A METHOD FOR DETERMINING HYDRAULIC FAILURE IN A HYBRID STEERING SYSTEM, A CONTROL DEVICE, A HYBRID STEERING SYSTEM AND A VEHICLE

摘要

The present invention relates to a method for determining hydraulic failure of a hybrid steering system (10) during automated operation of a vehicle (1), said hybrid steering system (10) comprising: a steering column (SC) connected to a wheel axle (X) with steerable wheels (W); an electric power steering system (EPS) connected to the steering column (CS); and a hydraulic power steering system (HRS) connected to the electric power steering system (EPS), the method comprising: determining (s101 ) a target steering angle change (Δδ target) based on a requested steering angle and a current steering angle; controlling (s102) the electric power steering system (EPS) to temporarily provide a steering torque corresponding to a first target steering angle change larger than the determined target steering angle change (Δδ target), when the determined target steering angle change (Δδ target) is lower than a predetermined threshold value; determining (s103) a steering angle velocity and/or steering angle acceleration resulting from the provided steering torque; and determining (s104) whether a hydraulic failure has occurred based on the determined steering angle velocity and/or steering angle acceleration.