A Multi-Layered and Modular Design Approach for Developing AMT Control System in Battery Electric Vehicles 2012-01-0963

The battery electric vehicle (BEV) equipped with automatic mechanical transmission (AMT) can realize gear-shifting automatically based on the optimal shift schedule and thereby gains higher economy and dynamics performances as well as easy drivability. As one of electronic control systems in BEV, the AMT control system takes charge of drivetrain control and plays an important role. However, nowadays the development of electronic control systems in automobile industry is facing a variety of challenges which mainly arise from complex functional requirements and market pressure, and it's the same to the development of AMT control system.

This paper presents a multi-layered and modular design approach for the development of AMT control system in a battery electric bus. The multi-layered design approach divides system into two high-level layers, each of which is then divided into a number of low-level layers. One high-level layer is the basic driver layer which is responsible for TCU (Transmission Control Unit) onboard devices driving and task scheduling; the other one is the advanced control layer which is responsible for advanced control strategy such as shift-decision making, shift timing control, fault handler and so on. The standardized application program interface (API) is applied to accomplish the interlayer interaction. Meanwhile, the modular design methodology is used in each layer to break down system function into modules, each of which accomplishes one sub-function and then is integrated to drive the complex function through sharing and combination and swapping. This modular design method allows system to be manageable for the purpose of implementation and maintenance. The modules in basic driver layer are developed in C language, while the modules in advanced control layer by MATLAB/Simulink/Stateflow tools. Finally, the experiment results are analyzed to show how the approach benefits the AMT control system development.