For a couple of years, advanced driver assistance systems (ADAS) have been known from high-end passenger cars. They have been adapted for trucks and other heavy-duty vehicles. Besides dedicated data provided by radar sensors and cameras, many of these systems use information from the CAN-based in-vehicle networks. In some applications, the ADAS actions are forwarded into the CAN networks, for example to brake the truck or to accelerate the speed.
FOR A COUPLE OF YEARS, advanced driver assistance systems (ADAS) have been known from high-end passenger cars. They have been adapted for trucks and other heavy-duty vehicles. Besides dedicated data provided by radar sensors and cameras, many of these systems use information from the CAN-based in-vehicle networks. In some applications, the ADAS actions are forwarded into the CAN networks, for example to brake the truck or to accelerate the speed. Truck traffic is increasing and safety is becoming more important. Ninety percent of the accidents are caused by driver error. In order to handle difficult traffic situations in the future, the truck makers, suppliers, and independent researcher are working to make vehicles smarter than before, helping the driver to avoid potentially dangerous situations. Today's advanced driver assistance systems (ADAS) include, for example, warning systems and driver awareness support. In most cases, the driver is simply warned when something is wrong.
The next step in safety is to improve the electronic systems, so that they can assist the driver in avoiding a crash. They support the trucker in driving the vehicle, for example in dangerous situations.
At the IAA exhibition in Hanover (Germany), Knorr-Bremse (Germany) showed camera and assistance systems from its North American subsidiary Bendix, in the shape of AutoVue and SafetyDirect. The AutoVue system warns when departing the lane. The SafetyDirect is a kind of "black box" that records vehicle data not continuously but only in critical situations. The data acquired can be used for driver training purposes as well as providing a source of information following an accident. Through the use of smart environment sensor systems based on advanced radar and video technology, the functionalities of the EBS and ABS brake control systems can be substantially expanded in the context of driver assistance systems.
Advanced emergency braking system
At the IAA fair, Daimler received for its Actros and Antos trucks the certificate for the AEBS (advanced emergency braking systems) by the German Federal Motor Transport Authority (KBA). This was the first certificate of approval to be issued in Europe in relation to the international regulation. The mentioned trucks were proven to meet the legal requirements that will in fact not become mandatory until the second stage of the Regulation takes effect in 2018. The Mercedes-Benz Actros equipped with the ABA 3 third-generation emergency braking system initiate full autonomous braking in situations involving stationary obstacles. The truck is thus able not only to mitigate the consequences of rear-end collisions, as hitherto, but also to prevent such accidents from happening in the first place. Driver assistance systems can play a significant role in the prevention of road traffic accidents. In 2009, the EU Commission, under its general safety Regulation 661/2009/EC, initiated a series of measures aimed at improving road traffic safety. This prescribes the phased mandatory introduction of three important driver assistance systems with relevance to road safety for all new vehicles throughout Europe:
AEBS systems are designed to identify automatically an emergency situation and to alert the driver to take appropriate braking or steering action himself in order to prevent an accident or, in the event that the driver does not react, to activate the vehicle's braking system in order to avoid an accident or minimize its consequences. The adaptive cruise control (ACC) and emergency braking systems (EBS) that are currently available on the market are able to recognize and react to moving targets, in other words to vehicles driving or slowing down ahead. The IAA 2012 saw the introduction of the ABA 3 system, which is now also effective in situations involving stationary obstacles such as construction site safety vehicles or vehicles that have broken down, and to take the initiative to brake the vehicle to a standstill and so completely prevent a rear-end collision. Such systems have a significant part to play in reducing accidents in the way that they help inattentive drivers to recognize critical situations and are able to reduce kinetic energy through autonomous braking. By the way, Actros trucks implement twelve CAN networks with more than 30 electronic control units (ECU) running at 500 kbit/s or 667 kbit/s. Some of them are connected to the AEBS system. The increasing bandwidth requirements makes Daimler’s engineer interested in the CAN FD protocol, which allows higher bit-rates and provides optionally longer data fields. The company presented its first evaluation results during the CAN FD TechDay in Detroit last year. The next CAN FD TechDay will be organized by CAN in Automation (CiA) in Frankfurt (19 March 2013). Bosch, Daimler, and NXP will present their CAN FD bridge featuring one classic CAN port and two improved CAN interfaces supporting the CAN FD protocol.
