Anti-lock braking systems for the full electric vehicles are characterized by the control structure of higher complexity due to the combined use of actuators with different performance and capabilities. In the discussed research the vehicle prototype is represented by a full electric sport utility vehicle equipped with four individual on-board motors. The study includes problems of (i) integration of the electric and electro-hydraulic brake systems on the vehicle prototype and (ii) development of advanced wheel slip control strategy aimed on the reduction of the stopping distance, enhancement of the driving comfort during the braking, ensuring safe operation and maximal energy recuperation.
The proposed brake system integration is done to realize the combined use of electric and hydraulic brake actuators during the emergency braking situation. In particular, it is aimed at the achievement of the maximal energy recuperation and reduction of the friction brakes use. The proposed wheel slip control approach is based on the PI-controller with the gain scheduling according to the vehicle velocity.
The achieved results showed the reduction of the stopping distance not only on the stage of hardware-in-the-loop system testing, but confirmed enhanced vehicle safety on the vehicle demonstrator. The road tests were performed at the Lommel Proving Ground on the surface with low friction conditions. Besides the developed approach, several ABS configurations were tested on the vehicle. In particular, all results were compared with the serial vehicle of the same type with internal combustion engine, conventional hydraulic brake system and rulebased ABS. Final benchmarking shows significant reduction of the stopping distance and improvements in driving comfort during the emergency braking in the case of developed continuous ABS algorithm.
The proposed brake system architecture shows possible benefits and enhancements, which can be realized by the full electric vehicles with individual wheel torque distribution. Developed ABS control functions showed considerable reduction in the stopping distance and improvement in the driving comfort. The proposed brake system architecture and ABS functions in particular have a huge potential in further use on full electric vehicles.
Dzmitry Savitski, Valentin Ivanov, Klaus Augsburg - Ilmenau University of Technology - Robert Wragge-Morley - University of Bristol Thomas Pütz - TRW Automotive Paul Barber - Jaguar Land Rover