Abstract
This research project presents a system of fuzzy adaptation of the steering ratio. This study fits into the scheme of the current manufacturers which is to improve the comfort and the security of the passengers. The tendency is with the generalization of the electrification in automotive vehicles, and this with an aim of acting more quickly and of freeing themselves from the significant mechanical constraints hitherto. This study deals more particularly with variable steering ratio' (steering angle/wheels angle), and will try to answer the following questions :
- according to which information the steering ratio must be determined without disturbing the driver's behavior ?
- what must be the transition strategy from a value to another according to the driving situation?
The results reported in this paper are obtained on the basis of fuzzy mathematics through simulations and implementation on a vehicle control laws. At the moment the international legislation forces all the passengers cars to have a steering system mechanically related to the wheels. An adaptation of the steering ratio according to the speed of the vehicle as well as the steering angle would allow for example, to improve the driving comfort in particular in maneuvers such as 'reverse parking'. This new steering design can claim to bring the following gains:
an optimal adaptation of the steering wheels according to the driving situation and the environment of the vehicle
a feedback adapted to the driver and to the driving situation
a reduction of body damage caused by the intrusion of the steering column during a frontal shock
a compactness of the steering system
a compensation of anomaly intrinsic to the vehicle (steer pulling, etc.)
The main functions that this steering system must carry out remain unchanged, because whatever the innovation of the system is, this one must be able to answer the current criteria such as the steering precision, the progressiveness of angular dynamics, the steering stress, the steering recall, keying, the regularity of the answer, the steering reactions, etc.