Evaluation of parking assist systems

Parking assist systems or aids are intended to contribute towards active safety and also to make it easier to maneuver into and out of parking spaces. Parking aids range from purely informative systems (parking beepers or a camera) to fully automatic parking systems. In previous UDV trials with test subjects it was found that even simple parking aids deliver good results in certain vehicles. Until now, however, it has been unclear to what extent this can be generalized.

In a new project three different vehicles were used with the parking assist systems rated highly in the preliminary UDV study. The vehicles varied in terms of the visibility they offered. The driving trials were carried out with 60 test subjects. The following parking assist systems were used: audible alerts at the front/back, a generic multiview camera system, a parking steering assist system with a reversing camera and a fully automatic parking system with an additional reversing camera.

The comparison of vehicles with and without assistance shows that parking assist systems can generally reduce the number of collisions. The fewest collisions occurred when drivers reversed into parking spaces. In contrast, many collisions occurred when they reversed out of parking spaces. Often they collided with something that appeared suddenly. A rear area monitoring system with automatic emergency brake function for reversing out of parking spaces should therefore be integrated in parking assist systems.

Cameras can be helpful when parking in tight spaces. When two vehicles of different sizes were compared directly, however, it became clear that cameras are not a universal panacea. Both vehicles were involved in numerous bumps during parking, particularly when maneuvering in tight spaces. This happened more often with the larger vehicle than the smaller one. This problem can be mitigated to a certain extent with a top-view system. The driver is able to understand the information provided by a top-view system more easily than when it is provided in the form of camera images.

As far as the kind of automation is concerned, all drivers were able to avoid parking collisions only when the system with automatic longitudinal and lateral control was used. However, the problems when leaving parking spaces remain.

The combination of longitudinal control by the driver (acceleration, braking) and lateral control by the system (steer-

ing) is not ideal, and one problem with this semi-automatic system becomes clear: the distance-dependent triggering of the warning. If the driver enters the parking space relatively quickly, the distance-dependent warning may come too late. A warning strategy taking into account the speed driven could eliminate this weakness of existing parking assist systems.