August 22, 2011

New mid-range radar sensors for emergency braking in the middle and compact vehicle classes

In the coming years, driving will become even safer and more comfortable. Bosch is working toward this aim by improving existing assistance and safety systems while at the same time developing new features and improved sensors. "The high number of traffic accidents worldwide demonstrates the need for the best possible safety technology in the car," says Dr. Werner Struth, President of the Bosch Chassis Systems Control division, pointing to the results of a United Nations study. According to the United Nations, each year 1.3 million people die in road accidents worldwide, and some 50 million are injured. The annual number of road deaths could rise to 1.9 million in the next ten years - this increase will mainly be driven by growing traffic density in the emerging countries.

At Bosch, the findings of international accident research form the basis of the company's efforts to develop highly effective assistance and safety features. Skidding is often one of the causes of deadly accidents. ESP® provides a technical solution to this problem. Developed by Bosch, this electronic stability program helps prevent skidding. It went into series production for the first time in 1995, and has since become a mandatory standard feature in a growing number of countries.

Sensors that monitor a vehicle's surroundings and the networking of existing systems already form the basis for high-performing vehicle safety features. The current range of crash-avoidance products is rounded off by radar- ultrasound- and video-based functions such as the predictive emergency braking system, the side view assist, lane departure warning systems, and the night vision system.

In its efforts to develop new safety and assistance features, Bosch has a number of aims. On the one hand, the company is developing innovative products that offer tangible benefits and make driving even safer and more comfortable. In other words, these functions will make drivers’ lives easier. On the other hand, existing systems must become less expensive, as their cost will determine whether they can be employed in low-cost vehicles and in emerging countries. Only if safety technology is widely available can it make the contribution that is needed to injury-free and, ultimately, accident-free driving. Radar technology is one such development.

Smaller radar sensors with improved performance
Radar sensors have an especially long range, and allow distance and speed to be measured exactly. The first generation made by Bosch started off as part of ACC adaptive cruise control in 2000. Compared with this first generation, the current third generation of the long-range radar sensor (LLR3) is an improvement in every respect. Despite being about 60 percent smaller, its performance has been significantly improved. Moreover, the first-ever use of silicon-germanium technology in such a sensor reduces costs significantly. With a range of up to 250 meters and an aperture angle of up to 30 degrees, the LRR3 is the optimum sensor for high-performance ACC systems and predictive emergency braking systems in premium vehicles.

The radar sensor and the ESP® system form the basis of the emergency braking system. If the system detects an impending rear-end collision, it warns drivers and helps them brake. If the collision cannot be prevented, it automatically triggers full braking shortly before impact, making the accident considerably less severe. For dense inner-city traffic, Bosch has expanded the functional scope of the technology – the emergency braking system also supports drivers at speeds under 30 kilometers per hour. This technical solution will go into series production before the end of 2011.

In future, the new Bosch mid-range radar sensor will make such systems even more affordable. The sensor’s maximum range is 160 meters and its maximum aperture angle is 45 degrees. This means that emergency braking systems and ACC solutions can be used at speeds of around 150 kilo­meters per hour – which makes them feasible for use in the middle and compact classes. Installed in the rear, these features make it possible to fully monitor the blind spot. MRR will be launched at the end of 2012.

This new mid-range radar sensor operates like its long-range cousin in the 77 gigahertz frequency bandwidth. It is far superior to the 24 gigahertz variants available in the market, while costing roughly the same. It uses the frequency bandwidth that has been permanently allocated to automotive applications worldwide and is only roughly one-third the size of a typical 24 gigahertz sensor. Moreover, the 77 gigahertz version’s object separation is up to three times more accurate, and can measure speed and distance three to five times more accurately.

Video systems: an ideal supplement for radars
Used with radars, video sensors can provide a range of supplementary information. Merging the two types of sensor data gives rise to a very detailed “image” as an interpretation of the situation ahead of the vehicle. However, doing this calls for comprehensive expertise in all the relevant fields of sensor technology and image processing. The data can be used as the basis for powerful software algorithms.

The video sensor “understands” what is happening around the car. So the data can be used to detect not only vehicles and pedestrians, but also the direction in which they are moving. Moreover, the video data improve the ACC function. Movements across the line of travel can be detected sooner, so the system reacts more quickly, for example, when other vehicles overtake and cut into the driver’s lane ahead. The lane departure warning and lane keeping support features are fully based on video data analyses. Moreover, the video signals can also be used for adaptive light control as well as to detect traffic signals.

Accident prevention: drowsiness detection and motorcycle ABS
The dangerous phenomenon micro-sleep is usually preceded by a typical steering behavior. Bosch drowsiness detection continuously monitors the signals from the steering-angle sensor. If this behavior is detected, the system can warn drivers and urge them to take a break. Drowsiness detection can be produced at a low cost as a software function.

Apart from cars, motorcycles are frequently also involved in accidents. In many cases, the antilock braking system offers an effective remedy. Bosch launched a new, more compact generation in 2010. The basic version of the new ABS generation 9 for motorcycles weighs just 700 grams, which makes it the smallest system available. Its small size and reduced cost allow it to be used even in smaller motorcycles and scooters.

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