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Vehicle Stability Control & other Acronyms!
Vehicle Stability Control?? What does it all mean?
Vehicle Stability Control, Dynamic Stability Control, Electronic Stability Program!! the list goes on. There are increasingly more and more electronic stability safety driving aids being fitted to vehicles these days. The grandfather of them all ABS has just about become standard now on all production vehicles sold in the UK. With Stability Management systems also quickly spreading across vehicle ranges. We have compiled some more detailed information to help you understand the differences in some of the systems available today and how it might not be as good as you think it is supposed to be.
Utilises Mercedes' ASR (Automatic Skid Reduction) this system is a very basic traction control system that can only reduce the chance of a loss of control from excessive acceleration. It does this by cutting engine power when the ABS sensors detect wheel spin from the driven wheels.
It will more than likely be unable to keep the car from spinning in the wet?
Trivia: A zonda is a dry, winter wind that descends from the Andes' eastern slopes. It usually precedes the pampero, a severe thunderstorm with rain, thunder and lightning.
Maserati Gran Sport Spider
MSP, EBD, ASR
The Maserati Gran Sport Spider boasts all of the technological and safety features offered by the Maserati range of GTs, but with some very important refinements. The car has the same sophisticated set-up as the Coupé Cambiocorsa: a transaxle layout with the gearbox rear-mounted in unit with the differential, stability and traction control (MSP) integrating ABS, ASR, MSR and EBD functions, which can be deactivate if desired, and the Skyhook adaptive damping system which instantly adapts the damper calibrations to suit the driving and road conditions and allows the driver to choose between two different settings (Normal and Sport).
As with the other models in the Maserati range, the driver can choose between two levels of gear changing. Normal mode is more comfortable and typical of Grand Tourer driving, while with a touch of the Sport button on the central console they get to feel the true power of the car. The Sport mode delivers much faster gear changing, a deeper exhaust sound and less invasive use of the MSP stability and traction control system.
The BMW M6 boasts a brand-new generation of Dynamic Stability Control. With the first stage of DSC being conceived for maximum driving safety, the M Dynamic mode, as on the M5, is tailored to the sporting driver this changes the threshold of activation but ultimately works the same by reducing the torque and activating the brakes individually. Pressing a button on the selector lever cover, the driver is able to switch off DSC. When you switch off the DSC, it's completely off, unlike other makes where some electronic safeguards remain.
EDC Electronic Damper Control on the BMW M6 offers the driver the choice of three programs available on demand: Comfort, Normal, and Sports, with the car's chassis and suspension ranging from sporting and taut all the way to - relatively - smooth and comfortable. The driver operates EDC via the MDrive button on the steering wheel or the push button next to the SMG selector lever.
CATS, DSC, EBA
Jaguar’s Computer Active Technology Suspension system, CATS – is further enhanced, and standard on the XKR. This is an electronic control system, which combines uprated springs to increase roll stiffness with adaptive dampers to optimise ride refinement – This sophisticated technology allows the XK to be two kinds of car in one package – a true sports car, but with the comfort of a luxury grand tourer. In simple terms, CATS works by continuously adjusting the damping characteristics to suit driving conditions, optimising both ride and handling. A series of sensors provide information to the electronic control unit, which is mapped to deliver the best solution to dampers that can switch between firm and soft settings in milliseconds. When the car is started, damping defaults to the firm setting, but switches to the softer setting once the car is travelling at more than 5mph (8kp/h) on a smooth, straight road. When the XK encounters bumps, or during cornering and braking, the settings switch instantaneously to the firmer mode, reducing roll and increasing stability.
DSC: Dynamic Stability Control
Dynamic Stability Control is one of the XK’s front-line electronic safety features. It is not a substitute for careful and considered driving, but it does allow performance potential to be responsibly explored, with a powerfully reassuring back up.
This active system enhances safety at the car’s limits of grip and road holding, which is especially valuable when road conditions are poor. Unless it is manually switched off (in which case a warning light in the dashboard will remind the driver that they are travelling without DSC) the system operates automatically whenever the engine is running. A warning light also flashes when the system is intervening to restore stability.
A series of sensors detect specific kinds of motion and send information to the Electronic Control Unit (ECU), which in turn activates a hydraulic modulator that interacts with the braking system. The sensors detect the speed of each wheel (and more importantly their relative speeds) for both the ABS and DSC systems; monitor the steering angle at the steering wheel rim (inputs of as little as one-and-a-half degrees or about 5mm of wheel movement can be detected); measure yaw rate, which is the rate of rotation of the vehicle about a vertical axis and indicates that it is understeering at the front or oversteering at the rear; lateral acceleration – the sideways cornering force – and also measure hydraulic brake pressure, to interpret whether or not the brakes are being applied.
