Video-based Trailer Detection and Articulation Estimation

Even for experienced drivers handling a roll trailer with a passenger car is a difficult and often tedious task. Moreover, the driver needs to keep track of the trailer's driving stability on unsteady roads. There are driver assistance systems that can simplify trajectory planning and observe the oscillation amplitude, but they require additional hardware. In this paper, we present a method for trailer detection and articulation angle measurement based on video data from a rear end wide-angle camera. It consists of two stages: to decide whether or not a trailer is coupled to the vehicle and to estimate its articulation angle. These calculations work on single video frames. The vehicle is therefore not required to be in motion. However, we stabilize the single frame estimations by temporal integration. We perform training and parameter optimization and evaluate the accuracy of our approach by comparing the results to those of an articulation measurement unit attached to a test vehicle's hitch. Results show that it can very reliably be determined whether or not a trailer is coupled to the vehicle. Furthermore, its articulation can be estimated with a mean error of less than two degrees.