Post on 02-Feb-2016
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1SAFESPOT – SP1 SAFESPOTApril 23rd Schwieberdingen
Paolo Cravini
Piaggio & C. S.p.A(Italy), paolo.cravini@piaggio.com
SP1 & SP4 Partner
SP1 - SAFEPROBESP1 - SAFEPROBESP1 - SAFEPROBESP1 - SAFEPROBEScenario AnalysisScenario Analysis
2SAFESPOT – SP1 SAFESPOTApril 23rd Schwieberdingen
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
3SAFESPOT – SP1 SAFESPOTApril 23rd Schwieberdingen
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
Vehicle B – PTW - Transmitter
• Speed sensor
• GPS
• Tilt sensor
Vehicle A – SAFEPROBE Vehicle - Receiver
• Safespot platform
4SAFESPOT – SP1 SAFESPOTApril 23rd Schwieberdingen
Scenario AnalysisUC 8
PTW overtaking OV while OV making a turn
• Vehicle B suddenly changes lane on the trajectory of the incoming vehicle A (PTW)
VAVB
S0
5SAFESPOT – SP1 SAFESPOTApril 23rd Schwieberdingen
Scenario AnalysisUC 8
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)
6SAFESPOT – SP1 SAFESPOTApril 23rd Schwieberdingen
: 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
7SAFESPOT – SP1 SAFESPOTApril 23rd Schwieberdingen
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
Scenario AnalysisCalculation
VA VB
S0
8SAFESPOT – SP1 SAFESPOTApril 23rd Schwieberdingen
Approximate stop distance :
Where is the typical reaction time
Safety Margin ConceptDefinitions
2
2A
T ALIM
Vs V
a
1s
Scenario AnalysisCalculation
VA VB
S0
9SAFESPOT – SP1 SAFESPOTApril 23rd Schwieberdingen
– 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
Scenario AnalysisCalculation
( )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
10SAFESPOT – SP1 SAFESPOTApril 23rd Schwieberdingen
– To avoid collision must assumes always positive values
Safety Margin ConceptEquations of motion
( )s t
*
0t t
s
t
That is the time corresponding to the
minimum relative distance
Scenario AnalysisCalculation
*
R
Vt
a
11SAFESPOT – SP1 SAFESPOTApril 23rd Schwieberdingen
Safety Margin ConceptEquations of motion
Scenario AnalysisCalculation
VA VB
S0
22 2*
0 0
( ) 1 ( )( )
2 2RR R R
V V Vs t s a s V
a a a
12SAFESPOT – SP1 SAFESPOTApril 23rd Schwieberdingen
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
Scenario AnalysisCalculation
13SAFESPOT – SP1 SAFESPOTApril 23rd Schwieberdingen
Safety Margin ConceptEquations of motion in terms of , ,k
Scenario AnalysisCalculation
VA VB
S0
2 2 2* (1 )
( ) ( 1)2 2
A AA
LIM LIM
V Vs t V
a ka
14SAFESPOT – SP1 SAFESPOTApril 23rd Schwieberdingen
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
Scenario AnalysisCalculation
15SAFESPOT – SP1 SAFESPOTApril 23rd Schwieberdingen
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
Scenario AnalysisCalculation
2
min min
(1 )( , , )
2 ( 1)k k
16SAFESPOT – SP1 SAFESPOTApril 23rd Schwieberdingen
• 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
Safety Margin Concept
Scenario AnalysisCalculation
17SAFESPOT – SP1 SAFESPOTApril 23rd Schwieberdingen
• The information could be transmitted to the driver of vehicle B in terms of driving conditions
Safety Margin Concept
min0 0,5k
min0,5 0,75k
min0,75 1k
COMFORTCOMFORT
SAFETYSAFETY
CRITICALCRITICAL
Scenario AnalysisCalculation
18SAFESPOT – SP1 SAFESPOTApril 23rd Schwieberdingen
Safety Margin Concept
Critical Crash
Increasing driver intervention needed to prevent the crasht
Safety Margin
SafetyComfort
Scenario AnalysisCalculation
19SAFESPOT – SP1 SAFESPOTApril 23rd Schwieberdingen
• 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
Scenario AnalysisCalculation
20SAFESPOT – SP1 SAFESPOTApril 23rd Schwieberdingen
• 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
– Relative distance between vehicles (t=0) : S0 = 20 m
– 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
Scenario AnalysisCalculation
21SAFESPOT – SP1 SAFESPOTApril 23rd Schwieberdingen
• 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)
– 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 – Safety Situation
Scenario AnalysisCalculation
22SAFESPOT – SP1 SAFESPOTApril 23rd Schwieberdingen
• Results :
– Stop distance vehicle A : ST = 16.25 m
– Delta ST = 1.66 m – minimum relative distance
– Time corresponding to minimum relative distance : t* = 2.66 sec
– Relative distance between vehicles (t=0) : S0 = 20 m
– 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
Scenario AnalysisCalculation
23SAFESPOT – SP1 SAFESPOTApril 23rd Schwieberdingen
• Data :
– Start speed of vehicle A : VA = 11 m/sec (new situation)
– Start speed of vehicle B : VB = 0 m/sec (previous safety situation)
– 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 – Critical Situation
Scenario AnalysisCalculation
24SAFESPOT – SP1 SAFESPOTApril 23rd Schwieberdingen
• Results :
– Stop distance vehicle A : ST = 23.56 m
– Delta ST = -1.08 m (crash event)
– Time corresponding to minimum relative distance : t* = 2.83 sec
– Relative distance between vehicles (t=0) : S0 = 20 m
– Kmin = 0.84 (Critical Situation)
Example – User Case 8 – Critical Situation
Scenario AnalysisCalculation