A lot is going on in commercial applications: New powertrains, higher efficiency auxiliaries or digitization are opening up new ways for developers to optimize products. Exploiting this potential to the full involves detailed simulation of entire systems, such as commercial vehicles or mobile machines. To this end, IAV uses its proprietary Velodyn for ComApps tool throughout the development process.
What does the optimum powertrain layout look like? Does a 48-volt electric system make sense? What’s the situation with the interaction between hybridization and waste heat recovery? These and many other questions of this type are currently a particular concern to the developers of commercial vehicles, like trucks or mobile machines – because in view of forthcoming CO2 limits and the demand for the lowest possible running costs, commercial-vehicle manufacturers are opting for products that make optimum use of precious energy. But the best results can only be achieved by being able to simulate the full range of all relevant factors as accurately as possible and under realistic conditions. The sum of optimized components yet doesn't produce any optimum overall system.
Comprehensive library of components and test cycles
IAV follows this all-encompassing approach in its development projects, and it does so using the Velodyn for ComApps tool developed in-house. It provides many virtual vehicle components as well as numerous test cycles in a comprehensive library, is suitable for on-highway and off-highway applications and covers all of the vehicle’s relevant subsystems. Simulink is being used to simulate the overall system, energy management and control algorithms. Simulink also permits the integration of further simulation tools, such as GT-Cool and Dymola (cooling), GT-Power and Amesim (engine), axisuite (exhaust gas aftertreatment) and Amesim (hydraulics). Simscape is also used in Velodyn for ComApps to simulate the commercial vehicle’s mechanical components and the simple hydraulic systems.
“The solution we have developed lets us simulate commercial vehicles in a comprehensive and highly targeted manner. This is particularly important because in this domain the manufacturers are facing many changes, such as downspeeding of combustion engines or new electric systems operating on 48 volts”, says Tobias Töpfer, manager of the Overall Systems, Alternative Drives and Hybrid team at IAV. “On-demand control of auxiliaries as well as systems for using energy from exhaust gas heat can reduce fuel consumption on a noticeable scale – but at the same time, we must always look at system interaction and not only focus on the various constituent parts.” Because this is the only way of getting the full picture of which operating strategy and which type of energy management deliver the best results under realistic operating conditions.
Variant management with just a few prototypes
A typical scenario for using VeLoDyn for ComApps is variant management. As the number of prototypes actually in existence is limited for cost reasons, the developers cannot measure every variant on the road or test bench. In this case, the data measured for a prototype can be used to generate and simulate virtual variants of the vehicle – e.g. equipped with a different engine or a new type of transmission. The comprehensive library of vehicle components quickly makes it possible to generate such variants and simulate them in detail under various boundary conditions (including topography, climatic conditions and degree of capacity utilization). For this purpose, Velodyn for ComApps provides a library of common test cycles, including cycles familiar to the industry, such as those shown in lastauto omnibus magazine.
But the solution can also be of help if a realworld prototype unexpectedly encounters problems during a test drive or if phenomena occur that cannot be reproduced in specific driving situations. In the back office, Velodyn for ComApps can then be used to search for the cause. The results from PEMS (Portable Emissions Measurement System) measurements can also be predicted throughout the end-to-end system simulation – making it possible to reduce test drives and also providing the capability of analyzing an engine by “engine in the loop” on the test bench and under simulated boundary conditions. Algorithm developers use the tool, for example, to program new controllers for control units. And the increasing digitization of commercial vehicles can also be simulated – e.g. for predictive thermal management which, when it comes to fan operation, not only takes account of the route but also the current traffic situation.
Indispensable tool in many projects
Velodyn for ComApps has been in successful use at IAV for many years and has proven its worth in many customer projects. “Without a tool of this type, it is no longer possible to understand or calibrate modern commercial vehicles”, Töpfer says. “We use it throughout the entire development process – from the initial concept phase to calibration and field tests.” In 2015, for example, it was used for various inhouse projects at IAV where the focus was on the synergies between a 48-volt vehicle electric system and use of waste heat, predictive thermal management and the potential from aerodynamic measures on the commercial vehicle.