Essentially, the system uses the steering wheel angle to interpret the direction in which the driver intends the car to go and compares that with the direction actually taken by the vehicle. If the onset of instability – either understeer or oversteer – is recognised, the system takes measures to restore stability, either by reducing engine torque via the ECU, selectively applying gentle braking to one or more wheels, or both. Working with the drive-by-wire throttle and the ABS system, it will make corrections to enable the car to follow the driver’s steering input. If the driver tries to keep the throttle open the DSC will reduce the power anyway and if the driver does not apply brake pressure, DSC will. The system also intervenes to prevent wheel spin, again by automatically reducing power and if necessary braking individual wheels.
DSC does not discourage a driver from enjoying the full abilities of the XK's highly developed chassis; rather it allows the car to be driven enjoyably, but with a safety net. Controlling wheel spin can actually improve acceleration, especially on surfaces with uneven grip. And because it can be switched off, the wheel spin-controlling element of DSC will not leave the driver stranded in special circumstances, such as when snow chains are fitted, or when trying to drive out of deep, soft snow or sand.
If the system has been switched off and the sensors detect an emergency situation, DSC will automatically re-engage as soon as the brakes are applied. What's more, the DSC system is tuned specifically to match the characteristics of the XK. The manner in which it makes corrections depends on the problem it is correcting. If the car over steers in a left-hand corner, for example, (with the tail sliding outwards) DSC will apply the right-front brake to provide a corrective effect. If the car under steers in a left-hand corner (with the nose pushing wide) it will apply the left-rear brake to help turn into the corner. If the problems are caused by too much power being applied, DSC will reduce power.
EBA: Emergency Brake Assist
Research shows that even in emergency situations most drivers do not apply the maximum possible braking pressure. This prevents those drivers from entering the 'ABS zone', the area of maximum braking efficiency immediately prior to the point where the wheels lock and the anti-lock function comes into action. Jaguar's Emergency Brake Assist (EBA) system is designed to overcome this. When EBA detects a rapid application of the brake pedal it interprets it as an emergency braking situation and automatically applies the additional pressure that the driver has not provided, producing maximum braking effort. Not only that, but it does so more quickly than the driver could. This can dramatically cut braking distance, with obvious safety benefits.
Porsche 911 GT3
PASM (Porsche Active Suspension Management) allows the driver to choose between two default settings of suspension stiffness, soft and passive for normal day-to-day road use. Along with a firmer mode for smooth track work. Although the system is continuously variable and adjusts as it sees fit, taking its readings from nearly all-electrical elements of the car. The system will appear to have reduced the traction if set to the sport setting on a wet road. Traction control (TC) bolsters the GT3’s mechanical locking differential, which provides 28 per cent lock-up under power and 40 per cent on the overrun. ABD brakes the first spinning wheel in a pull off wheel spin situation. TC is based on the system from the Carrera GT and steps in when wheel spin becomes excessive at speeds above 25 mph; it does this by cutting the engine power ASR. Its effectiveness is changed when the sport button is pressed making it unlikely to prevent a spin situation when getting on the throttle too much, too soon in the wet. It also acts (MSR) to limit engine braking on the overrun to prevent locking up of the wheels on over-ambitious downshifts. It can be switched off.
The Michelin Sport Cup tyres will appear to give noticeably less traction when the ambient temperature is below 8 degrees Celsius. Warming up these almost competition tyres is very advisable!
Porsche 911 Turbo
Porsche Traction Management (PTM) ensures variable power distribution to the two driven axles. Depending on the driving conditions, the all-wheel electronics system constantly determines the optimal torque distribution to ensure the best possible traction. In practice this translates to high agility on narrow country roads, outstanding traction in rain and snow and optimal active safety at all speeds. These properties make the Porsche Traction Management system in this 911 Turbo one of the most capable and, at the same time lightest, all-wheel drive systems on the
This latest evolution of Porsche Stability Management (PSM) provides automatic assistance in critical road scenarios. A powerful driver aid, it uses a range of sensors to monitor the direction, speed, yaw velocity (speed of rotation around the vertical axis) and lateral acceleration of the car. With this information, it can then calculate the actual direction of travel. If the car begins to oversteer or understeer, PSM applies selective braking on individual wheels to bring it safely back into line. Whenever PSM is required to intervene, an indicator light in the cockpit is illuminated.
