Worldly ways for Bosch brakes logic

THE export potential of Ford Australia’s new Territory SUV is up for debate but one part of its technical armoury has already been confirmed for international use.

The locally developed software program that controls the way the wagon’s ABS system brakes on gravel roads has been adopted as an international feature by automotive electronics manufacturer Robert Bosch.

The Territory’s gravel road braking logic was developed by Bosch Australia engineers as part of the ESP system that underpins the all-wheel drive version of Territory. Ford calls this system DSC – short for Dynamic Stability Control.

Gaining such a level of international recognition for their wok is a breakthrough, say local Bosch engineers.

In this case their work has been accepted as a part of the ‘main path software’, which means that it is offered worldwide to Bosch divisions including Europe, the US and Japan to adopt as part of ABS systems it is developing for specific vehicles.

A function switch means it can be switched on or off depending on the design parameters of the system being developed. Once switched on, it has to be tuned for the model being developed.

Before its work on Territory, Bosch Australia was limited to parameter modifications of existing software.

But the company was involved in developing the logic for the Territory’s ESP system from day one, with senior systems engineer Chris Woods spending two years in Germany learning the latest Bosch ESP 8.0 system.

The Territory is the first Australian manufactured vehicle and the first in the Ford world to employ ESP 8.0. Bosch is the only local manufacturer of such systems and supplies ABS and traction control to all four local car manufacturers.

Mr Woods developed the unique gravel road logic with senior applications engineer Carl Liersch, who has headed up the Bosch work with Ford on Territory for the past two years.

Mr Liersch and Mr Woods came to be convinced during the development program that Bosch’s existing ABS logic for gravel roads was not suited to Australian conditions.

"It’s been a well known and long known issue that ABS has a deficiency on gravel – that it doesn't stop as well on gravel," said Mr Woods.

"We took that on board and tried to develop something that really suited the Australian environment.

"The existing gravel logic that was around wasn’t suited for gravel in Australian conditions. It really looked for big chunky gravel and rocks all over the surface and wheel oscillations.

"It doesn’t work in Australia where you have perfectly smooth and flat roads with a clay base and you don’t pick up any oscillations in the wheels whatsoever.

"So based on that we used a new estimation in our system to determine we were on gravel and then we increased the target tyre slip from around 10 per cent to 40 per cent."Tyre slip is the percentage difference in speed between the car body and tyre when braking. If the vehicle is travelling at 100km/h and the tyre at 90km/h, the slip is 10 per cent. If the body is travelling at 100km/h and the tyre at 60km/h, it is 40 per cent.

"The fear for many years has been that if you have too much slip you lose your steering ability and stability," Mr Liersch said.

"But we have taken the chance, gone out and given the vehicle 30 to 40 per cent slip on gravel and we have shown you can still steer the thing and have stability in those conditions.

"And there are conditions on a wet asphalt road going down hill where we detect a similar friction level and so we do give more slip under those conditions."Cleverly, the target slip is decreased if the ESP system detectes via the steering wheel angle sensor that the car is turning, aiding steering and stability.

Mr Liersch said the Australian-developed gravel road logic would be a respect generator rather than a revenue raiser.

"It’s a recognition that we can cut it with the rest of the world and we do it as well as anyone else in the world – and recognise our own situations and we can adapt to those things," he said.