2018 Award Winners
Award-winning project: Real-time control of passenger car powertrain test benches for realistic vehicle testing
Project partners: Daimler AG, Stuttgart | Steinbeis Transfer Center Traffic Engineering. Simulation. Software, Niederstotzingen
The requirements placed on vehicle powertrains are diverse and meeting them in terms of driving performance, emissions, service life and fuel consumption demands a great deal of effort. To enable efficient development within a short timeframe, computer and test bench simulations, as well as road tests, are carried out. During road tests, real-world route data is recorded, which serves as the basis for the simulations. It is a highly challenging task from a control engineering perspective to replicate driving cycles measured in real-world conditions on a powertrain test bench, as the components of the powertrain exhibit significant dead times and non-linearities. The previous method, in which the test bench was controlled using measured data, required a great deal of effort in parameterisation and often led to stresses in the test bench structure, resulting in unrealistic results.
To resolve this problem, Daimler AG, Stuttgart – representing Powertrain Development and the Powertrain Test Facility – approached the Steinbeis Transfer Centre (STZ) for Transport Technology, Simulation and Software in Niederstotzingen to develop a test bench control system for powertrains. Up to that point, Daimler AG had already been successfully using the ‘winEVA’ simulation software, developed by the STZ, to generate load profiles.
A combination of control and regulation was chosen as the final solution to the problem. To this end, the test bench control system carries out a real-time simulation of the powertrain using ‘winEVA’ under test bench conditions and transmits the control variables – accelerator pedal position and wheel speeds – to the test bench. The test bench’s responses are compared with those of the simulation model, and any deviations between the test bench behaviour and the simulation model are used to adjust the simulation model.
This fundamental approach has been continuously refined and further developed over the years, enabling the control of conventional, hybridised and highly dynamic, all-electric powertrains, as well as all-wheel-drive systems with complex all-wheel-drive strategies.
The project partners have been awarded the Steinbeis Foundation’s Transfer Prize – the Löhn Prize – in recognition of the innovative, forward-looking concept behind this project and the ongoing, mutually reinforcing development partnership.