In Europe, EVSC systems are mandatory for heavy commercial vehicles since November 2011. Knorr-Bremse (Germany) and Wabco (Germany) are the major suppliers. Wabco sold more than 50 000 units. The brake-maker also provides AEBS solutions. The OnGuardMax system reacts to moving and stopped vehicles. The company also supplies an ACC system with active braking, a collision mitigation system (OnGuard), and an autonomous emergency braking system on moving and decelerating vehicles (OnGuardPlus). Wabco’s ACC system is specially designed for commercial vehicles. It allows the driver to not only control the vehicle speed, but also to adapt the speed of the vehicle. If the vehicle in the same lane in front of the truck slows down, the system will automatically adjust the speed of the truck in order to maintain a safe distance. The OnGuardMax system helps to reduce risks of colliding with moving or stopped vehicles by providing a multi-level warning concept and automatically actuating autonomous braking. Rear-end collisions are among the most frequent types of accidents experienced by commercial vehicles.
The EBS 7 electronic braking system by Knorr-Bremse goes into volume production beginning of this year. One key advantage of this system is that it is installed outside the cab on the vehicle frame. This has several benefits – not only in the cab, where space is at a premium, but also in terms of wiring, because there are in any case multiple connections located around the frame. The system combines the company’s anti-lock braking system (ABS), anti-slip regulation (ASR), and EABS. Another advantage of this electronic system compared to ABS alone is the shorter response time, leading to a further reduction in stopping distances. Knorr-Bremse’s focus on improved safety is not limited to tractor vehicles but also extends to semitrailers and trailers. The company’s TEBS unit for trailers brings together electronic controls, pneumatics and sensors in a single unit.
It offers extended functionalities through the integration of electronic leveling control (ELC). The use of a second, trailer-based CAN network makes for a significant reduction in system complexity in the trailer. The recently introduced ST7-430 trailer brake from Knorr-Bremse is a two-piston disc brake for 22,5-inch wheels. It is designed for 9-ton trailer axles. Due to its optimized disc and caliper it weighs around five kilogram less than its predecessor, thereby boosting efficiency in the trailer.
Lane departure warning systems
LDWS will become mandatory for trucks on European roads and highways end of this year. Truck-OEMs are prepared: Scania’s LDWS takes into account the driver’s behavior as well as adverse weather conditions. This smart system warns the driver if the vehicle unintentionally crosses lane markings on the road. A series of features reduce the risk of false alerts. In addition, the system monitors steering wheel movements in a way that allows it to detect active steering input as opposed to inattention. Volvo engineers are looking into the possibility of having the truck help the driver to avoid lane change accidents by giving full lateral support. This implies an active steering by the electronics. In combination with an electric intervention in the steering LDWS becomes an active lane-keeping assistant. A smooth recommendation in the steering is an additional warning to the driver, but the driver’s decision takes priority at all times. Through these system interventions important seconds could be gained, which can save lives, especially when at the edge of the verge.
On the way to the driverless truck
In the next years, trucks will be equipped increasingly with ADAS equipment in order to meet the safety requirements and to reduce fuel consumption. The truck collects data from other vehicles, from the roadside and via satellite as well as from the in-vehicle networks, of course. There are in-vehicle sensors producing more data than CAN networks are able to transmit. For them Ethernet could be a solution. But CAN is and will be the dominating in-vehicle network in trucks and other heavy-duty vehicles. Future ADAS solutions will not just inform and warn the driver, but will actively brake, steer, or drive the truck. We are on the way to the driverless truck.
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