Digital Route Planning for RDE Measurement Drives

It is a legal requirement in the European Union for motor vehicle emissions to be measured not just on the roller dynamometer but also in real road traffic. However, a test route has to fulfill many criteria in order to comply with the statutory RDE requirements. When it comes to RDE route planning, IAV uses a specially developed tool for defining a route at the desk and simulating the course of the run. This gives a high degree of certainty already before the real measurement drive as to whether the results will be valid or not.

An RDE measurement drive takes up to two hours, with detailed stipulations to be met in terms of ambient temperature and differences in altitude. The route has to be made up of one third urban roads, one third non-urban roads and one-third highways. In most cases, route planning takes more than a quick look at the map. In unknown regions purely manual planning is difficult anyway, but even in familiar settings it takes a lot of time and test drives to create an RDE-compliant route.

IAV experts have therefore developed an innovative tool: simulation software that generates map-based RDE routes. The software is programmed in Matlab and uses freely available or commercial map material. The starting point and destination can be defined at the desk together with any number of interim stops. The shortest connection is then calculated automatically. The user sees the route’s speed and altitude straightaway as well as the shares of urban roads, non-urban roads and highways.

The tool even simulates the measurement drive itself for an even better assessment of the planned route. “A virtual vehicle moves through the traffic. The vehicle’s speed or the time it spends waiting at traffic lights can be adjusted according to realistic traffic volumes. The simulation tool also takes account of the driver’s style”, explains IAV’s Technical Consultant for Diesel Exhaust Gas Aftertreatment, Johannes Scholz. “In the end, the software shows whether the simulated run really did conform with the RDE requirements.” If this is the case, there are many reasons to believe that the real route will then also be suitable for a measurement drive, thanks to the excellent coincidence revealed by a comparison between simulations and real runs. If the route is not yet suitable for an emission test, the user can make changes without any problems and proceed with another simulation.

The simulation software is suitable not just for preparing real measurement drives with PEMS equipment. “We can also generate the driving track for simulation environments, including our modular models for engine, exhaust gas aftertreatment or the whole vehicle”, says Dr. Michael Monteforte, IAV development engineer for exhaust gas aftertreatment.” The computed routes can also be used on our climate roller dynamometer for altitude testing in Berlin.”

The simulation has already proved its worth in several customer projects, clearly reducing the time taken to create the route, particularly for measurement drives in unknown regions. In future, the software will also automatically create routes from a defined starting point and optimize them autonomously in terms of critical boundary conditions.