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Do not touchyour ESC button!
Do not touch your ESCbutton. ESC is switchedon by default when you startyour vehicle, so it does notrequire switching on. Somemanufacturers are producingcars without the ESC button(e.g. Ford), so that drivers are
protected by ESC at all times.The majority of cars are ttedwith an ESC button whichcan be used to switch ESCoff when unusual conditionsare encountered, such asmoving off in deep snow. TheESC button should not be
touched unless those unusualconditions are encountered.For further information,please consult your vehiclehandbook.
ESC is particularly effective in poor driving conditionssuch as ice and snow.
A study for the UK Department for Transport by Loughborough Universityhas shown that on UK roads, cars tted with ESC are 25% less likelyto be involved in a fatal accident than those without ESC. If every vehiclewere tted with ESC, this would equate to 380 fewer fatal accidentsannually. Serious crashes involving skidding or overturning could bereduced by up to 59%.
What are the benets?
is ESC ?whatESC is often soldwith differentnames: ESP, VSA,DSTC and others.
ESC is a major safety featurewhich could save your life
Electronic Stability C ontrol, ESC, helpsto prevent the driver from losing controlin a skid. ESC automatically controls the vehicle by comparing thesteering actions carried out by the driver to what the vehicle is actually doing.If the ESC senses that the vehicle is veering from the required course a skid it automatically brakes selected wheels to bring the car back into line.
OversteerIf you swerve to avoid anobstacle such as a rapidlane change on a motorway,oversteer can occur makingthe vehicle turn more thanintended, ultimately leadingto a spin. ESC can preventthis by braking individualwheels to maintain control.
UndersteerIf you are driving too fastinto a corner, understeercan occur. This would resultin a loss of steering controlas your car continues to followa straight path and not steeras required. ESC can helpretain steering control andallow the car to travel in thedesired direction.
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Outriggers tted to the VolkswagenTransporter to prevent risk of rollover
ut does ESCally work?hilst the tment ratingslp to inform consumersout buying cars ttedth ESC, it is a completelyfferent question to verifyat ESC actually works.Thatcham has been
sting ESC systems
dynamically since 2008,following an internationaltest procedure. The aimof this dynamic testing is toverify that the ESC systemsare actually operating asthey should do. Euro NCAPhas followed suit and isnow testing cars in thesame way.
LegislationIn the US, there is aregulation (FMVSS 126)that requires ESC to bemandatory on all cars by2012. This regulationhas been proposed asa GTR (Global TechnicalRegulation). In Europe ESCwill be compulsory for newtypes of car from November
2011, and for all newcars by November 2014.The regulations includespecication of the ESCsystem components andfunctionality, the ESCon/off switches, and tell-tales on the dashboardas well as the dynamictest procedure.
Thatcham has been publishing ESC tment ratings for the last fewyears to raise awareness of this important safety technology, and to
encourage drivers to buy cars tted with ESC. Manufacturers haverisen to the challenge and now more widely t ESC as standard.
Thatcham has a programme ofdynamic testing of vehicles forESC functionality, in additionto the publication of tmentratings (see www.thatcham.org/esc). This dynamic testingis based on the procedure inthe GTR 8 which assessesthe performance requirementsof the ESC system, resultingin either a pass or fail. Forgreater detail on the testprocedure and assessmentcriteria, please also seeResearch News specialedition on ESC 2009.
A steering robot is requiredto carry out this testing whichtakes over from the driver toprovide the steering input in asafe, precise and repeatable
way. The test has severalstages and begins with brakeand tyre conditioning. Aslowly increasing steer testis performed to dene thesteering wheel angle input Afor the Sine with Dwell. Thetest is then performed afteranother series of the tyreconditioning runs. The test isa Sine with Dwell manoeuvreat 50mph and comprisesa sinusoidal steer in onedirection, followed by a steerin the opposite direction, witha dwell of 500 millisecondsat the second peak. The runsare repeated with both theleft and right initial inputs. Theruns start with a small steeringinput and build up to asteering wheel angle of 270.
