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Revolutionary ESP with steering intervention as of 2005, first of all in the Golf
New generation of ESP helps the driver to countersteer specifically
From mid-2005 onwards, Volkswagen will be launching a new generation of ESP for the Golf and other models with targeted power-assisted steering. Depending on the situation, the electronic stabilisation program sends impulses to the steering that cause the driver to move intuitively to countersteer correctly. In this way, ESP + driving recommendation contributes to reducing the braking distance by up to 10%, in particular on roads with different coefficients of friction (for example dry on the left, wet or snow-covered on the right).
The new system configured in this way can be used exclusively in conjunction with vehicles which – like the new Golf – have electromechanical power steering or another active steering system. This is why Volkswagen decided at a very early stage to launch the Golf onto the market with an “active” steering system as standard.
New ESP provides impulses for thinking and steering: the actual decisions remain fully within the authority of the driver
Important: the new ESP does not assume the job of really steering the car, the actual decisions are to remain fully within the authority of the driver. It is much more the case that it provides a steering recommendation – even though this is clearly noticeable (with a maximum torque of 3 Newton metres). The example of road surfaces with different coefficients of friction shows in detail how efficiently the system intervenes: it is winter; one half of the road is dry, the other half still has patches of snow.
ESP today: everything happens at the wheel with the lowest grip
Until now, the ideal scenario on these road surfaces with different coefficients of friction (known as µ split in technical jargon) in the case of full braking with ESP has been: thanks to ESP, the car does not start skidding; the driver is able to keep the car on track and avoid the obstacle.
However, as the braking effect has to orient itself to the wheel with the poorer coefficient of friction (here: on snow) in order to prevent the vehicle from swerving, the car cannot be braked as strongly as would actually be possible if the wheels were on a dry surface. Without countersteering in the correct direction, the car would swerve due to the “overbraking” of one wheel, as the asymmetric braking forces support a rotational tendency of the car towards the side of the road with better grip.
ESP tomorrow: the wheel with the higher adhesion can now really get to grips
It is precisely here that the new ESP with driving recommendation sets in: the system “recognises” the direction in which the driver must countersteer to be able to brake the car without swerving. This is why the unit sends the command to the electromechanical power steering to issue a steering impulse in the required direction. The driver senses this, intuitively complies with the signal, and countersteers in the classical manner. This stabilising intervention means that the brake pressure at the wheels with the greatest grip can be increased. The consequence: the braking distance is reduced by up to 10%.
ESP and EPS: Electrical Power Steering in the new Golf
All of this only becomes possible by networking ESP with an electromechanical steering system (EPS, Electrical Power Steering), as in the Golf. This is a so-called dual-pinion steering system. The power-assisted steering is provided by a servo motor. The two pinions (steering and drive pinion) apply the required steering force onto both the steering column and servo side into the conventional rack. Here, the steering pinion transfers the steering torque applied directly by the driver; the drive pinion transfers the power-assistance torque from the servo motor via a worm gear. This configuration means that there is always a mechanical connection between the steering wheel and the steering gear; the vehicle even remains steerable after failure of the servo motor. For the driving recommendation via ESP, this servo motor performs the key function, as it triggers the impulse in the steering wheel for countersteering.
Alongside the numerous dynamic advantages, the Golf steering system provides yet another decisive advantage: as the electromechanical solution – in contrast to the conventional hydraulic solution – only “works” in the case of a steering manoeuvre, the average consumption during real vehicle operation falls by approximately 0.2 litres.
During development, particular attention was paid to the sense of centring when driving straight ahead. The steering torque that builds up even with the smallest steering angles underscores the exact sense of centring. A contributing factor here is the active return of the steering; after cornering, the steering wheel returns automatically towards driving straight ahead. In addition, the “self-learning” steering features straight-ahead driving correction. The background: the system itself recognises inclinations in the road and countersteers this accordingly. The straight-ahead driving correction thus offers a significant comfort enhancement, as the driver remains relaxed and keeps the Golf on track without steering effort.
