Development work is ongoing, but tire makers and chassis suppliers say they've been able to make vehicles safer by working together.
Sharing data during development makes for more robust modeling capabilities, improves the inherent safety of tires and the chassis system, decreases stopping distance and lessens the chance of vehicle rollovers by providing more stability, these auto industry participants contend.
Meanwhile, all but one of four major automotive suppliers of partial or complete chassis systems also maintain there is value in integrating the workings of tire and steering, suspension and braking systems.
Tires are the only part of the vehicle that touches the road, said Tom Chubb, vice president of marketing for Michelin Automotive Industries Division (MAID), the original equipment unit of Michelin North America Inc. The better tire and chassis systems are ``married together,'' the more secure and responsive the vehicle will be, he said. More than a year ago, Continental A.G., the pioneer in tire-chassis integration, was able to combine all of its systems offerings to create the 30-meter car, which boasts significantly reduced stopping distance. Continental created the project ``to prove to the public that we could significantly improve safety'' and develop and manufacture the parts needed to do it in-house, said Andreas Gerstenberger, vice president of sales and marketing at Continental Tire North America's P/LT replacement tire business unit.
The 30-meter car (designed to reduce the 35-0 mph braking distance to 30 meters, or 97.5 feet) was an experiment, but Continental has practical applications of its tire and chassis integration as well. The new Ford Expedition and Lincoln Navigator are equipped with tires, foundation brakes and electronic braking controls from Continental.
``We are heading for total control and chassis management,'' Mr. Gerstenberger said. ``It's not a single component; we are looking at the total system, with something like a brain,'' to attain a certain level of optimized system control.
Continental acquired its electronic thinking capabilities two years ago when it purchased the former Temic unit of DaimlerChrysler A.G.
Integrating the systems by developing them together and having them function together makes a vehicle safer by keeping it under the driver's control and on the road, said Robert Arguelles, chief engineer of electronic brake systems at Continental Teves North America, as the former DaimlerChrysler unit was renamed after the acquisition.
``We have more and more (auto makers) coming to us with requests for total chassis system solutions,'' Mr. Gerstenberger said.
Meanwhile, TRW Automotive Inc. and Goodyear teamed up in March to jointly develop integrated tires, suspension, braking and steering systems in the interests of shortening development time and improving overall vehicle safety.
They are starting off by developing a virtual vehicle model to gauge the interaction of the chassis and tire systems, said Phil Cunningham, director of product planning for chassis systems at TRW, and they will add functions to the model as they seem relevant.
``Our hypothesis is that if we can make a vehicle more stable, when it loses control it's less likely to leave the road and roll over,'' he said. The two companies also believe they can reduce stopping distance and make the inherent performance of the tires and braking system better in their own right.
Goodyear and TRW are looking for improved handling in a number of situations, including emergencies where the driver loses control of the vehicle. By integrating tire, stability control and suspension data, the two expect to better stabilize the vehicle in blowout or underinflated conditions, Mr. Cunningham said.
Now that tire pressure monitoring systems are becoming more prevalent, ``we are likely to be able to use that data and take it into consideration in our algorithms,'' he said. ``The more we know in terms of actual data, the (fewer) assumptions we have to make. The more information we have, the more we are able to refine the performance of the vehicle stability control system.
``It's early in the joint work, but we do see from the data that we have currently gathered that vehicle stability control could have a significant impact on reducing rollovers,'' Mr. Cunningham said,
Robert Bosch GmbH and Group Michelin are taking a more specific look at how vehicle stability control systems, by controlling the lateral forces of the vehicle, can reduce instability brought on by sudden maneuvers in the ``flat tire'' mode.
``The benefits there are very clear and easily demonstrated,'' said Bob Rivard, vice president of advanced technology at Bosch.
Also, by optimizing the slip angle on the road using the stability control, you can either drive faster or drive a longer distance in the run-flat mode than otherwise recommended, said Rich Golitko, marketing director of electronic stability control systems at Bosch.
The collaboration between the two companies through a joint venture established in the fall of 2001 is taking place in Drancey, France, and is centered on improving the performance of Michelin's Pax extended-mobility tire/wheel system with Bosch's electronic stability control system, Mr. Rivard said.
It's too early to speculate about adding a steering component to the virtual model Bosch is creating with Michelin, but the German company already has a joint venture for steering systems with ZF Group, separate of the pact with Michelin, Mr. Rivard said.
Michelin said it is involved in tire-chassis integration work that's slated for production but would not give details.
Like Continental, Delphi Corp. feels it has a competitive advantage, thanks to its in-house system capabilities. Delphi has an electronic stability control program called Traxxar, is developing electric hybrid braking, electric steering, active suspension and has internally developed electronic controls capability.
In collaboration with General Motors Corp., Delphi integrated its steering, braking and active suspension systems for the 50th anniversary Corvette launched this year.
Another possibility for the future is using data from a ``smart tire'' to transmit certain characteristics to the braking system. The braking system can use that data to enter certain criteria-type of tire, inflation pressure, age or wear of the tire-into its algorithms and calibration of the vehicle. It can then better respond to driver actions, Bosch's Mr. Rivard said.
``Those are the concepts that all of the inventors of stability systems would like to have,'' he said.
Continental has its ``Intelligent Tire'' concept, while Michelin and Goodyear both have embedded tire pressure monitoring systems, which are the basis for the more advanced data transmission to the braking systems, Mr. Rivard, said.