Another scenario in which PSM is invaluable is when applying the throttle on wet or other low-grip surfaces. Here, PSM uses the ABD (automatic brake differential) and
ASR (anti-slip regulation) functions in PTM to maintain traction and stability.
Standard equipment on the 911 Turbo, PSM assists with high precision
inputs that enhance the athleticism and agility of the car. When ‘Sport’ mode is selected on the optional Sport Chrono Package Turbo (see page 60),
the PSM threshold is raised higher still enabling greater driver involvement – particularly at speeds of up to 70 km/h (44 mph). The integral ABS ensures shorter
braking distances in critical road scenarios. System inputs are smooth and precise for greater driver comfort. Active safety is further enhanced with the aid of
two additional brake functions: electronic brake prefill and brake assist.
The prefill function is automatically enabled whenever the throttle pedal is suddenly released. The pressure in the brake lines is marginally increased, bringing each of the pads into light contact with the corresponding disc. If the driver then decides to use the brakes, the system can apply the maximum force with virtually no delay.
The brake assist function is specifically designed for use in emergency stops. When the pressure on the brake pedal exceeds a predefined threshold, the brake assist function uses the PSM hydraulics to apply the pressure required for maximum
deceleration. The result: shorter braking distances. For a more natural drive, PSM can be manually disabled leaving only the automatic brake differential (ABD) in place. Although essentially inactive, PSM remains present in the background and can intervene immediately under heavy braking where at least one front wheel requires ABS assistance. In ‘Sport’ mode, PSM will only respond when ABS is active on both front wheels. In short, PSM provides the ideal balance between electronically assisted active safety and freedom to enjoy the car’s potential
PASM as on the GT3 above but with softer settings overall, the firmest setting in the Turbo is the softest setting in the GT3.
CST Control, Stability, Traction
As well as the start button, the steering wheel also houses a dial, known by Scuderia Ferrari drivers as the Manettino. It controls the electronics for the suspension settings, the CST (Control, Stability and Traction), the speed of the transmission and the E-Diff or Electronic Differential. A version of E-Diff has been used in F1 cars for a number of years and has developed into the system found, for the first time in a road car, in the F430. It transfers torque to the wheels when cornering hard and thus improves road holding, away from the racetrack.
The Manettino has five settings; ‘Ice’ is for low-grip situations where increased CST input is needed. In this situation, the system prohibits the use of paddle-changes. ‘Normal’ is exactly that with damping set to comfort mode. ‘Sport’ is for maximum performance on the road and offers a good compromise between stability and oomph. The suspension becomes firmer and the CST allows a bit of leeway before intervening. Then there’s ‘Race’ for track use, In this case the CST input is kept to a minimum and the gearshifts are faster than the normal 150 milliseconds.
Finally, the ‘CST ' selection is used in conjunction with the Launch Control (LC) button unless you live in the USA, where it is not available. Again, only for use on a track, the dial is held in the CST position for three seconds and the LC button is pressed. You then put your foot on the brake and rev the engine to 5,000rpm before releasing the brake. Madness! With the CST off, the only aids left are ABS with EBD and a firm grip on the steering wheel.
Bentley Continental GTC
The Bentley Roll Over Protection System (ROPS) is effectively to rear long bars that are fired up from behind the rear headrests to help protect any occupants in the event of a roll over situation. The car monitors the body’s overall stability and if it feels it is going over or is about to roll over will activate the bars, this could see the bars activate if a driver takes the car over a hump back bridge or similar hump fast and makes the car actually leave the ground or get near to this situation.
The ESP system is a Bosch system that is becoming more and more common on a rapidly increasing list of vehicles. It incorporates the ASR, (anti-slip regulation) and MSR (engine drag torque control) elements in order to be an all round system that makes it very difficult to lose control of the car, no matter what the cause. It cannot how ever just like all the others listed here defy the laws of physics.
HBA (hydraulic brake assist) EBD (electronic brake distribution) are elements contained within the ABS system and will be in most modern cars systems that have four channel ABS.
As above ESP is the BOSCH system that incorporates just about every acronym that exists in modern stability management. ABD, ASR, ABS, EBD, HBA, MSR and so on!! It makes it very difficult to lose control of the vehicle no matter what you do, apart from just go too fast!!!
As above BOSCH ESP.
Aston Martin DB9/V8 Vantage
Again the BOSCH ESP system given another name by Aston Martin and is very similar to the software used on the BMW hence the same acronym.