RT-LAB makes model-based calibration of ECUs a reality

Current developments in engine and transmission technologies are being shaped by stringent emissions standards, and the customer’s demand for improved fuel economy and vehicle comfort. This has led to the constantly increasing complexity of vehicle control systems.

Optimal consumption, emission, and comfort can be best achieved when the entire drive train – including the engine, clutch, transmission, and vehicle dynamics – are calibrated together with engine control systems.

The IAV GmbH Berlin in cooperation with the Department of Electronic Measurement and Diagnostic Technology at the Technische Universität Berlin (Berlin Technical University) carries out project and research work focused on testing the entire drive train on a highly dynamic engine test-bench. The test-bench consists of equipment for controlling the combustion engine, a dynamic electric dynamometer, and measuring devices for exhaust-gas emissions and fuel consumption. An RT-LAB™ hardware in-the-loop (HIL) simulator from Opal-RT Technologies simulates the transmission and the rest of the vehicle.

The test-bench consists of equipment for controlling the combustion engine, a dynamic electric dynamometer, and measuring devices for exhaust-gas emissions and fuel consumption. An RT-LAB™ hardware in-the-loop (HIL) simulator from Opal-RT Technologies simulates the transmission and the rest of the vehicle.

RT-LAB is a PC-based, real-time simulator that provides engineers with a scalable, high-performance environment for hard-real-time simulations. RT-LAB hardware and software works with MATLAB/Simulink® or MATRIXx/SystemBuild™ modeling software. The RT-LAB simulator used for the test bench for this project is a single host, single target system that can be used in numerous real-time simulation/control applications typically found in industrial as well as educational projects.

"After examining hardware-based options from other vendors, we selected RT-LAB because of its use of low-cost PC hardware and scalability," said Dietmar Winkler, a researcher with the Department of Electronic Measurement and Diagnostic Technology, Technische Universität Berlin. "RT-LAB also provided us with the networking support we needed without forcing us to pay for support we didn't need."

The combustion engine was directly coupled with the dynamometer, which was controlled by a power converter. A control system was responsible for the management of all aspects of the test-bench. Signals were exchanged between the control system and the drive, as well as between the control system and the engine via physical input/output cards. All communication and data acquisition within the simulation took place in real-time.

Diagram of the test bench system
(Click to enlarge)

The HIL simulator and the control system communicated via a high-speed Gigabit Ethernet connection using the UDP/IP protocol. This communication link is managed by RT-LAB. RT-LAB also supports shared memory communication within a multi-processor or multi-core system.

"RT-LAB's support for UDP communications made a great difference in the success of this project," said Winkler. "And with Opal-RT's help, we were able to tailor RT-LAB to meet our needs while remaining within budget."

The real-time models of the drive train were developed on a standard PC workstation with VeLoDyn, a simulation tool developed by the IAV GmbH. VeLoDyn consist of vehicle and drive train models based on the MATLAB/Simulink environment.

Using RT-LAB, the VeLoDyn models were prepared for real-time simulation. Upon completion, the C-code of the models were compiled and executed. With RT-LAB, it was possible to monitor the simulation process via the network and even transfer new set points dynamically.

Included with RT-LAB is an application programmer interface (API) that allows most RT-LAB functions to be controlled with scripting tools such as LabVIEW, Python, or Visual Basic. Real-time data can also be displayed either directly in a Simulink-Scope or in LabVIEW.

A major advantage of RT-LAB connecting via a network was the possibility of remote control and remote access. As a result of using RT-LAB, development of the test-bench was completed in 6 months, with commercial use beginning in May 2005.

The IAV GmbH Berlin and the Department of Electronic Measurement and Diagnostic Technology at Technische Universität Berlin continue to conduct research using the test-bench, with a particular focus on hybrid-electric powertrain development using RT-LAB from Opal-RT and Dymola (Dynamic Modeling Laboratory) from Dynasim AB. Winkler expects the results of this current research to be published in October 2006, at EVS 22 in Tokyo, Japan.

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