METHOD AND SYSTEM FOR SAFE LIMITING OF TORQUE OVERLAY INTERVENTION IN A POWER ASSISTED STEERING SYSTEM OF A ROAD VEHICLE

摘要

Disclosed herein is a method and arrangement for safe limiting of torque overlay intervention in a power assisted steering system of a road vehicle having an autonomous steering function arranged to selectively apply a steering wheel overlay torque to a normal steering assistance torque. A wheel self-aligning torque (ƒ_R) of the road vehicle is modelled for a current vehicle velocity (ν) and pinion angle (δ_w). A steering wheel overlay torque request (τ_R) is received. Based on the received steering wheel overlay torque request (τ_R) is provided a steering wheel overlay torque (τ_A) in hands-off applications limited to a safe set interval that is symmetrical around the modeled wheel self-aligning torque (ƒ_R).