The Institut für Kraftfahrzeuge Aachen of RWTH Aachen University and the School of Transportation Design of Pforzheim University have presented a new research vehicle named SpeedE. Amongst other innovations, the vehicle is equipped with a new steering system with individually steered front wheels and high achievable steering angles controlled by active sidesticks and a vehicle dynamics controller embedded into a functional safety concept. This paper presents the development of the active sidestick components and the implementation of the forward and feedback control into the vehicle dynamics controller. The steering system of the research vehicle SpeedE is equipped with individual steered front wheels with high achievable steering angles. It is designed as a steer-by-wire system controlled by active sidesticks. The system additionally comprising a vehicle dynamics controller is embedded in an overall functional safety concept. At the same time the implementation of active sidesticks offers all advantages of steer-by-wire systems and opens new possibilities in the design of the cockpit including the dashboard and the human machine interface. The forward control is realized by detecting the driver's hand forces, which are then transformed into a steering angle based on a single track vehicle model. A modified Ackermann function then calculates the wheel steering angles depending on the driving situation, in order to achieve a tension free rolling at low speeds and a good longitudinal and lateral force exploitation at all speeds. The vehicle dynamic control functions finally adds correcting steering angles in order to keep the vehicle stable and agile. However, due to the single-steered wheels and the integration of a vehicle dynamics controller the sidestick feedback to the driver is challenging. The sidestick angle is calculated on the basis of the current curvature of the vehicle´s trajectory. The curvature is the most appropriate value for the description of the lateral behavior as it is velocity-independent and corresponds to the visual perception of the driver. The determination of the course curvature is done depending on the driving situation. The algorithms are based on the desired steering angle, the measured steering angle and the measured vehicle driving state, e.g. yaw and lateral acceleration reaction. A final application of the functionalities can only be done with real hardware and using several driver types.
Potentials and challenges for the application of active sidesticks - case study "SpeedE"
2012
12 Seiten, 8 Bilder, 8 Quellen
Aufsatz (Konferenz)
Englisch
Potentials and challenges for the application of active sidesticks - case study "SpeedE"
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