Electronic braking systems are rapidly gaining share in the automotive industry as automakers look to benefits of improved performance at low cost. Matthew Beecham talks with engineers at Bosch, TRW and Continental about their ABS (anti-locking braking system) and ESP (electronic stability programme) technologies.
Although advances in friction materials and caliper designs have helped improve braking performance, the main improvements in braking in recent years have come from electronic control, firstly ABS, then ESP and now brake-by-wire.
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As the world’s largest producer of electronic braking systems, Bosch has played a major role in promoting these developments. In 1978, the company launched the first electronically controlled ABS. Nine years later, Bosch introduced the traction control system. Its next major innovation was the ESP.
While ABS prevents vehicle wheels from locking during braking, and traction control stops the wheels from spinning on acceleration, ESP reduces the risk of skidding in all traffic situations. Although ESP is already standard equipment on many luxury cars, an increasing number of mid-range and small-cars are being fitted with the unit as optional fitment.
Worldwide, nearly 80 per cent of vehicles weighing up to six metric tons have ABS, and more than 40 per cent have ESP. Bosch engineers told us: “We are seeing ABS being replaced by ESP, in part due to legislation and regulations. As more and more hybrid and all-electric vehicles enter the market, brake systems will have to be adapted to the special needs of these cars. This year we will launch our portfolio of regenerative braking systems for these vehicles.”
Continental AG is another major manufacturer of electronic brake systems. Its product portfolio includes electronic brake systems (ABS, TCS and ESC), electronic parking brake systems, brake-by-wire systems, camera-based headlamp control, emergency braking and regenerative brake systems.
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By GlobalDataSteffen Koenig, technical programme manager, Commercial Business Development Electronic Brake Systems, Continental AG, told us: “The major effects we are currently focusing on are all kind of drivetrains, e.g. hybrid and electric cars with new requirements like high efficient recuperation, less or no vacuum, stop and start of the engine in different situations as well as further approaches to reducing CO2. Together with a growing market of comfort and safety functions like as our Automatic Cruise Control, Parking Assistant as well as pre- and post-crash braking, these trends demand high durability and brake performance.
“In addition, modern platforms contain new hardware and software functions without dedicated host systems and small control units. For both, the electronic brake system may offer a flexible integration platform in order to save cost and packaging space.
“In the growing segment of affordable cars, the challenge is [to develop] a brake system that provides all state-of-the-art safety functionality for a suitable price.
TRW Automotive also has a significant share of the global electronic braking system market. In addition to braking systems, TRW’s products include integrated vehicle control and driver assist systems, steering systems, suspension systems, occupant safety systems, electronics, engine parts, fastening systems and aftermarket replacement parts and services.
TRW’s engineers believe that adding further functionality to the overriding building blocks of anti-lock braking, traction control and electronic stability control to enhance safety while reducing size, weight and cost has been a priority for a number of years now. They told us: “As more data has become available regarding accident types and severity – for example, the increase in rollover accidents as higher centre of gravity vehicles entered the market — new strategies such as active rollover management through software were employed. Or when studying the severity of trailering accidents, the need for trailer brake stabilisation became clear.
“More recently, the opportunity to use data from GPS or other infrastructure inputs can allow for features like curve prediction and corner brake control to work hand-in-hand to assist drivers in knowing when to brake and in helping with vehicle control when braking in a turn. There is also a trend toward implementing low speed collision mitigation braking systems combining camera or radar with electronic brake systems to assist the driver at urban speeds.
Another major challenge, says TRW, is alternative powertrain brake solutions. “Unlike the traditional internal combustion engine – direct injection, diesel, hybrid electric and full electric powertrains supply little or no vacuum that can be used to amplify the brake force applied by the driver to actuate the vehicle hydraulic brakes. This requires a different actuation strategy and an electronic brake apply system that can supply high amounts of brake pressure in a short period of time for certain braking scenarios. When the OEM incorporates regenerative braking, the system must blend friction braking with regenerative braking, presenting a further challenge, as these two systems must perform seamlessly to the driver. TRW has developed a Slip Control Boost system in production on GM vehicles such as the new Chevy Volt which has its own hydraulic booster.
As far as the emerging markets are concerned, Bosch engineers see a growing acceptance for these advanced technologies. They told us: “More and more governments are defining clear road safety targets in terms of fatality and injury reduction, and crash avoidance technologies are now acknowledged as being an integral part of a system approach to road safety.”
Wilfried Mehr, head of business development, Advanced Driver Assistance Systems, Passive Safety & ADAS / Chassis & Safety, Continental AG, believes that China will catch-up fast because of the increasing fleet and the resulting increase of serious accidents. “We expect a huge demand for active safety. In other countries with similar market-behaviour it will be the same although demand may rise a little bit slower.”
TRW points out that the Brazilian ABS legislation demonstrates how governments can and will take action to introduce important technologies to the marketplace. They concluded: “TRW’s stance is that all drivers, passengers and other road users deserve to be safe. In emerging markets like China where road safety is a significant and growing issue, it is critical that drivers have advanced technologies and learn how to use or interact with them. A big challenge ahead is not just equipping vehicles properly but changing the mindset of vehicle drivers and other road users in understanding that the rules of the road are very important. TRW has launched and is continuing an effort to teach Chinese children basic safety precepts such as buckling seat belts and how to cross the road safely. The acceptance of technologies and the safe driving mindset will take time but ultimately should prevail.”
