here (x) - SmartCampusAAU

pogonotomygobbleAI and Robotics

Nov 15, 2013 (3 years and 11 months ago)

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SmartCampusAAU

APP

-

Enabling

Ubiquitous

Positioning

and
Navigation
Through

Crowdsourcing

Motivation


GPS
positioning

and navigation has
become

commonplace
,
but GPS has
severe

problems
inside

buildings
:


GPS positions
estimates

are

very

coarse
.


There

is
no

semantic

information
, i.e., information
about

rooms
,
escalators
, printer
facilities
, etc.


There

is
no

indoor

navigation.


The
SmartCampusAAU

app

addresses

these

shortcomings

by
providing

indoor

positioning

based

on
user

contributions

and
Wi
-
Fi

technology
:


Positioning

accuracy

can

be

as
good

as
three

meters,
depending

on a
variety

of factors,
including

the
amount

of data
supplied

by
users
.


There

is
semantic

information (
if

users

have
supplied

this
)


There

is
indoor

navigation (
if

users

have
enabled

this
)


2

Indoor

Positioning

via
Wi
-
Fi


SmartCampusAAU

uses

Wi
-
Fi

technology

when

GPS signals
are

absent
.


Wi
-
Fi

infrastructures

are

ubiquitous

and
Wi
-
Fi

is
available

in
modern

Smartphones


This

means

that

indoor

positioning

and navigation
can

be

made
available

in
any

building

to
any

user

(
carrying

a
Smartphone
).


However
,
indoor

positioning

is
hard
:
When

Wi
-
Fi

signals
are

transmitted

from an
access

point,
they

are

attenuated
,
scattered

and
reflected

by
obstacles

like

walls
,
furniture

and
even

people
.


The
result

is
highly

unpredictable

signal
propagations

which

means

that

traditional

lateration

techniques

have
difficulties

in
providing

accurate

position
estimates


Instead
, the most
accurate

technique

is
called

location
fingerprinting
.


The location
fingerprinting

technique

is
based

on
measuring

actual

signal
strengths

from
access

points.


The location
fingerprinting

technique

is
able

to
provide

location
estimates

within

3 meters of a
user’s

actual

position.

3

How

Location
Fingerprinting

works


Location
fingerprinting

is split
into

two

phases
:


Offline
:


In
order

to
make

indoor

positioning

possible
, a
so
-
called

radio
map

must
first

be

built
.


A radio
map

is a database
that

contains

signal
strength

information for
different

coordinates

throughout

a
building
.


A radio
map

is
incrementally

built

in the
following

way
:


A
user

stands at a
certain

location and marks her location on a
map
.


The
user

then

starts
measuring

signal
strengths

for
about

10
seconds
.


Finally
, the <location,
measurement
> information is
saved

in a server
-
side
radio
map
.


This

process

is
repeated

at
different

locations
until

the
entire

indoor

environment

has
been

covered

by
measurements
.


Online
:


If a radio
map

has
been

built
,
indoor

positioning

is
now

enabled
.


A
user

can

be

estimated

by the system to
be

at
any

of the locations
where

users

have
measured

signal
strengths

in the offline
phase
.

4

5

Location
Fingerprinting

-

The Offline
Phase



AP1

AP3

AP3

AP1 =
-
40

AP2 =
-
70

AP3 =
-
95

(x1, y1, z1)

AP1 =
-
45

AP2 =
-
60

AP3 =
-
85

AP1 =
-
65

AP2 =
-
55

AP3 =
-
75

AP1 =
-
80

AP2 =
-
45

AP3 =
-
60

(x2, y2, z1)



(x3, y3, z1)

(x4, y4, z1)

(…)

Radio
Map

Signal
strengths

are

measured

at the
starred

locations

6

Location
Fingerprinting

-

The Online
Phase



AP1

AP3

AP2

AP1 =
-
55

AP2 =
-
40

AP3 =
-
80

(x1, y1, z1)

AP1 =
-
40

AP2 =
-
60

AP3 =
-
95

AP1 =
-
40

AP2 =
-
70

AP3 =
-
85

AP1 =
-
35

AP2 =
-
90

AP3 =
-
55

(x2, y2, z1)



(x3, y3, z1)

(x4, y4, z1)

(…)

Radio
Map

AP1 =
-
50

AP2 =
-
40

AP3 =
-
85

The
user

can

be

estimated

to
be

at
any

of the
starred

locations

SmartCampusAAU


The
SmartCampusAAU

app

implements

the location
fingerprinting

technique

as
described

on the
previous

pages.