ESP + Trailer Stabilisation
The Touareg is the first Volkswagen that can be supplied with trailer stabilisation
An ESP software extension makes driving with trailers safer
The electronic stabilisation program has revolutionised active safety in the automobile. However, the technical evolution of ESP is anything but over. Especially the software for control of the ESP provides astonishing potential. The best example: ESP + trailer stabilisation. This is a pure software extension of ESP without an additional sensor system.
Initially, Volkswagen will be deploying the ESP + trailer stabilisation for classical towing vehicles such as the Touareg: the system makes most sense here due to relatively frequent trailer journeys and high trailer loads (Touareg: 3500 kilos, braked). At a later date, trailer stabilisation will also be offered for the Multivan.
Although the Touareg in particular, with its very balanced chassis, the optional or standard (V10 TDI) air suspension and of course four-wheel drive, enable extremely safe operation with a trailer, vehicle combinations can of course be subject to body roll – for example due to strong side winds, improper loading, lane grooves or evasive manoeuvres. Here, even experienced drivers are frequently out of their depth.
With the trailer stabilisation of the Touareg, rolling trailers are detected (via the ESP control unit) even as they start to roll by the characteristic vibrations initiated in the towing vehicle. The system excludes incorrect interventions by means of a comprehensive plausibility check of all ESP signals. In the specific emergency situation, the vehicle combination is decelerated via the ESP by braking the towing vehicle at all wheels and reducing the engine torque until the body roll has been eliminated.
As this is targeted braking, the brake lights are activated automatically – even if the brake pedal is not pressed.
The electronic stabilisation program coordinates active safety
The new Golf has the most modern system of this kind on board
The most advanced ESP on the market operates in the current Golf – though it is still without steering intervention. This ESP function is not included in the system, either. However, the important yawing moment control (YMC) – recording and correction of the vehicle rotation where required – is what can be termed the core function of the ESP. Before it was used in automobiles, yaw rate sensors were used exclusively in aerospace applications. However, as a general principle: the ESP coordinates active safety in association with a large number of electronic and mechanical modules. The major ESP functions include:
- Anti-lock Braking System (ABS).
- Traction Control System (TCS).
- Hydraulic Brake Assistant (HBA / in the Golf, Dual Brake Assist).
- Electronic Differential Lock (EDL).
- Yawing Moment Control (YMC / actual ESP function).
- Rear Axle Full Deceleration (HVV / actively increases the pressure on the rear axle when the front wheels are already subject to ABS control, but the rear wheels are not).
- Low Dynamic ESP (LDE / can intervene in the event of small deviations when the vehicle is braked although the vehicle is still stable).
- Engine Braking Control (EBC).
- Overboost (additional hydraulic boosting).
- Corner Braking Logic (CBC / regulates braking forces between the left-hand and right-hand side of the vehicle).
In order to be able to deploy and combine the various functions where it makes sense, the ESP permanently compares measurement data on the actual handling characteristics with what the driver wishes to do. These important parameters are supplied via the wheel speed, yaw rate, lateral acceleration and wheel angle sensors
If the system determines a deviation from stable handling, it stabilises the car by means of individualised brake application at each wheel and intervention in the engine management. However, development in networking with the ESP is still a long way from its final stage. The Phaeton is an example: here, the system also co-operates with the dynamically regulated air suspension chassis. In the next stage, which will come from mid-2005 onwards, the activation of the steering as outlined above will be added for the first time.
ESP Accident Research
ESP saves 800 human lives per year in Germany
Volkswagen introduced ESP in 1998, first of all in the Passat and then in the Golf
More than 80% of all the Volkswagen passenger cars sold in Germany are equipped with the electronic stabilisation program (ESP). Current research in this field showed that ESP, after the seat belt, has developed into the most important lifesaver in road traffic. Approximately 800 people per year owe their lives to the electronic stabilisation program.
