Filo Concept Car Demonstrates By-Wire

The Filo concept car is a reminder that while today's vehicles are still controlled via mechanical/hydraulic linkages, a potent competitor is emerging-drive-by-wire. Conceptualized jointly by SKF AB, Gteberg, Sweden, and Italy's automobile designer Bertone, the Filo (Italian for wire) dramatizes the disruptive potential of the by-wire idea. By implementing by-wire's electronic link to the running gear, the developers also gained the opportunity to re-evaluate the human-machine interface. The result: By-wire enabled new styling freedom for the Filo's interior. A decades old control solution for aircraft, the by-wire concept can offer weight reduction, lower manufacturing cost and the opportunity to introduce electronic control via mechatronics, says Filippo Zingariello, vice president for SKF's Drive-By-Wire Business Unit, Turin, Italy. He's charged with extending SKF's success in marketing fly-by-wire to automotive applications. With the Filo, driver input (steering, acceleration, braking and gear shifting) is translated into electrical signals that go by wire to electromechanical control units. Electric motors take over the conventional mechanical or hydraulic functions with integrated sensors and measurement systems determining position, force and displacement. The electronic logic between the actuators and driver controls offers vehicle designers an easier way of making the vehicle's "feel" programmable to suit different drivers. By-wire technology is also a boon to interior styling because there are fewer constraints on the driver interface, making it easy to depart from the conventions of steering wheels and columns, brake pedals, etc. (A recent DaimlerChrysler by-wire concept car was shown with a joy stick.) The Filo's operator interface takes a somewhat more traditional approach with its Guida-Filo (driver control unit) mounted on the front seat's center armrest. Steering is still based on turning the control unit, but putting a full lock on the wheels requires only 20 degrees of movement versus one-and-a-half turns on conventional cars. Instead of floor-mounted brake, clutch and accelerator pedals, the Guido-Filo puts those controls on the handgrips. Zingariello says mounting the Guida-Filo on the front seat's center armrest also simplifies one export consideration. "Adapting the vehicle from left-hand to right-hand drive (or vice versa) is reduced to modifying the mounting bracket for the Guida-Filo. He expects automakers to adopt the technology incrementally with the first SKF system, by-wire braking, appearing on vehicles in the 2003 model year. Don't expect anything as comprehensive as the Filo until 2010 when 42-volt electrical systems will be available to support the increased electrical load, he adds. Also launching in 2003 are first-generation brake-by-wire systems from TRW Chassis Systems, Livonia, Mich. In this initial phase, brake-by-wire will complement today's hydraulic braking systems, says Thomas Straub, technical director, Advance Vehicle Controls. TRW expects systems without hydraulic backup will not appear until 2005. He notes that by-wire technology makes it essential that suppliers have expertise in electronics and software in addition to braking mechanics.