In the offline
phase
, the
SmartCampusAAU

app

can

be

used

to
build

a radio
map
.


Moreover, in the offline
phase

users

can

build

a
graph

of
the
indoor

environment

(
establishing

links
between

locations).


The
graph

can

be

used

to
enable

indoor

navigation.


(The
graph

is
also

used

to
improve

the
positioning

accuracy
)


In the offline
phase
,
users

can

also

supply

semantic

information
about

locations.

7

Walkthrough

of the
SmartCampusAAU

app


The
SmartCampusAAU

app

can

be

used

to
enable

indoor

positioning

in a
building

via the location
fingerprinting

technique
.


The
remaining

pages
details

how

this

is
accomplished
.


First
,
we

describe

the offline
activities

that

are

required

to
enable

the online
positioning

and navigation
functionality
:

1.
Add

a
building

and
building

floors

(
this

only

needs

to
be

done
once
)

2.
Build

a radio
map



to
enable

indoor

positioning

3.
Supply

semantic

(i.e., human
readable
) information.

4.
Build

a
graph



to
enable

indoor

navigation




(The ”Offline Mode” is
accessed

by
choosing

MENU
-
>
Offline

Mode

when

the
app

starts)

8

1
-
a)
Add

new
building

9

(1)

(2)

(3)

1
-
a)
Add

a new
building


The
very

first

step is to
add

a new
building

to the
system


This

is
only

needs

to
be

done
once

(
when

no

radio
map

exists
) by the
very

first

contributor
.

1.
A
building

should

be

given a
readable

name
,
e.g
., ”Empire State Building” and an
optional

(official)
url
.

2.
The
building

should

then

be

positioned

globally

by
marking

its

location on Google
Maps
.

3.
The system
will

suggest

an
appropriate

address
.

10

1
-
b)
Add/Edit

building

floors

11

Edit

Floor

New
Floor

(1)

(2)

1
-
b)
Add/edit

building

floors


The
second

step is to
add

floors

to the
building


Even
if

a
building

only

has
one

floor

it must still
be

added

to the system.


In the Offline Mode,
choose

MENU

-
>
Edit

Graph

-
>
Edit

Building
Floors
.
This

will

bring up screen (1).

1.
This

shows the
floors

that

have
been

added

to the
system.
You

can

now

either
:

1.
Add

a new
floor

2.
Edit

an
existing

floor

2.
When

adding

or

editing

a
floor

it must
be

given a
floor

number

as
well

as a
floor

name
.

12

2
-
1)
Add

measurement

(
extend

or

update

the radio
map
)

13

Add

measurement

to new location

Add

measurement

to
existing

location

(1)

(2)

2
-
1)
Add

measurement

(
extend

or

update

the radio
map
)


When

you

are

in the Offline Mode
you

can

see

a
number

of
icons



these

icons

represent

the
places

where

other

users

have
measured

signal
strengths

(and
hence
, locations
where

the system
can

estimate

users

to
be
).

1.
You

can

add

a new location to the radio
map

by
clicking

a location
on the
map

and
choosing

MENU
-
>
Measure
.


You

can

fine
-
tune

the location by
choosing

MENU
-
>
Enable

D
-
pad
.
This

will

give
you

a
little

joystick to
nudge

the location up,
down

or

sideways
.


Make

sure
that

you

have
choosen

the
correct

floor

(
MENU
-
>
Change

Floor
)

2.
You

can

also

update

an
existing

location by
clicking

its

icon

and
choosing

”New Measurement”.
Updating

existing

locations
will

help

to
continuously

improving

the
positioning

accuracy

of the
system
.



IMPORTANT!
Make

sure
you

stand in the location
you

marked on
the
map
.



14

2
-
2)
Measuring

signal
strengths


15

(1)

(2)

(3)

2
-
2)
Measuring

signal
strengths


When

you

have
opted

to
measure

signal
strengths

at a location
you

are

brought

to
screen (1) on the
preceeding

page.


It is
important

that

you

remain

in the position
that

you

marked on the
map

during

the
measurement

process
.

1.
You

start a
measurement

by
clicking

the ”Start”
button
.

2.
This

will

will

up a dialog
that

shows the
number

of
Wi
-
Fi

scans

that

have
currently

been

performed
.


The
measurement

process

is
stopped

by
clicking

”Stop”.


The more
scans

you

take

before

click

”stop” the
better
.
We

recommend

a
minimum of 10
scans
, but
even

more
scans

will

have a
beneficiel

effect

on
the
positioning

accuracy

of the system.

