Paolo Cravini Piaggio & C. S.p.A(Italy), paolo.cravini@piaggio SP1 & SP4 Partner

1SAFESPOT – SP1 SAFESPOTApril 23rd Schwieberdingen

Paolo Cravini

Piaggio & C. S.p.A(Italy), [email protected]

SP1 & SP4 Partner

SP1 - SAFEPROBESP1 - SAFEPROBESP1 - SAFEPROBESP1 - SAFEPROBEScenario AnalysisScenario Analysis


Scenario AnalysisUC 7

PTW falling on the roadway

• PTW falls down on a section of a single/dual carriageway and stay motionless on the road surface

VA VB = 0

S0



PTW falling on the roadway

• PTW falls down on a section of a single/dual carriageway and stay motionless on the road surface

Vehicle B – PTW - Transmitter

• Speed sensor

• GPS

• Tilt sensor

Vehicle A – SAFEPROBE Vehicle - Receiver

• Safespot platform



PTW overtaking OV while OV making a turn

• Vehicle B suddenly changes lane on the trajectory of the incoming vehicle A (PTW)

VAVB

S0



Vehicle A – PTW - Transmitter

• Speed sensor

• GPS

Vehicle B – SAFEPROBE Vehicle - Receiver

• Safespot platform

PTW overtaking OV while OV making a turn

• Vehicle B suddenly changes lane on the trajectory of the incoming vehicle A (PTW)


: start speed of vehicle A and B

: start relative distance between vehicles (t=0)

: limit value of mean deceleration (PTW is roughly 8 m/sec2)

,A BV V0sLIMa

Scenario AnalysisCalculation

Safety Margin ConceptData

VA VB

S0


Vehicle B proceeds with

Vehicle A starts to decelerate at

Only the case is considered

Safety Margin ConceptAssumptions (after starting manoeuvre)

const.BV R LIMa a

A BV V


VA VB

S0


Approximate stop distance :

Where is the typical reaction time

Safety Margin ConceptDefinitions

2

2A

T ALIM

Vs V

a

1s


VA VB

S0


– Decelerate motion of vehicle A :

– Motion at constant speed (vehicle B) :

– Relative distance between the vehicle (after braking)

Safety Margin ConceptEquations of motion

0( )B Bs t s V t

0A BV V V


( )A As t V t 0 t

21( ) ( )

2A A Rs t V t a t t

20

1( ) ( ) ( ) ( )

2B A Rs t s t s t s V t a t

Before braking

After braking


– To avoid collision must assumes always positive values


( )s t

*

0t t

s

t

That is the time corresponding to the

minimum relative distance


*

R

Vt

a




VA VB

S0

22 2*

0 0

( ) 1 ( )( )

2 2RR R R

V V Vs t s a s V

a a a


Safety Margin ConceptAdimensional parameter

0

T

s

s 2 0 • If start distance is equal to stop distance 1

B

A

V

V 1 0 • If vehicles are travelling at the same speed 1

R

LIM

ak

a 1 0k • If deceleration is equal than the limit value 1k



Safety Margin ConceptEquations of motion in terms of , ,k


VA VB

S0

2 2 2* (1 )

( ) ( 1)2 2

A AA

LIM LIM

V Vs t V

a ka


VA VB

S0

• Which is the minimum value for for deceleration of vehicle A in order to avoid collision with vehicle B ? This is expressed by the following condition

Safety Margin Concept

*( ) 0s t and by setting [sec]A

LIM

V

a



VA VB

S0

• Which is the minimum value for for deceleration of vehicle A in order to avoid collision with vehicle B ? This is expressed by the following condition



2

min min

(1 )( , , )

2 ( 1)k k


• Previous equation gives as output the minimum value of deceleration to avoid collision between vehicles. It is function of 5 parameters that can be monitored by the SAFESPOT system




• The information could be transmitted to the driver of vehicle B in terms of driving conditions


min0 0,5k

min0,5 0,75k

min0,75 1k

COMFORTCOMFORT

SAFETYSAFETY

CRITICALCRITICAL




Critical Crash

Increasing driver intervention needed to prevent the crasht

Safety Margin

SafetyComfort



• Data :

– Start speed of vehicle A : VA = 10 m/sec

– Start speed of vehicle B : VB = 6 m/sec

– Relative distance between vehicles (t=0) : S0 = 20 m

– Limit value of mean deceleration (PTW is roughly 8 m/sec2) : aLIM

– PTW deceleration : aR = 6 m/sec2

– Reaction time : τ = 1 sec

Example – User Case 8 – Comfort Situation



• Results :

– Stop distance vehicle A : ST = 16.25 m

– Delta ST = 14.66 m – minimum relative distance

– Time corresponding to minimum relative distance : t* = 1.66 sec


– Kmin = 0.06 (Comfort Situation)

The minimum relative distance is the space between the vehicle at the end of the manoeuvre

Example – User Case 8 – Comfort Situation



• Data : The real situation (car turning in front of the PTW) could be analysed by

considering the car speed at the turning point equal to zero

– Start speed of vehicle A : VA = 10 m/sec (previous comfort situation)

– Start speed of vehicle B : VB = 0 m/sec (new situation)





Example – User Case 8 – Safety Situation



• Results :


– Delta ST = 1.66 m – minimum relative distance



– Kmin = 0.625 (Safety Situation) – The safety margin decrease due to

VB = 0

The minimum relative distance is the space between the vehicle at the end of the manoeuvre

Example – User Case 8 – Safety Situation



• Data :

– Start speed of vehicle A : VA = 11 m/sec (new situation)

– Start speed of vehicle B : VB = 0 m/sec (previous safety situation)





Example – User Case 8 – Critical Situation



• Results :


– Delta ST = -1.08 m (crash event)



– Kmin = 0.84 (Critical Situation)

Example – User Case 8 – Critical Situation


Paolo Cravini Piaggio & C. S.p.A(Italy), paolo.cravini@piaggio SP1 & SP4 Partner

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