Time
S t e e r
i n g w
h e e
l a n g
l e
-
Sine with Dwell steering input usedfor dynamic ESC test
dynamictesting
The runs startwith a smallsteeringinput andbuild up toa steeringwheel angleof 270.
The latest tment ratingsfor 2010 are available atwww.thatcham.org/esc
criteria
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ove:esponsive vehicle:L (lateral displacement
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Alfa Romeo Guilietta
FinalHeading(greatest
magnitude)
21.5
Stability CriterionResponsiveness CriterionGTRPass
Aston Martin DB9
FinalHeading(greatest
magnitude)
41.4
Stability CriterionResponsiveness CriterionGTRPass
Alfa Romeo MiTo
FinalHeading(greatest
magnitude)
42.3
Stability CriterionResponsiveness Criterion
GTRPass
Audi A1
FinalHeading(greatest
magnitude)
36.3
Stability CriterionResponsiveness Criterion
GTRPass
The test results are compiledfor the sample of vehiclestested since 2008. For thispublication, graphics areprovided as an indicationof the lateral displacement
and yaw velocity accordingto the GTR. The additionalcalculation of nal heading isprovided in the table. Resultsdata is also available atwww.thatcham.org/esc
resultsdynamic test
esultsAudi A4
FinalHeading(greatest
magnitude)
29.9
Stability CriterionResponsiveness Criterion
GTRPass
Citron C3 Picasso
FinalHeading(greatest
magnitude)
17.4
Stability CriterionResponsiveness Criterion
GTRPass
Audi Q5
FinalHeading(greatest
magnitude)
41.0
Stability CriterionResponsiveness Criterion
GTRPass
Citron C4
FinalHeading(greatest
magnitude)
12.1
Stability CriterionResponsiveness Criterion
GTRPass
BMW 5-Series
FinalHeading(greatest
magnitude)
18.4
Stability CriterionResponsiveness Criterion
GTRPass
Citron DS3
FinalHeading(greatest
magnitude)
36.2
Stability CriterionResponsiveness Criterion
GTRPass
BMW X1
FinalHeading(greatest
magnitude)
15.2
Stability CriterionResponsiveness CriterionGTRPass
Ford C-Max
FinalHeading(greatest
magnitude)
15.5
Stability CriterionResponsiveness CriterionGTRPass
Chevrolet Cruze
FinalHeading(greatest
magnitude)
31.4
Stability CriterionResponsiveness Criterion
GTRPass
Ford Fiesta
FinalHeading(greatest
magnitude)
34.7
Stability CriterionResponsiveness Criterion
GTRPass
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Honda Accord
FinalHeading(greatest
magnitude)
12.7
Stability CriterionResponsiveness Criterion
GTRPass
Hyundai i20
FinalHeading(greatest
magnitude)
18.0
Stability CriterionResponsiveness Criterion
GTRPass
Honda Civic
FinalHeading(greatest
magnitude)
39.9
Stability CriterionResponsiveness Criterion
GTRPass
Hyundai iX35
FinalHeading(greatest
magnitude)
12.4
Stability CriterionResponsiveness Criterion
GTRPass
Honda CR-Z
FinalHeading(greatest
magnitude)
35.5
Stability CriterionResponsiveness Criterion
GTRPass
Jaguar XF
FinalHeading(greatest
magnitude)
29.9
Stability CriterionResponsiveness Criterion
GTRPass
Honda Insight
FinalHeading(greatest
magnitude)
24.4
Stability CriterionResponsiveness CriterionGTRPass
Kia Soul
FinalHeading(greatest
magnitude)
24.2
Stability CriterionResponsiveness CriterionGTRPass
Honda Jazz
FinalHeading(greatest
magnitude)
30.1
Stability CriterionResponsiveness Criterion
GTRPass
Kia Sportage
FinalHeading(greatest
magnitude)
14.6
Stability CriterionResponsiveness Criterion
GTRPass
Kia Venga
FinalHeading(greatest
magnitude)
24.6
Stability CriterionResponsiveness Criterion
GTRPass
Mercedes E-Class E220 CDi
FinalHeading(greatest
magnitude)
27.9
Stability CriterionResponsiveness Criterion
GTRPass
Mazda 3 Sport
FinalHeading(greatest
magnitude)
57.5
Stability CriterionResponsiveness Criterion
