Regelkonzepte zur Fahrzeugführung unter Einbeziehung der Bedienelementeigenschaften

The conventional, mechanical Human-Machine-Interface (HMI) for vehicle guidance (e.g. steering) usually has a fixed gear ratio, and transmits non-adjustable driver command. In this configuration, compromises must be reached between different desired objectives. In the case of automobile steering, agility, stability, comfort at all vehicle velocities and various driving tasks are some objectives that must be considered. This need for compromise may be resolved with the so-called “By-Wire” technology (e.g. Drive-by-Wire, Fly-by-Wire, etc) where electronics replaces mechanical components for command transmission. The feedforward and feedback between driver and vehicle can be influenced by software with new control systems with By-Wire technology. Therefore, the subjective driving impression of the complete driver-vehicle-system can be adjusted according to designers’ wishes. This thesis investigated the suitability of feedforward and feedback vehicle guidance control for the complete driver-vehicle-system. First, the correlation between subjective evaluations and objective measurements was examined. The relevant driving variables of state were used to derive the suitable guidance concepts. Through the operator’s tactile sensing, the feedforward and feedback control occur seamlessly, therefore they should be examined collectively. The connection between feedforward and feedback can be established through the two-port model of network theory [Hannaford, 1989]. The driving concepts for the vehicle guidance could then be clearly analyzed in a systematic fashion. Different concepts were present and compared. The omnipresent real-world issues of delay-time (e.g. signal delay, mechanical transmission delay), as well as the lateral nonlinear situation were also considered. For the vehicle’s longitudinal guidance, the driving concept of “feedforward-force proportional to vehicle velocity” may be applied for a passive or active HMI, with spring-damperlike properties with changes of position. In case by a position-free (isometric) HMI, the driving concept of “feedforward-force proportional to vehicle acceleration” should instead be implemented. For the lateral guidance at low vehicle velocities, the driving concept “feedforward-force proportional to yaw-rate and feedback-position from curvature-radius” should be suitable. At middle and high vehicle velocities, the feedforward-force will be proportional to the lateral acceleration and the feedback-position should be calculated from the yaw-rate. New driving concepts may be developed for evaluation and deployment using the HMI control methods presented in this thesis. With these lateral and longitudinal control methods, many of the compromises present in traditional mechanical steering can be eliminated or alleviated, thus providing improved HMI properties and the driving experience.