data analysis
– Cons : Not accurate

Frequency Domain Linearization
– Pros : Only need few inexpensive components
– Cons : Filters are not ideal

Mathematical Models
– Pros : Accuracy
– Cons : Need Mathematical Library
Pressure Sensor Diagram
Chosen Implementation
Chosen Equation
Sensor Equation:
V = αD2+βD+C0

α = 0.0768,
β = 0.01255,
C0 = 0.62
Desired Equation:
V’ = γD

Chosen Equation

Linearization Equation:
V = AV’2 + BV’ + C0
V’ = 1/A ( (V-C0)/V’ - B)
A = α / γ2
B=β/γ
γ = 0.2046 , A = 1.8355, B = 0.0614
Implementation
Circuit
Offset Compensator
Divider
Adder
Implemented Circuit
Simulation Results
Results
Conclusion



Modeled the non-linear characteristics of a
pressure sensor using a second order
equation
Designed a mathematical model to
linearize the output voltage
Implemented a linearization circuit using
simple and inexpensive components based
on the mathematical model
References





Christopher D. Williams, “AUV Systems at the NRC-IOT: An Update”, IEEE Underwater
Technology, 2004. UT '04. 2004 International Symposium on, 2004.
Nabil I. Khachab, Mohammed Ismail. “Linearization Techniques for nth-Order Sensor
Models in MOS VLSI Technology”. IEEE Transaction on Circuits and Systems, Vol. 38,
No. 12, Decembre 1991.
J.M. Dias Pereiral, O. Postolache, P. Silva Girao, “Adaptive Self-Calibration Algorithm
for Smart Sensors Linearization”. IMTC 2005 Instrumentation and Measurement
Technology Conference, Ottawa, Canada, May 17 to 19, 2005.
D. Besner, J. Cheong, E. Ho, M. Kmita, S. Nguyen, “Development of an Autonomous
Underwater Vehicle with Custom Passive Sonar”. University of Ottawa, December
2005.
Benson Harris, “University Physics”. John Wiley & Son Inc., revised edition, Quebec,
Canada, 1996, Chapter 14, p: 284-292.
References (con’t)




MSI sensor. “MSP 600 Datasheet”. May 25th 2004, Revision C.
TSI Incorporated. “Thermal Anemometry System”
http://www.tsi.com/TechNotes/technotes.aspx?Pid=197&lid=544&file=ta-lukuptbl.
Visited on November 5th, 2006.
Grayson King, Toru Fukushima. “RTD Interfacing and Linearization Using ADuC8xx
MicroConverter”. Application Note for Analog Devices, Rev. 0, 2004.
Kwok-Keung M. Cheng, Chi-Shuen Leung. “A Novel Generalized Low-Frequency SignalInjection Method for Multistage Amplifier Linearization”. IEEE Transaction on Microwave
Theory and Techniques, Vol 51, No.2, February 2003.
Thank You !
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