Tony Rendi, Ford's manager of brake development, hints at other creative uses of electronic stability technology moving forward. "We will continue to build upon the new architecture," says Rendi. "You'll see new features similar to trailer sway that can be built off the architecture that you now have in the vehicle."
Automakers have been using on-board sensors to control brakes since the 1980s, when anti-lock braking systems (ABS) first became available. Today's ABS systems use speed sensors on the wheels to determine the braking force needed for each wheel, which can be individually controlled. ESC adds a control unit that monitors steering wheel angle and vehicle rotation around the vehicle's vertical axis. In combination with the ABS components, those sensors enable the ESC system to detect when a vehicle is about to skid and to apply brakes to the appropriate wheel to help the driver maintain control.ABS systems also continue to be refined. Chrysler, for example, has developed new algorithms for its ABS systems to support capabilities such as brake locking differential (BLD), now available on most models, and electronic brake distribution (EBD). As Chrysler spokesman Nick Cappa explains, BLD has the functionality of a mechanical limited slip differential without the cost, "If you spin up one wheel, the brakes gradually apply to transfer torque to the other drive wheels," explains Cappa. EBD, Cappa explains, has eliminated the mechanical brake proportioning valve from the system, using an algorithm to automatically compensate for different vehicle loadings and for the amount of traction available.
Some automakers use inputs from other on-board systems to enhance braking system capabilities. BMW, for example, uses rain-sensing technology built into its windshield wipers to periodically bring the brake pads into light contact with the brake rotors to eliminate any water on rotor surfaces.Another advanced braking capability is Adaptive Cruise Control (ACC), which uses radar as an input to braking controls. As Martin Hogan, director of brake controls for GM explains, "ACC uses radar to determine the relative position of the object in the front and commands automatic braking to maintain a set gap." ACC is currently available on some luxury General Motors vehicles and on the Lincoln MKS. "Future enhancements to the automatic braking system will enable higher braking forces, which will minimize forward or rearward collision severity," Hogan says.
Radar also underlies collision mitigation with braking, a capability that Ford plans to launch soon. "It will monitor for collision threat and can help decelerate the vehicle in response to a collision threat," explains Rendi. "It won't prevent an accident but just taking some speed off can significantly improve a crash situation."
Some future brake system capabilities will be based on the concept of state definition, which compares how a vehicle is behaving with how the driver wants it to behave, Rendi explains. He points to the example of park assist, which would make necessary corrections to help drivers in parking their vehicles.
True electronic brake technology, like that in brake-by-wire systems, is being leveraged. Some of the earliest applications of electronic braking technology are likely to involve parking brakes. Cappa notes, "Electronic parking brakes show promise for improving complexity, weight and security of the parking brake system, which is largely separate from the rest of the vehicle's braking system."
Ford of Europe already offers electronically actuated parking brakes and a key advantage is that they can free up extra space in the front compartment, Rendi said.
As electric and hybrid-electric vehicles become more popular, we'll also be hearing more about regenerative braking systems, which are unique to those types of vehicles. "Regenerative braking converts kinetic energy during coast down or braking into electrical energy, allowing it to be stored in a battery," explains Hogan. Once stored in the battery, the energy can be used to drive the vehicle's electric motor during acceleration. "This reduces the amount of work the internal combustion engine has to do and saves fuel," Hogan says. GM, Ford and Honda offer regenerative braking on their hybrids, and Chrysler will join the ranks shortly with a Dodge Ram hybrid.
"If you can recapture energy that would normally be lost and store it in a battery for later use during acceleration, it will greatly improve fuel economy, reduce emissions and improve friction brake life," Cappa says.
Automakers also continue to make incremental gains in traditional hydraulic braking technology. "Brake suppliers have been pushing electric solenoid actuated calipers as the next advancement from hydraulic brakes for a number of years," Cappa says. "The technology has progressed to a reliable and cost-effective possibility in the future."
GM is working on lower drag calipers for improved fuel economy and lightweight/ higher performance calipers for improved fuel economy and improved pedal feel, Hogan says. In addition the company has introduced ferritic nitro-carburizing (FNC) brake rotors on the 2009 Cadillac DTS. FNC is a "thermo-chemical diffusion process that puts nitrogen and carbon into the rotor surface to improve rotor corrosion performance," Hogan says. The added corrosion protection results in better performance for brake pulsation, he said.
An important focus for GM is global component design. "Common parts are being developed for use on multiple architectures and applications," says Hogan.
Ford, meanwhile, has set the goal of gaining a high level of recommendations from Consumer Reports. "It's a driving goal for a lot of our daily work," comments Rendi. "There's a lot of emphasis on stopping distance. They also do accident avoidance testing — and they continue to raise the bar."
