Modeling of an Electro-Mechanic Brake-by-Wire System for the Robomobil

Kurzfassung

The Robomobil (ROMO), a new research project of the German Aerospace Center (DLR), deals with the development of an electric driven vehicle using a brake-by-wire system. To describe, and in a further step to optimize the system characteristics of ROMO, a Modelica library was developed by DLR. At the current status, the part of the library describing the brake-by-wire system, is a rough approach. Therefore, in this thesis a new, more realistic sublibrary of the brake-by-wire system is developed. Dymola is used as the main software tool implementing the analytical models, using MATLAB for data processing and interpretation as well as ANSYS for FEM based parameter studies from CAD data. For the parameterization, manufacturer specifications of ROMO’s brake are used. The missing parameters are computed analytically. To derive the brake-by-wire model, its components - hydraulic, electrical and mechanical - are modeled individually, based on physical considerations. The focus of the modeling is on hydraulic and mechanical elements. Modeled hydraulic characteristics are the hydraulic capacity and the flow resistance of several brake-pipe elements. The mechanical part consists of models describing the spindle drive and the brake caliper. In order to proof the quality of the models the thesis also focuses on model validation. Finally, a controller is added to the brake-by-wire system. The purpose of the controller is to control the actual brake pressure in the brake system.