Ko-TAG

Ko-TAG is a collaborative research project exploring cooperative radio-based sensing technology. Most of the work is aimed at applications such as protection of vulnerable road users and vehicle-to-vehicle safety.

The aim of the overarching Ko-FAS research initiative is to make significant contributions to improving road safety, i.e. to reduce the frequency of accidents and mitigate their consequences as far as possible. It is in this context that the Ko-TAG project investigates cooperative sensing based on transponder systems.

In cooperation with partners of the project Ko-TAG the Fraunhofer researchers received the award for mobility of the ADAC in Bavaria on October 2nd, 2013.

Ko-TAG and Ko-FAS are being undertaken in collaboration with project partners from the automotive industry and sponsored by the German Federal Ministry of Economics and Technology.

Based on cooperative sensing technology, the pedestrian protection system detects, identifies, locates and tracks pedestrians. It is specially designed to deal with situations where there is no line of sight. Vulnerable road users such as pedestrians or cyclists are equipped with active transmitters. These can be embedded in clothes, satchels or cell phones.

The tracking technology incorporated into the vehicle uses a multiple-antenna system to identify pedestrians and cyclists based on active transmitters worn or carried by them. If a pedestrian is close to the car, they will be reliably identified as a vulnerable road user. The system then determines how far away the mobile transmitter (and hence the pedestrian) is and in which direction. If there is a risk of collision, the system will either warn the driver or take action to avoid or mitigate it. This is possible even if the pedestrian is obscured by parked cars or buses.

The pedestrian protection system integrated into Ko-TAG starts by tracking all pedestrians in its sensing range who are equipped with a transponder system. A multiple-antenna system incorporated into the vehicle measures the distance to each object tracked and the angle it forms with the vehicle. The tracking system will stay connected to a transmitter even if there is no line of sight.

Apart from on-board angle and distance measurement, the tracking system also uses an inertial measurement unit, which is integrated into the transceiver and acquires data on the pedestrian's speed and direction. The information collected is fed into the tracking process, helping refine results.

Another advantage of the integrated inertial measurement unit is that it allows the transponder system to be deactivated whenever it has been stationary for a long period of time. This means that the transceiver unit can be switched off to minimize power consumption.

The ability to track pedestrians obscured from view provides a basis for adding further capability through data fusion, e.g. using input from video-based image processing. Since the tracked path of the pedestrian is sufficient to predict exactly where they will step into the road even if they cannot yet be seen, an area of interest can be defined within the image and specially processed. This area can then be closely scanned for shapes or even partial shapes (e.g. legs, chest or head) of pedestrians.

Ko-TAG can thus generate valuable additional information for image-based pedestrian detection. Combining the two approaches will ensure reliable identification of pedestrians and yield very high quality data on their lateral and longitudinal distance. This will form the basis for a range of protective measures, including an automatic emergency stop.

Once the system has detected a pedestrian and tracking has yielded position and velocity information, the risk of colliding with the pedestrian can be calculated. This is a complex process because both the pedestrian and the driver may act in a variety of ways, which means a collision is impossible to predict with absolute certainty until it is imminent.

As a rule, however, the protection system will need to take action much earlier if it is to be able to limit the severity of a potential accident. This requires the ability to accurately identify and assess the pedestrian's range of possible behaviors, as pedestrians are more maneuverable than vehicles and can change direction very quickly.

The pedestrian's behavior is predicted with the aid of a statistically based behavior model. This method involves first deriving a model of the pedestrian's behavior from previous observation of a large number of pedestrians and then determining his or her most likely behavior in a given situation.

Based on the general mechanics of human locomotion and on observed behavior, it is possible to identify patterns that typically precede specific changes in a person's movements, indicating, for instance, that they are likely to step into the road. In the case of Ko-TAG, a combination of early indicators derived by tracking the pedestrian's movements and information from the inertial measurement unit is used to predict a hazardous change in the pedestrian's behavior.

If the collision probability exceeds a threshold, the amount of time remaining until contact with the pedestrian (also known as time to collision or TTC) is calculated on board the car. Depending on how much time remains as well as on the speed of the vehicle and the specific situation encountered, the planned demonstration system will initiate a particular type of intervention.

If the time to collision exceeds 1.5 seconds, the driver will still be able to respond effectively to a warning. Additionally, the system can prepare the vehicle for an emergency stop by precharging the brakes and optimizing brake force distribution.

If a collision is very likely to be unavoidable, the system can initiate an emergency stop. In addition to actuating the brakes, it can optimally prepare the vehicle's occupants for the emergency stop by activating the belt pretensioners and head rests (source: http://ko-fas.de/).

An obvious way of extending the usefulness of the Ko-TAG system is to enlarge the safety zone in front of the vehicle by enabling detection not only of pedestrians and other vulnerable road users but of all types of road users. The ability to locate vehicles equipped with transponders would create a unique opportunity to identify hazards that conventional sensing technology is unable to detect.

One example is an imminent side crash at a four-way intersection or a three-way intersection with very poor visibility. In such contexts, maximum benefit can be derived from the Ko-TAG system's ability to detect and track objects obscured from view and to precisely locate a collision partner prior to impact. By factoring in simultaneously communicated data on the dimensions and current speeds of the vehicles concerned, it becomes possible to determine potential collision paths more precisely than is possible with current (cooperative or self-contained) technologies. As a result, drivers could be warned of a possible collision early enough to be able to avoid it.

An omnidirectional version of the Ko-TAG protection system will make it possible to address situations such as head-on, rear-end and side crashes and possibly skidding accidents. It may also enable applications such as blind spot and intersection assistants.

The pedestrian protection system will serve as a basis for the omnidirectional system, with existing features retained and added to. This latter system will identify not only pedestrians and cyclists, but also motorized vehicles such as cars, trucks and motorcycles, which all have specific movement characteristics. To this end, appropriate motion models need to developed that make it possible to calculate potential collision paths and to derive the necessary trigger algorithms (source: http://ko-fas.de/).

Fraunhofer IIS's ideas help equip cars with high-performance electronics. Vehicles fitted with these technologies are in tune with the environmental concepts of tomorrow and offer drivers, passengers and other road users greater safety. For the automotive industry, this in turn translates into progress and competitiveness.

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