The control system has been designed and developed focusing on its simplicity. Regarding the mechanical part, a step-by-step electric engine allows to move the steering wheel with a high resolution and with a reduced power consumption.
On the contrary, the simplicity of the logical part of the control system has the main advantage of keeping the entire system robust: the position that the vehicle will assume in 1.5 seconds is computed (this requires the knowledge on the vehicle speed and angle) and in case it is not central with respect to the lane, a rotation -proportional to the error- is imposed to the steering wheel.
With this kind of control, for speeds up to about 90-95 km/h there is no difference with a human driver, while for higher speeds (during the test a peak of 123 km/h has been reached) the vehicle tends to get a slightly instable behavior, waving inside the lane.
It is currently under study a more sophisticated control system including also a strong model of the road; this will allow to reach higher speeds with a smoother behavior. This new control mechanism is under test on a system simulator that allows to emulate the behavior of the vehicle on a curved road with more than one lane. It has been used also to test the lane change maneuver.