Parking sensors

When parking assistance devices or systems are referred to, which are particularly in confined spaces facilitate the parking of a motor vehicle.

Passive systems

For the passive systems include orientation points on the vehicle or the parking lot, which the orientation, specifically facilitate the recognition of the vehicle position. In previous truck, for example, the front bumper or the front fenders were often attached flexible side markers, the tip of the driver could use as a guide at the ends. The ends of the vehicle itself, he could not see out of the cab. In the Mercedes -Benz S- Class of 1991 were due to the unusually large for cars vehicle dimensions dipsticks installed, which were sunk in the rear fender, and exports about eight inches in engaging reverse gear.

In the 1960s, large-sized luxury vehicles (especially Cadillac and Mercedes -Benz ), the famous tail fins integrated into the design, which served also as points on the rear of the vehicle.

Since the 1950s, so-called Curb feeler (English curb probe) were used. This sensing rods were either 15 to 30 inches horizontally from the sills in front of the front wheel arch from, or rose from the front end of the front wheel arch about 35 inches diagonally downwards. They generated when approaching a curb a scratchy sound, which warned the driver of another approach.

Active systems

There are currently two methods of measurement that are used in vehicles. Regardless of the measurement method of the driver is shown as either purely acoustically or optically and acoustically, the distance depending on the manufacturer and scope. The purely acoustic version signaled by increasingly rapid until the tone sounds warning distance. Opto- acoustic systems first show on LEDs or a graphic on the screen visually approaching an obstacle and alert you to a very small distance (about 30 cm or less), an acoustic with fast beeps until time warning against the "danger ". In addition, there are systems that perform all the required maneuvers autonomously.

Ultrasound -based Systems

These systems operate with ultrasonic sensors that are integrated into the bumper of a vehicle. We distinguish between two-, four -and six -channel systems, which means that the bumper 2, 4 or 6 round, usually color-keyed sensors are installed. The following applies: The higher the number of sensors, the more accurate and reliable measurement results, the width of the vehicle is crucial for the required number of sensors. Send this sensors and receive ultrasonic signals and transmit the data obtained to the control unit, which then calculates the distance from the sensor to the obstacle from the ultrasonic signal transit time.

The first functioning ultrasonic parking aid was brought in 1982 in the middle class sedan Toyota Corona in its home market of Japan, under the name back sonar for the market. Many car manufacturers conduct their own names for their parking systems such as APS (acoustic parking system ) at Audi, PDC (Park Distance Control) at BMW, PARKTRONIC with Mercedes-Benz or park pilot at Volkswagen. The system is now being applied up to a speed of 20 km / h and for measuring the distance to the vehicle ahead and serves as the prevention of rear-end collisions. Can be disturbed by other Ultraschalleinparkhilfen ultrasound sources such as compressed air brakes of trucks and buses or jackhammers. Ultraschalleinparkhilfen is also available for retrofitting.

Radar - based systems

A radar-based parking aid was first made ​​possible by a short-range millimeter-wave radar. The measuring method is the same as the ultrasonic embodiment, but here, radar signals are evaluated. The advantage is the elimination of additional ultrasonic sensors in the bumpers, which in turn brings the following benefits:

• Costs, technology costs and saves weight, since all necessary components " are made available " to the distance control system
• There are no visible sensors more, since the millimeter-wave radar measures by the bumper round
• It is warned in time with faster reverse mode before more distant obstacles
• The radar measuring system is sensitive to ultrasound sources

A drawback occurs in very heavy rain, if the radar sensors occasionally warn of runoff water on the bumper.

Self-steering systems

In addition to the indication of the distance there are so -called park steering assistant, which completely take the necessary steering during parking maneuvers. This is based on an active parking assistance as described above and in addition by an electric motor-driven electro -mechanical power steering and a transversely oriented to the direction of measurement sensors. Some systems also require a reversing camera to make choose the parking space in front of the parking maneuver by the driver on the camera image shown on the screen.

After the system is activated by pressing a button or drop below a certain speed sensors measured transversely to the direction of travel and during pass the parking space. Is this big enough, this is indicated to the driver. The driver now has a certain distance to the parking space to stop, shift into reverse and only gently on the gas with respect to the traffic situation. The steering assistant takes over the One - and counter-steering into the parking space now complete. If the minimum distance reached backwards, the driver must bring the vehicle to a stop, shift into forward gear and now even set depending on the installed system the car forward or continue to just push the accelerator and brake. Modern systems dominate repeatedly correcting the position in the parking space. The required maneuvers are calculated using Klothoidenbahnen with a constant angular path. Since the driver still pressed the accelerator and brake pedals, it remains the responsibility themselves.

Camera - based systems

A further possibility to facilitate the parking of the use of rear-view cameras. These are located at the rear of the vehicle and capture your surroundings behind the car. Switch on when reverse gear is engaged and show her picture on a display in the cockpit. Not necessarily they must work together with a distance measuring system. Different colored guide lines on the display represent the value specified by the steering wheel way or the area directly behind the car dar. Additional features can a zoom mode to the trailer hitch area or a mode for parallel parking be. An advantage of this camera is that even very low obstacles can be performed that would not detect the parking sensors.

As an extension to exist so-called surround view systems which generate an image from a bird's perspective, ie from the top of the vehicle. These are located next to a reversing camera more wide-angle cameras on the front and the two exterior mirrors. All images are to digitally rectified and displayed on a monitor in the cockpit. For the first time this Around View Monitor system referred to came in late October 2007 in the Japanese Nissan Elgrand on the market. Such systems are offered among others by BMW (Surround View) and Volkswagen ( Area View ). Lexus has also developed a simpler system with a camera at the right hand mirror, filming the poor visibility for the driver's right side of the vehicle. She also works with angeklapptem levels and helps especially while avoiding curb contacts. As a function of the Surround View, BMW two Side View cameras come in the front fenders are used, which are primarily used for observation of cross traffic at blind spots.