ICCHP 2012

GPS AND INERTIAL

MEASUREMENT UNIT AS

A NAVIGATION SYSTEM

FOR THE VISUALLY

IMPAIREDAuthors:

Jesus ZEGARRA

René FARCY

Laboratory Aimé Cotton (France)

-To develop a device which can give to the visually

impaired the possibility to navigate to new places

in the cities; as a consequence, give a better

quality of life.

- To provide the instantaneous direction of the

blind person even if stopped

-To compensate GPS echoes and magnetic field

perturbations in urban areas

- Show the advantages and limitations of the whole

system relatively to standard GPS devices.

OBJECTIVES

GPS signal deficiencies (SIRF 3 - last generation): do

not give a right heading when they are in the cities

(hard reception conditions).

PROBLEMS

urban environmentReal way

Antenne GPS SIRF 3

GPS Smart Phone

Samsung OMNIA

GPS SIRF 3

The GPS devices do not give the right heading when the user does not move ( It is necessary a minimum of speed for updating the heading)

15 Km/h in average for having a right heading

Basic solution : the use of one IMU for giving the right heading in magnetic field perturbation conditions.

Objective: To update a correct heading every second for a speed less than 15km/h.

PROBLEMS

The unit system is :

- meters for the distances

- time dial for the directions i.e. : from 1 o’clock to 12 o’clock

with one hour of precision

for instance, “12 o’clock, 40 meters” means go straight, 40

meters, “9 o’clock, 90 meters” means turning left and walk 90

meters

HOW TO GIVE THE VOCAL INFORMATION

TO THE NEXT POINT?

For improving the information

-We have done extra information about the next point « Way to»:

-For instance:

<<Way to 2 hours>>, means that the next point n+1 turn to the right taking into consideration the orientation of the person

-

-

INFORMATION TO THE NEXT POINT

Use of an IMU (Inertial Measurement Unit),

developed in the laboratory containing : a 3 axis

accelerometer, a 1 axis gyroscope, a 3 axis compass

and a module Bluetooth transmitter to merge

information with the GPS. The device is placed on

the right side of the person.

SOLUTION

IMUGPS

MAIN DESIGN

3 axis

compass

sensor

1 axis

gyroscope

3 axis

accelerometer

sensor

Filter

Filter

Filter dsPic

Tx

ModuleBluetooth

SmartPhone

Rx-Bluetooth

GPS

Internet

There are three ways of saving the GPS coordinates(latitude and longitude) of the destination point .

Saving using the GPS antenna –used in the Navigation Window

Saving the coordinates by writing

the adress of the destination

Saving the coordinates by writing

directly the coordinates GPS

Keyboard 12 bottons

Window

HOW TO USE THE DEVICE?

NAVIGATION WINDOW-BRAILLE SYSTEM

Chosing the point

of destinationBoutton for saving

the current

coordinates GPS

Close the

Navigation

window

The user can chose the

points around him

between 2km, 5 km

and all the points

closer to him

Information about

the current adress

Heading and

distance to the

point of

destination

POIINTS

Heading

(°)

Cartograp

hique

Heading

(IMU)

Heading (°)

GPS 3,6

km/h

P1 291 280 330

P2 56 65 43

P3 109 110 100

P4 21 25 0

P5 50 55 25

P6 27 30 55

P7 32 30 25

P8 108 100 140

Average Error 5,375° 21,75°

Max Error 11° 39°

TEST TECHNIQUE (IMPROVEMENT OF

HEADING)

-The tests were conducted in Paris in the thirteenth, fourteenth and tenth neighborhood in bad GPS reception conditions : high buildings in small streets and bad magnetic conditions : walking along the Senna river (electrical cables), crossing metallic bridges, etc.

-Six points of destination were chosen (the distance between the destination can vary from 3 to 5 km). Ten visually impaired people tested the system (in category 3, 4 and 5 according to the World Heath Organization) .-

TESTS ABOUT THE USE OF THE WHOLE

SYSTEM

All the subjects arrived to the destination points

alone (except one who was not confident enough

after training to make the tests).

The benefits about the use of GPS seem to be

proportional to the initial autonomy of the visually

impaired.

Teaching the way of using the device is faster for the

subjects in category 3 than for those in category 4

and 5.

The main problem is keeping the security for the user

that suddenly increased his autonomy in unknown

environments. The risk was the same for the three

categories.

RESULTS

The GPS system coupled to IMU is better because the heading is more stable in the pedestrian navigation and, the person does not have to walk for knowing the direction to go.

The information about heading and distance is important because it lends us to arrive to the final destination with only the coordinates GPS of the final destination . It also works even when the cartography of the place is not well elaborated because the person can take any direction and the system can guide him until the destination . It seems to be one reliable guiding system option for the blind people in the cities.

Good autonomy of the whole system (6 hours enough for arriving one destination of 7 km)

CONCLUSIONS

THANK YOU FOR YOUR

ATTENTION