Innovative Wireless Sensor for Vehicle on Board Cooperative Systems

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Innovative Wireless Sensor for Vehicle on Board Cooperative Systems

ong>Innovativeong> ong>Wirelessong> ong>Sensorong> ong>forong>

ong>Vehicleong> On-board Cooperative

Systems

ong>Innovativeong> techniques to accurately

detect Vulnerable Road Users (VRU)

ong>forong> Traffic Safety Applications


Introduction:

• In this presentation we describe the results of

AIT contribution to the FP6 “WATCH-OVER”

project.

• Main Objective of Project was to the reliable

detection of the relative position of VRUs.

• AIT task was the evaluation and testing of

telecommunication wireless signal when used as

automotive sensors ong>forong> traffic safety applications.

10/22/2010 2


WATCH-OVER Scenario:

• VRU Detection

R

R T

R

Optional 2nd VRU

R R

R T

T

R …Receiver

… Transmitter

T … optional Transmitter

R … optional Receiver

∆t … propagation time of the reflected signal

d = ∆t/2

R T

10/22/2010 3


Measurement Set-up – System Overview

CAR

VRU

Switch

80MS/s

16bit

DSP

DSP

DSP

DSP

DSP

D

D

D

D

D

40MHz BB

140MHz

A

A

A

A

A

IF

RF

IF

RF

IF

RF

IF

RF

IF

RF

f 2

f 1

40MHz BB

140MHz

RF

IF

RF

IF

LO2 LO1

The measurement‘s frequencies are:

T

R

R

… Transmitter

…Receiver

… optional Receiver

Clk Sync

LO1 LO2

f 1

= 2660 MHz

f 2

= 2520 MHz

10/22/2010 4


Measurement Set-up

• Transmitter and Receiver Car-side

10/22/2010 5


Measurement Set-up

• Transceiver VRU-side

• VRU Antenna: λ/4-antenna, 2400-2700MHz, Z = 50Ω, horizontal omni-directional

10/22/2010 6


Measurement Set-up

• Receive Antenna Spacing

d = 1,4m d = 0,26m

Antenna car: 3 patch antennas, f = 2300-2800MHz, Z = 50Ω, gain = 7,5dBi

10/22/2010 7


Measurement Test Scenarios

• Tested Scenarios:

1. Pedestrian (or cyclist) moving along the

street

2. Pedestrian (or cyclist) crossing the road

3. Pedestrian (or cyclist) crossing the road

occluded from parked car

10/22/2010 8


Measurement Set-up

• Transmission Signal

R(s(t))

0.4

0.2

0

-0.2

Transmit Signal

• Complex signal (I,Q) generation with

Matlab

• PN Sequence: typical UMTS downlink

sequence

• Transmit filter: Root Raised Cosine, α =

0,22

• Signal active time: 8,6µs

• Repetition time: 80,6µs 12,4kHz

-0.4

0 1

time [sec]

2

x 10 -4

10/22/2010 9


Estimation of Delay

• Smart Antenna

• Signal s(t) and r i

(t) oversampled to 1GSPS

• Correlation

80

10 3 Delay [sec]

10 2

Ch0

Ch1

Ch2

70

60

50

Ch0

Ch1

Ch2

40

10 1

30

20

10

10 0

0 0.5 1 1.5 2

0

1.0285 1.029 1.0295

Delay [sec]

1.03 1.0305

x 10 -4

Reference channel (Ch0) and the receive channels (Ch1 and Ch2)

x 10 -4

10/22/2010 10


Estimation of Delay

• AoA (Angle of Arrival)

• Signal r i

(t) and r i+1

(t) oversampled to 1GSPS

• Correlation

• Phase of maximum

c


′( 2 3

t

τ

τ ) = ∑ r ( t)

r ( −τ

)

ϕ = angle(max( c′ ( τ )))

• Geometric angle

α = asin( ϕλ /(2πd

))

10/22/2010 11


Estimation of AoA (Angle of Arrival)

