After defining the simulator requirements, VSI identified the major components of the truck and purchased off-the-shelf hardware to build the simulator. This enabled them to begin testing the Society of Automotive Engineers’ J1939 recommended heavy trucking networking practice for the Department of Transportation, Federal Motor Carrier Administration.
Using Simulink®, VSI developed and simulated plant models for all of the major heavy truck components, including the engine, transmission, vehicle, instrument panel, collision avoidance system with adaptive cruise control, and anti-lock braking system with traction control.
They then validated their models by comparing the performance with data obtained from an actual truck with a similar configuration as the simulator. Tuning the parameters within the Simulink models helped them obtain a high-fidelity representation of the physical plant of the truck.
VSI then automatically generated C code from their models using Simulink Coder™, and ran the code in real time on the simulator’s distributed PC processors using Simulink Real-Time™. The PCs use Athlon processors, I/O cards for each ECU, and a high-speed CAN network that enables parameters to be exchanged among the models in real time. This configuration lets VSI run simulations of the entire truck dynamics.
“The predefined libraries within Simulink Real-Time expedited the development process for us,” notes Long. “We just drag and drop new I/O blocks and get them running much more quickly than if we had to write I/O drivers at the code level in C.”
For their hardware, they used counter timer cards, buffered and nonbuffered digital I/O cards, and other I/O hardware from several vendors—all connected using the PCI bus. The separate ECU simulators were interconnected using the CAN networking support provided by Simulink Real-Time. This multiprocessor system was run at 1 KHz.
“Simulink Real-Time gave us the greatest range of target hardware and I/O interface cards on which we could run our models,” says Long. “We really liked the breadth of hardware support.”
VSI is currently testing the system using a driver’s station. The target PC connected to the driver’s station sends out timing signals and serves as the timing master for all of the other target PCs. They will deliver the results of the J1939 study to the DOT.