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  Keeping one step ahead

March 2005

According to statistics provided by Robert Bosch, skidding is the cause of one quarter of all accidents. They also show that 60% of all accidents with fatal injuries happen through side crashes caused mainly by skidding.

To combat this bête noire of the road, Bosch devised an anti-lock braking system ABS, the shorthand which sprang from the German word antiblockiersystem, in 1976. While it had a relatively slow take-up to begin with, it has become such a de facto part of the car that it has become a standard in Europe so that all cars sold in the 25 countries that comprise the European Union must have it fitted. However, Bosch is still not satisfied and for the last 10 years, it has been selling its Electronic Stability Program (ESP) system, a system that detects skidding almost before it starts and actively counteracts that, but the success rate has been patchy. While some 64% of all new vehicles in Germany were fitted with ESP in 2004, the overall share for Europe as a whole is just 36% for the same period. The installation rate is even lower in other parts of the world with the US, for example, recording just over 10%, although Bosch is confident that it will change following the announcement by the Big Three that most SUVs will be equipped with ESP as standard by 2006.

Various studies have reinforced the benefits of ESP in 2004. DaimlerChrysler, for example, said that the standard fitment of ESP in all Mercedes-Benz passenger cars had reduced their incidence in “driving accidents” in Germany by around 42%. A “driving accident” is defined as one in which the driver loses control of the vehicle without other road users being involved. A NHTSA (National Highway Traffic Safety Administration) study also showed that passenger cars that had been fitted with ESP as standard equipment from 1997 to 2002 had, on average, 35% less driving accidents than for the same vehicle models before the standard fitment of ESP, with the number of fatal driving accidents reduced by 30%. In the SUV class, the impact was even greater: according to the study, the number of road accidents in this category was reduced by 67% and fatal road accidents reduced by 63%.

With all these statistics in mind, whether it be the number of vehicles that still do not have ESP fitted as standard or else the number of accidents and fatalities that can be reduced, Bosch is going on the offensive not only to try and get better market acceptance and penetration, but even to get it written into a standard, as has happened with anti-lock braking in Europe. Already 2005 has been declared as the year of ESP by a member of the European Commission and upheld by the EU Commissioner responsible for traffic, so certain lawmakers are “on message”.

However, the public at large, whether it be fleet operators or the general public, still obstinately refuse to acknowledge the benefits of ESP, even if they have heard of it or know what it does. Bosch market research showed that while British drivers, for example, had a good awareness of passive safety systems such as airbags (89%) and seatbelts (76%), only 18% identified ABS as an active safety system and just 1% nominated ESP. In a world where ABS, even 27 years later, is still perceived as having a “super-braking” effect rather than as a methodology of anti-skid whereby the driver is less likely to lose control, it does look like it could an uphill battle for the German company. To this end, Bosch has launched the ESPerience dealer training program to improve awareness through dealerships, it now has 50 ESPerience training centres located around the world and it has developed 5 ESP simulators that are currently on a worldwide tour.

As is the way with technology, though, we are into new generations of ESP with the main focus being on networking the passive safety systems with predictive driver assistance aids. Bosch has incorporated these functions into the CAPS – Combined Active and Passive Safety Systems – program. Additionally, Bosch is developing a scalable product line on the basis of ESP. As in airlines where there is economy, business and first class, so there are going to be three different levels of ESP.



At its most basic is ESP, ESP plus (business class) and ESP premium (first class) and while they would not divulge prices, it was clear talking to different engineers that there would be price premiums to pay on the advanced systems. ESP plus, for example, which will start to be seen on some cars this year, has added functionality that include traffic jam assist whereby the driver of a car with automatic transmission can take his or her foot off the throttle pedal and allow the braking system to initiate a slow deceleration and electronic brake pre-fill. ESP premium will offer automatic brake disc wiping and be linked into the adaptive cruise control system for stop and go.

“We have changed the pump system and the pump concept,” says Hubertus Wienken, a senior engineer at Bosch working on the next-generation ESP systems. “Normally there are two pump elements that provide the active pressure build up, but with CAPS we have six pump elements – three for each circuit. This is because it is quicker with a higher hydraulic flow rate, but it is around 4 kg heavier than ESP 8 – the current ESP generation. The hydraulic flow rate is up to 98 per cent lower.”

The six pump system means that there is less vibration on the pedal during ABS intervention and pedal comfort is much better than on normal ESP. A high level of vibration not only can irritate the driver but also cause them to lift off for fear of damaging the brakes. With the system being developed by Bosch, the intention is to inform the driver by getting the pedal feel to firm up while the vibration pulse, which remains present, is greatly reduced.

Another function that Wienken and his team are working on is continuous current control. “OEM requirements mean that they will not accept sudden voltage drops so we have developed this continuous current control,” says Wienken. “Normally there is a drop in voltage when switching on the pump which in bad conditions can lead to flickering lights. It can also badly affect the accumulator in the car which can suffer from a reduced lifetime. Now we start the pump very smoothly with current controls so there is no sudden drop in voltage. This means no damage to the accumulator and no flickering lights.

“Due to the layout of the ESP Premium,” continues Wienken, “we have a higher system runtime, a higher lifetime endurance that gives us the possibility of having more value-added functions for the end-customer such as touch-activated deceleration. In a normal ESP without any additional functionality, there are five hours of pump-run time during the whole life, which is nothing, but as soon as you start with additional functions then it rapidly increases – and ESP Premium is prepared for that. ESP 8 can get up to 200 hours but ESP Premium can do 400 hours because more functions are activated.

“We can also incorporate a scaleable micro-controller contact and include other software from the OEMs,” claims Wienken. “For example, the ACU normally controls the centre-clutch coupling on a rear-wheel driven car. However, we can implement this software in our ACU meaning that one can be eliminated. The same goes if it’s adaptive cruise control so we can save some space for additional functionality.”

As an addendum to this, we were taken to Bosch’s new winter test centre in North Sweden to drive cars fitted with different ESP iterations, including prototype versions of ESP premium. Despite driving on ice lakes, sometimes with the system on and at other times with it off to demonstrate one’s prowess in driving in difficult conditions, one always felt safe because even a full 360° spin would lead to no harm. However, on arrival back to the UK on a wild and stormy evening, the lack of EPS on your correspondent’s car, something never really considered before, was the cause of real concern when charging down the motorway. It is only when you have first-hand experience like this that the true benefits of ESP become apparent. However, it would be a rather expensive operation for Bosch to ship every driver of the world to northern Sweden to experience the benefits.

 

 


 

 





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