GTRPass
Mercedes E-Class E350
FinalHeading(greatest
magnitude)
13.9
Stability CriterionResponsiveness Criterion
GTRPass
Mazda 3 TS2
FinalHeading(greatest
magnitude)
60.3
Stability CriterionResponsiveness Criterion
GTRPass
MINI Countryman
FinalHeading(greatest
magnitude)
12.5
Stability CriterionResponsiveness Criterion
GTRPass
Mazda 6
FinalHeading(greatest
magnitude)
20.1
Stability CriterionResponsiveness CriterionGTRPass
Mitsubishi Lancer
FinalHeading(greatest
magnitude)
20.8
Stability CriterionResponsiveness CriterionGTRPass
Mazda CX-7
FinalHeading(greatest
magnitude)
19.6
Stability CriterionResponsiveness Criterion
GTRPass
Nissan Cube
FinalHeading(greatest
magnitude)
18.9
Stability CriterionResponsiveness Criterion
GTRPass
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Peugeot 3008
FinalHeading(greatest
magnitude)
17.5
Stability CriterionResponsiveness Criterion
GTRPass
Saab 9-5
FinalHeading(greatest
magnitude)
22.8
Stability CriterionResponsiveness Criterion
GTRPass
Peugeot 308
FinalHeading(greatest
magnitude)
25.8
Stability CriterionResponsiveness Criterion
GTRPass
Seat Exeo
FinalHeading(greatest
magnitude)
14.5
Stability CriterionResponsiveness Criterion
GTRPass
Peugeot 308cc
FinalHeading(greatest
magnitude)
13.7
Stability CriterionResponsiveness Criterion
GTRPass
Skoda Superb
FinalHeading(greatest
magnitude)
37.0
Stability CriterionResponsiveness Criterion
GTRPass
Peugeot 5008
FinalHeading(greatest
magnitude)
11.7
Stability CriterionResponsiveness CriterionGTRPass
Skoda Yeti
FinalHeading(greatest
magnitude)
49.2
Stability CriterionResponsiveness CriterionGTRPass
Renault Grand Scenic
FinalHeading(greatest
magnitude)
31.3
Stability CriterionResponsiveness Criterion
GTRPass
Subaru Impreza RC
FinalHeading(greatest
magnitude)
47.7
Stability CriterionResponsiveness Criterion
GTRPass
Subaru Impreza WRX STI
FinalHeading(greatest
magnitude)
39.3
Stability CriterionResponsiveness Criterion
GTRPass
Toyota Prius
FinalHeading(greatest
magnitude)
18.9
Stability CriterionResponsiveness Criterion
GTRPass
Suzuki Swift
FinalHeading(greatest
magnitude)
62.0
Stability CriterionResponsiveness Criterion
GTRPass
Toyota Urban Cruiser
FinalHeading(greatest
magnitude)
25.2
Stability CriterionResponsiveness Criterion
GTRPass
Toyota Avensis
FinalHeading(greatest
magnitude)
13.3
Stability CriterionResponsiveness Criterion
GTRPass
Toyota Verso
FinalHeading(greatest
magnitude)
15.3
Stability CriterionResponsiveness Criterion
GTRPass
Toyota iQ
FinalHeading(greatest
magnitude)
14.7
Stability CriterionResponsiveness CriterionGTRPass
Vauxhall / Opel Astra Exclusiv CDTi
FinalHeading(greatest
magnitude)
46.4
Stability CriterionResponsiveness CriterionGTRPass
Toyota Land Cruiser
FinalHeading(greatest
magnitude)
10.9
Stability CriterionResponsiveness Criterion
GTRPass
Vauxhall / Opel Astra SRi
FinalHeading(greatest
magnitude)
42.4
Stability CriterionResponsiveness Criterion
GTRPass
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Vauxhall / Opel Insignia
FinalHeading(greatest
magnitude)
40.3
Stability CriterionResponsiveness Criterion
GTRPass
Volkswagen Scirocco
FinalHeading(greatest
magnitude)
40.1
Stability CriterionResponsiveness Criterion
GTRPass
Vauxhall / Opel Meriva
FinalHeading(greatest
magnitude)
17.3
Stability CriterionResponsiveness Criterion
GTRPass
Volkswagen Sharan
FinalHeading(greatest
magnitude)
12.9
Stability CriterionResponsiveness Criterion
GTRPass
Volkswagen Golf 5
FinalHeading(greatest
magnitude)
52.3
Stability CriterionResponsiveness Criterion
GTRPass
Volkswagen Tiguan
FinalHeading(greatest
