Detection system and method for ascertaining an articulation angle between two sub-vehicles of a vehicle, and vehicle combination

A detection system for determining an articulation angle between two sub-vehicles of a vehicle combination connected in an articulated manner includes a detection device configured to detect an environment, wherein the detection device is arranged on one of the sub-vehicles of the vehicle combination and a detection region of the detection device on a sub-region of a sub-vehicle connected to the one sub-vehicle in an articulated manner is oriented so that detection signals, which characterize the sub-region on the other sub-vehicle, can be generated by the detection device and output. The detection system further includes a processing unit configured to receive the detection signals and determine the articulation angle between the two sub-vehicles based on the detection signals and a projection device designed to image a predetermined pattern onto the sub-region on the other sub-vehicle to create a pattern image on the other sub-vehicle.