3.
When

the
measurement

process

is done a list of
access

points
that

could

be

heard

is
shown
.


If
you

know

that

some

access

points do not
belong

to the
building
,
please

unmark

them
.
Otherwise
, just
leave

all
access

points marked.


The final step is to save the
measurement

by
clicking

the ”
Upload

Selected

button
.

16

17

3
)
Add

semantic

information

(1)

(2)

(3)

3)
Add

semantic

information


When

a new location has
been

added

to the radio
map

you

will

notice

that

it is
represented

by a ?
-
icon

on the
map
.


This

means

that

the system is
now

able

to position
users

at
that

location.


You

can

also

associate

semantic

information (i.e., human
readable

information) by
clicking

on the location and
choosing


Edit

Location”.
This

will

bring
you

to screen (1) on the
preceeding

page.

1.
You

can

specify

the
following

details

for a location:
Title
,
description

and
url

for the location.
You

should

mark the
field

”Is
Entrance

if

the
location
represents

an
entrance

into

the
building

2.
You

can

specify

some

properties

for the location (
e.g
.,
whether

the
location is an
office
,
lecture

room
, etc.).
This

will

be

reflected

in the
icon

that

is
shown

for the location

3.
This

shows an
example

of
having

added

semantic

information to a
location. The
location’s

title

is ”
Canteen
”, the
description

says


Open

11
-
13” and
there

is a URL
which

will

show
further

details

for
canteen
. The
location
was

marked as ”Food”
which

shows in the
icon
.

18

4)
Add

links

19

(1)

(2)

(3)

4)
Add

links


In
order

to
enable

indoor

navigation
you

need

to
add

links
between

neighbouring

locations
where

it is
physically

possible

to
move

between
.


In the Offline Mode
you

choose

MENU
-
>Edit

Graph
-
>Edit

Links.

1.
You

add

a link by
clicking

on
two

neighbouring

locations
that

are

not
yet

connected

and
then

choose

MENU
-
>Add

Link.
This

will

bring
you

to screen (2)

2.
On
this

screen
you

specify

properties

for the link. ”None”
means

that

there

are

no

special

properties
;
otherwise

you

can

indicate

whether

the locations
are

connected

via an elevator
or

stairs
.

3.
This

shows a link
that

is
now

connection

two

locations.



The procedure for
removing

a link is
identical

except

you

should

click

on
two

locations
that

are

already

connected

and
then

choose

MENU
-
>Remove

Link.

20

Online Mode


Assuming

the
four

steps in the Offline mode
have
been

done,
indoor

positioning

and
navigation is
now

enabled

in the
building
.


When

the
SmartCampusAAU

app

starts up it is
in the
online mode

where

indoor

positioning

and navigation
functionality

can

be

used
.


The
following

pages
demonstrate

the online
functionality
.

21

Indoor

Positioning



Choose

Provider

22

Indoor

Positioning



Choose

Provider


In
MENU
-
>Choose

Provider

you

can

choose

between

different

location
providers
:


GPS:
Uses

GPS for
positioning
.
Appropriate

for
outdoor

usage
.


Wi
-
Fi
:
Uses

Wi
-
Fi

(location
fingerprinting
) for
positioning
.
Appropriate

for
indoor

usage
.


When

switching

to
Wi
-
Fi
, the system
will

detect

and
download an
appropriate

radio
map

and
then

start
positioning
. The system
will

automatically

change

floors

when

the
user’s

current

location
changes

floor
.


None:
Turns

off

positioning
.
Appropriate

for
saving

energy

when

positioning

is not
needed
.

23

Online Options


MENU
contains

the
available

online options


You

can

see

which

points of
interest

are

available

on the
current

floor
,
you

can

search

for points of
interest
, and
you

can

change

floor
.

24

Tracking

Position
On/Off

25

Tracking

enabled

Tracking

disabled

Tracking

means

that

the
the

map

will

center
around

the
user’s

current

position.

Tracking

can

be

disabled

by
panning

on the
map

or

changing

floor

from the menu.

Also
, the
tracking

button

in top
left

corner

can

be

used

to
enable/disable

tracking

Navigation

26

Summary


The
SmartCampusAAU

app

relies

on end
user

participation (
aka

crowdsourcing
) to
enable

indoor

positioning

and navigation.


Users

enable

indoor

positioning

via location
fingerprinting


Users

enable

indoor

navigation by
adding

links
between

locations.


Users

supply

semantic

information
about

indoor

locations


27