magnitude)
17.7
Stability CriterionResponsiveness Criterion
GTRPass
Volkswagen Golf 6
FinalHeading(greatest
magnitude)
38.2
Stability CriterionResponsiveness CriterionGTRPass
Volkswagen Transporter
FinalHeading(greatest
magnitude)
13.0
Stability CriterionResponsiveness CriterionGTRPass
Volkswagen Polo
FinalHeading(greatest
magnitude)
28.2
Stability CriterionResponsiveness Criterion
GTRPass
Volvo XC60
FinalHeading(greatest
magnitude)
23.4
Stability CriterionResponsiveness Criterion
GTRPass
Citron DS3: GTR Pass
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All the new cars tested to date have passed thisdemanding ESC dynamic test. This shows thatthese cars, which are sold as having ESC systemstted, also have the functionality to operate
and maintain control of the car in this severemanoeuvre. However, they do not all performthe same way, and some differences betweenthe systems are revealed.
throttle response and ESCsystem (known as VehicleDynamic Control (VDC)by Alfa Romeo). In Dynamic
Mode, the MiTo actuallyfailed the ESC test, sodrivers must be aware ofhow these systems operateto ensure they are protectedby ESC at all times. This isan example which highlightsthe differences betweenESC systems. Whilst all carspass the GTR test, the ESCsystems do not necessarilyintervene in the same way.
Driving modesThe Alfa Romeo MiTo has asystem called DNA, meaningDynamic, Normal and AllWeather driving modes. Thissystem adjusts the steering,
not all ESC systems are
equal
nterventionsESC
ESC InterventionsWhilst all the cars pass the GTR test, the results indicatethat ESC application varies greatly between vehicles.
All cars achieved a pass on the responsiveness criterionaccording to the GTR. In further analysis, the smallestdisplacement was selected for each vehicle, whichrepresents the run that is closest to a failure. There wasa large range in these lateral displacements, and thisindicates the wide variety in performance of the vehiclestested. The Toyota Land Cruiser had the smallest lateraldisplacement, whereas the Alfa Romeo MiTo had thelargest. Whilst a displacement closer to 1.83m is closerto failure according to the GTR, it is also possible thata larger displacement could pose a risk. A greaterdisplacement might indicate departure from thecarriageway, with associated risk of collision.
Some systems intervenepromptly to avoid loss ofcontrol. However, othervehicles allow much greateryaw velocities beforeintervention. All the vehiclestested passed the stabilitycriterion according to theGTR but there was a widevariety in responses. Thegreatest magnitude yawvelocity was selected for
each vehicle, which representsthe run that is closest to afailure since the ideal resultis 0%. The range at 1 secondafter completion of steer wasfrom -15% to 17% (fail is over35%), and at 1.75 secondsthe yaw velocities ranged from-7% to 4% (fail is over 20%).Again, this indicates the widevariety in performance ofthe vehicles.
T h e T o y o
t a L a n d C r u i s e r h a d t h e s m a l l e s t l a t e r a l
d i s p l a c e m e n t
. . . t
h e S u z u
k i S
w i f t h a d t h e l a r g e s t
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SubaruThe Subaru Impreza RC is anexample of a large negativeyaw velocity, and in particular,this has a larger magnitudethan the positive value. Thisnegative value represents ayaw in the opposite direction.
In many cases, the car willexperience both positive andnegative yaw velocities as itsettles following the steeringinput.
Time (s)
Yaw velocity (/s)PassSteering RobotAngle ()
-
-
--
-
-
-
.
