Handwheel Force Feedback for Lanekeeping Assistance: Combined Dynamics and Stability

Lanekeeping assistance could save thousands of lives each year by maintaining lane position in the absence of driver steering commands. In order to work smoothly with the driver, handwheel force feedback must be an integral part of such a system. Here we combine force feedback with a lanekeeping controller based on lateral and heading error. In addition to force feedback replicating the feel in a conventional vehicle, the force can be based on the level of lanekeeping assistance being given. This coupling of the force feedback and assistance systems can destabilize the vehicle if not designed properly. Linear modeling verified by experiments shows the effect of varying the gains on both the force feedback and the lanekeeping assistance itself. In this analysis we show that within a range of values that feel reasonable to the driver, changes to the lanekeeping controller or force feedback can have marked effects on the response of the vehicle. It also shows that stability of the system can be ensured by injecting artificial damping or reproducing the on-center characteristics of a conventional vehicle. The analysis allows the force feedback designer to determine a range of stable force feedback gains, from which a set most acceptable to the driver can be chosen.