Volkswagen introduced the system as early as 1998 in the Passat and Golf model series. Since then, there has been a revolution in active safety. With ESP, it became possible for the first time to defuse dangerous situations by means of active control; until then, even with the best basic chassis and suspension, these situations were likely to have led to severe accidents. With the alliance of high passive safety (crash safety, restraint systems) and active safety (chassis, brakes), the rate of serious injuries in road traffic is declining from one year to the next. In 2003, according to the Federal Bureau of Statistics, the number of fatal traffic accidents in Germany reached a new minimum; it is the lowest value since statistics were introduced in the year 1953.
The electronic stabilisation program and the brake assistant, which is also used as standard in many Volkswagens, make a major contribution to so-called accident severity reduction or even to avoiding accidents. The following example illustrates this: Volkswagen Accident Research initiated a study to analyse the influence of ESP using a total of 382 real accidents that could be evaluated. Of the main group of vehicles that caused accidents which were not equipped with ESP, 107 began skidding; of the vehicles with ESP, skidding was registered on only four of them. This means: ESP reduces the risk of skidding by approximately 85%.
With the deployment of new driver assistance systems such as ESP + driving recommendation, Volkswagen will continue in future to make a significant contribution to reducing the number of people injured or killed in road traffic. Today in Germany, for certain versions of the Lupo and Polo as well as for all variants of the Golf, Bora, New Beetle, Touran, Sharan, Passat, Touareg and Phaeton, ESP is on board as series standard.
Euro NCAP: as regards the total of individual results, the new Golf is the safest car in its class
The Volkswagen safety philosophy protects all road users
The combined effects of active and passive safety create a particularly effective protection system. On the one hand, the people in the vehicle are protected. In just the same way, however, pedestrians or cyclists are protected by the fact that ESP actively enables the driver to avoid them more easily. Furthermore, on the passive side, the softer configuration of the body in the relevant areas means that the car does not hit these other road users as hard as it otherwise would. For Volkswagen, this holistic approach to the issue of safety – an analysis from the point of view of all those theoretically involved in a dangerous situation – has the highest priority. The key word here is partner protection.
This systematic partner protection is ideally illustrated by the new Golf, as the current results of the Euro NCAP crash progam show: the Golf achieved not only the maximum of five stars for occupant protection in the case of head-on and side impacts, but also the best values for pedestrian protection (three of four possible stars) and child protection (four of five possible stars). A result of this kind has never been achieved before by any other vehicle in this class tested by Euro NCAP. This efficient overall protection was made possible by the outstandingly rigid occupant cell and highly effective restraint systems, plus excellent partner protection in the body area.
For example, child protection: the highest degree of safety has been achieved here by means of the Isofix attachment of the child seats in conjunction with an additional upper belt (top tether).
For example, pedestrian protection: in the event of an accident involving pedestrians, the new Golf has systematically deformable deformation zones in the front-end, combined with an additional cross-member in the bumper, to achieve significantly lower risk of injury and thus genuine partner protection.
Golf versus off-road vehicle: Volkswagen best-seller masters ADAC crash test with flying colours
The expression “partner protection” in the classical sense of the car crash test stands for another scenario: collisions between large and small automobiles. Volkswagen, as a manufacturer of vehicles of all classes, also systematically integrates this aspect into the holistic view of vehicle development. As an example, the Golf once again: the crash experts of the ADAC (German motorists’ association) examined in an unusual test how the Golf and its passengers survive in a so-called offset crash (frontal with overlap) against large off-road vehicles. In the first crash, the Golf had to compete with an off-road vehicle of modern design (with self-contained body); in the second crash, another Golf had to deal with an off-road vehicle of conventional design (with ladder-type frame).
The Volkswagen, almost one tonne lighter, mastered both crashes with flying colours. All the more remarkable is the balance with which the Golf – due to its “softer” body zones – endangers pedestrians and cyclists as little as possible on the one hand, but on the other hand has an extremely rigid occupant cell with a hard core that guarantees the best possible protection for everyone on board.
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