Automated Test of CVT Control Software, Using FMI and Modelica Models

Hunan Jianglu & Rongda Vehicle Transmission Ltd., Co. has recently completed the development of a Continuously Variable Transmission (CVT). The transmission and the control software must be fitted to various vehicle platforms and must suit various driving conditions and driver requests. Because of the complexity of the system and due to the large number of driving conditions, systematic tests and validation methods are required. These methods should guarantee correctness and quality of the software and system behavior. For the test of the control software, Jianglu Rongda used an innovative test method based on automatic test scenario generation, Software in the Loop (SiL) simulation, and finally Hardware in the Loop (HiL) tests. The CVT control software is executed with a vehicle simulation model developed with SimulationX/Modelica, which is used both for the SiL and the HiL tests. The model accurately represents the CVT transmission including mechanical and hydraulic systems based on mechanical and physical parameters. In this paper, we describe the corresponding test process and tool chain along with the model validation. We also discuss the advantages and costs of this approach.