Abstract
The amount of electric and hybrid electric vehicles in development or offered on the market is strictly increasing. To make such vehicles more efficient a common method is energy recuperation during braking. So the generator and hydraulic friction brake have to interact, called brake blending. A main focus of the development of braking systems with the ability for recuperation is the quality of the Human-Machine-Interface (HMI). The aim of the HMI is to give a feeling of authenticity and safety; it also should enable an intuitive brake actuation, so that brake situations and actuations have to be reproducible. This Paper shows in a first step the benchmark of vehicles with regenerative braking systems in combination with decoupled brake-by-wire and conventional coupled braking systems. Typical characteristics are analyzed. In a further step the results of the benchmark are validated with test drives in a special built up research vehicle with programmable pedal and brake characteristic with a wide spectrum of parameters. So the aim of the paper is to infer from objective characteristics to subjective feelings, especially with the focus on disturbances in deceleration caused by the interaction of components of the regenerative braking system.
KEYWORDS – Human-Machine-Interface, Brake pedal feeling, Brake-by-wire, recuperation, Electric vehicle