-
-
-
-
-
-
- -
-
-
-
-
-
-
-
-
-
-
l
-90
-70
-50
-30
-10
10
30
50
70
90
-1 0 1 2 3 4 5
-300
-200
-100
0
100
200
300
Yaw velocity-15%
l
Y a w v e
l o c i
t y ( / s )
Mazda 3 TS2: exampleof a large positive yaw velocity
MazdaThe Mazda 3 TS2 is anexample of the greatestmagnitude (17%) of yawvelocity shown in thetesting. This shows thata large amount of yaw is
allowed before the ESCsystem intervenes.
-
-
--
-
-
-
.
-
-
- -
-90
-70
-50
-30
-10
10
30
50
70
90
-1 0 1 2 3 4 5
-400
-300
-200
-100
0
100
200
300
400
Yaw velocity17%
-
-
-
-
-
-
-
-
- l
-
-
-
-
-
-
-
-
-
-
l
Y a w v e
l o c i
t y ( / s )
Time (s)
Yaw velocity (/s)PassSteering RobotAngle ()
Subaru Impreza RC: exampleof a large negative yaw velocity
rangeperformance
Suzuki Swift: example of large nalheading
SuzukiThe Suzuki Swift had thegreatest nal heading of 62,which was the largest of allthe cars tested. This vehiclealso had the greatest yawvelocity result of 16% at 1second after COS, which isalso one of the highest. Thehigher the yaw velocity andthe longer the duration, themore the vehicle turns, andtherefore the greater the nalheading. Once the steeringmanoeuvre is completed andthe steering wheel returnsto straight ahead, the ESCsystem has to work to controlyaw and bring the vehicle pathback in line with the
drivers intention. A larger nalheading might increase therisk that the vehicle leavesthe carriageway, which mayconsequently pose a greatercollision risk.
Volkswagen Tiguan: exampleof tightly controlled yaw velocity
VolkswagenThe Volkswagen Tiguan isan example of a vehicle withvery tight control on the yawvelocity, which returns to zerovery quickly after the steeringmanoeuvre. However, this
might be attributed to the rollcontrol elements of the systemrather than directly to the ESCsystem (that controls yaw).
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
- l
-
-90
-70
-50
-30
-10
10
30
50
70
90
-1 0 1 2 3 4 5Time (s)
-300
-200
-100
0
100
200
300
Yaw velocity 0%
Y a w v e
l o c
i t y ( / s )
Yaw velocity (/s)PassSteering RobotAngle ()
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In 2006, Thatcham beganto produce tment ratingsfor ESC, and found thatonly 40% of UK models
were being sold with ESCtted as standard. Now,after 5 years, this gurehas increased to 75%.
ESC has recently beenmade a regulatoryrequirement globally. Allbrand new models soldmust be tted with ESC asstandard from 2012, and allcars including facelifts andupdates by 2014. Lookingback at the standardtment rates in 2008,the increase in standardtments compared to
2007 was only 6%; but for2010 tments comparedto 2009, that increasehas doubled to 12%. We
are now beginning to seethe increase in standardtments that is required bythe impending regulatoryrequirements.
New modelstted withstandard ESCThe majority of newmodels are being broughtto market with ESC ttedas standard. Some oldercars remain available withESC not available or asan option. Car buyersmight want to save some
money during these timesof economic pressure,but compromising vehiclesafety capability is surely
a high risk strategy.Thatcham recommendsthe purchase of a car ttedwith ESC, even if it costsmore. For full informationabout the ESC tments,please refer to the websitewww.thatcham.org/esc .The tment informationcan be used to helpinform people makinga car purchase about theavailability of ESC, whetherit is a new car purchaseor an older car.
For ESC tment information:www.thatcham.org/esc
2006 2010
29%
7%
75%
4%
40%
27%
4%
14%
Not available at all
Optional across the entire range
Standard across the entire range
Combination of fitment
NOTE: ESC cannot defy the laws of PhysicsIf you are travelling too fast for the road conditions,ESC can only try to help prevent an accident occurring.
Real world example of a single vehicle rollover crash,where ESC might be effective. ESC UK tment
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