• Unambiguos Angle Estimation:

• it is only possible to estimate the angle unambiguously when d ≤ λ/2

3

2

d=lambda/2

d=0.205m

d=1.4m

1

a'(φ)

0

-1

-2

-3

-3 -2 -1 0 1 2 3

angle [rad]

Theoretical phase shift of different antenna spacing

10/22/2010 12


Field Measurements – Smart Antenna

• Delay and Distance

Measurement

Scenario

Antenna

spacing

Distance car -

VRU

1 b 1.4 m 10 m

Measurement

Delay

MSE (Ch1/Ch2)

Delay

RMSE [s]

Distance

RMSE [m]

1 1.4e-17 / 1.2e-17 3.8e-9 / 3.5e-9 1.127 / 1.057

• Example of scenario b with T snap

= 1 ms

10/22/2010 13


Field Measurements – Smart Antenna

• Angle of Arrival

Measurement

Scenario

Antenna

spacing

Distance car -

VRU

6 b 0,26 m 10 m

Measurement MSE RMSE [rad] RMSE [deg]

6 0.0018 0.0421 2.4098

• Example of scenario b, continuous measurement T = 3s

10/22/2010 14


Field Measurements – Triangulation

• Position Estimation through Geometry

• VRU Distance:

α =

⎛ d

arccos



2

1

+ b

2d

2

1

− d

b

2

2




2

⎛ b ⎞ 2

= ⎜ ⎟ + d1

− bd cos α

⎝ 2 ⎠

d

1

• VRU angle:


⎜ d


ϑ = arccos




2

⎛ b ⎞

+ ⎜ ⎟

⎝ 2 ⎠

db

2

− d

2

2







10/22/2010

15


Results Comparison of Smart Antenna

versus Triangulation

• Smart Antenna (2 antennas): RMSE angle: ± 2,0º

– Antenna distance: 0,26 m

• Triangulation:

– Antenna distance: 1,4 m Typical error: ± 21º

R

T

R

T

… Transmitter

d1,2

γ

d2

d 1

d 2

R

… Receiver

d1

d ~ ∆t/2

∆t … propagation time of the reflected signal

R

T

10/22/2010 16


ong>Vehicleong> On-board Realisation

ong>Wirelessong> ong>Sensorong>s Integration Concept

½ λ Smart

Antennas

Processing Unit

Camera

Radar

ong>Sensorong>s and processing unit integrated next to driving mirror

– Advantages: Protected, limited vibrations, clean environment

10/22/2010 17


Cooperative System

• Integration of VRU sensor unit with onboard

cooperative system

On-board VRU sensor unit

HMI – Visual and

Acoustic Inong>forong>mation

• All sensors are networked, the data is provided to the on board Cooperative

System where a decision will be made if and how to inong>forong>m the driver, other

nearby vehicles or the infrastructure network.

10/22/2010 18


Conclusions:

• Implementation options and limitations on vehicle

– Antenna Aperture angle selection and planning ong>forong> optimum VRU detection, position on

vehicle of Antennas and additional sensors.

• Benefits of ong>Wirelessong> positioning

– Increase detection accuracy of VRU, allows early detection of non visible VRUs, adds

reliability to Cooperative ong>Sensorong> Systems.

• Standardisation and large deployment

– RF Bandwidth, Frequencies and Communication protocols will need to be defined

– C2C, C2I, I2C, DSRC are not planned ong>forong> VRU detection (limited RF Bandwidth)

– 4G (LTE and WiMAX) has the technical features (RF Bandwidth up to 40 MHz) suitable ong>forong>

wireless VRU Detection.

• Outlook and trends

– From the results of several EU funded projects, Cooperative Systems and Cooperative

Communications (CALM, DSRC, etc. etc.) are recognised to be the way to improve Road-

Safety and Mobility.

ong>Wirelessong> Architectures and Protocols are being proposed ong>forong> European standardisation in

national projects.

10/22/2010 19


Thank you

ong>forong> your attention!

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