Emanuel Oliveira, Vítor Santos * Centre for Mechanical Technology and Automation

Emanuel Oliveira, Vítor Santos *Centre for Mechanical Technology and AutomationDept. Mechanical Engineering - University of Aveiro

3810-193 AveiroPortugal

Fibre Optics Gyroscope Evaluation and Calibrationwith a Mobile Robot

* E-mail: {eamaral, vsantos}@mec.ua.pt

SIRS2000

Contents:

1. Introduction

2. Gyroscope specifications

3. Drift rate compensation

4. Orientation error correction

5. Results

6. Gyroscope and odometers performance on irregular floor

7. Conclusions

Fibre Optics Gyroscope Evaluation and Calibration with a Mobile Robot

Dept. of Mechanical Engineering - Aveiro University SIRS2000

What is a Laser Gyroscope?

1. Introduction




5. Results

6. Gyroscope/odometers performance

7. Conclusions


Dept. of Mechanical Engineering - Aveiro University

A device that measures angular rotation by using internal generated, counter-propagating, optical beams.

Sagnac effect

c

LD2

for Open-loop fibre optic interferometers

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Gyroscope applications

1. Introduction




5. Results


7. Conclusions



Avionics

Naval

Land vehicles

Mobile robots

Underwater

NavigationIndustry

Automotive

industry

Generalindustry

Steering gearCar navigationBreaking system

Tilt sensing

Mobile robots

Platform stabilizationMotion sensing

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1. Introduction




5. Results


7. Conclusions



Mobile robots

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Gyroscope in mobile robotsGyroscope in mobile robots

1. Introduction




5. Results


7. Conclusions



When used in dead-reckoning, it can:

- increase accuracy in short-term information;

- reduce the requirements in absolute position updates.

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Autogyro from KVH IndustriesMain specifications

1. Introduction




5. Results


7. Conclusions



Power supply 12 V

Power consuption 3 W

Output16 bits, RS-232, 9600 bps, 10 values/sec

Rotation rate (max) ±100 º/sec

Drif rate (compensated)

5-10 º/h

Angle random walk (noise)

20 º/hr/Öh

< 0.5% rms (constant temp.) < 1% (full temp.)

Scale factor linearity

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Drift rate definition:1. Introduction




5. Results


7. Conclusions

Output signal when the gyroscopeis not rotating around its sensitive axis.



Drift rate definition:1. Introduction




5. Results


7. Conclusions




Random and systematic components

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Drift rate definition:

1. Introduction




5. Results


7. Conclusions





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1. Introduction




5. Results


7. Conclusions



Drift rate definition:



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Drift rate compensation

100 samples

1. Introduction




5. Results


7. Conclusions



-0.126 º/s

Subtract to the subsequent gyroscope outputs

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Orientation variation measurement using ultrasonic

sensors1. Introduction




5. Results


7. Conclusions



max<1º

Measurement accuracy

d1(max)= d2(max)=5mm max<1º

d2

d1

D

D

dd 21arctan

Orientation variation measurement using ultrasonic

sensors1. Introduction




5. Results


7. Conclusions



Orientation error without any correction

1. Introduction




5. Results


7. Conclusions



Correction factor calculation

1. Introduction




5. Results


7. Conclusions



where(t,) - rotation rate at the instant t and temperature

() - correction factor at temperature

If temperature is constant for all integration period†

†In practice the temperature varied less than 0.5 ºC in a 20 sec test.

T

real dtt0

)(),(

T

real dtt0

),()( T

real dtt0

),()(

measured

realT

real

dtt

0 )(

)(

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Correction factor calculation

1. Introduction




5. Results


7. Conclusions



CWCCW

Using least square method...

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Results after calibration

1. Introduction




5. Results


7. Conclusions



CW

CCW

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1. Introduction




5. Results


7. Conclusions



Before After

Improvement of ca. 60% in absolute orientation accuracy

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Gyroscope and odometer performanceon irregular floor

1. Introduction




5. Results


7. Conclusions



Gyroscope

Odometers

Real

Gyroscope and odometer performanceon irregular floor

1. Introduction




5. Results


7. Conclusions



Conclusions

1. Introduction




5. Results


7. Conclusions



• Temperature correction is very important in orientation errors compensation;

• Gyroscope is an essential sensor for outdoors environment navigation.

– Using linear correction factor it lead to 60% improvement in orientation accuracy

– Non linear correction factor or piecewise linear fitting can improve results for a higher temperature range.

– Gyroscope was immune to bumps and wheel slippage (the most relevant errors in odometry).

SIRS2000

Emanuel Oliveira, Vítor Santos *Centre for Mechanical Technology and AutomationDept. Mechanical Engineering - University of Aveiro

3810-193 AveiroPortugal

Fibre Optics Gyroscope Evaluation and Calibrationwith a Mobile Robot

* E-mail: {eamaral, vsantos}@mec.ua.pt

Emanuel Oliveira, Vítor Santos * Centre for Mechanical Technology and Automation

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