RDE Plus – The Development of a Road, Rig and Engine-in-the-Loop Test Methodology for Real Driving Emissions Compliance 2019-01-0756
The introduction of the Worldwide Harmonised Light Vehicles Test Procedure (WLTP) and Real Driving Emissions (RDE) test drive cycles have put increased strain on vehicle and engine performance as well as the requirement for the development of advanced engine technologies and emissions mitigation strategies. This requirement for increased development is ultimately a direct result of the need for new vehicles to comply with present and emerging emissions standards across an extended range of boundary conditions that include altitude, ambient temperature and driving style.
To reduce the significant number of test permutations of altitude, ambient temperature and driving style that would ordinarily be required to homologate a given vehicle across the RDE defined boundary conditions, a “Road to Rig” development approach known as RDE Plus (RDE+) is being evolved at HORIBA MIRA. This will enable real world driving scenarios to be developed and deployed much further upstream during the development lifecycle of the vehicle and engine using aspects of virtual calibration, with the aim of significantly reducing vehicle and engine development costs and associated timescales.
Road RDE data is presented in the current report from vehicles of different powertrain technologies gathered from several European test locations under conditions representing the ambient temperature, altitude and driving style boundaries defined by the RDE protocol. Upon gathering a combination of vehicle CANBus, custom instrumentation and emissions (Portable Emissions Measurement System (PEMS)) data, a number of the recorded RDE routes were replicated using the same vehicles on a chassis dynamometer with a view of developing a standardised practical approach to replicate RDE tests in the laboratory environment.
These tests were performed at HORIBA MIRA in the Advanced Emissions Test Centre (AETC) (with the data being presented in the current report) with the aim of defining a chassis dynamometer test methodology suitable for different powertrain technologies that results in an accurate representation of on-road conditions with respect to vehicle load, ambient temperature and altitude conditioning and emissions.
Following the road and chassis dynamometer correlation, the vehicle engines will be installed on an engine dynamometer with the objective of developing a suite of “golden” RDE cycles using an Engine-in-the-Loop (EiL) type approach. By frontloading RDE development using an engine test bench and virtual environment it is possible to rapidly screen hardware and develop engine and vehicle calibrations using a Design of Experiments (DoE) type mapping approach with a view to creating several “worst case” RDE cycles (within the RDE boundary conditions) that are specific to a given engine and vehicle technology and configuration. These “golden” RDE cycles can then be adopted for complete vehicle and engine homologation irrespective of ambient temperature, altitude and driving style. The methodology to develop these “golden” RDE cycles in combination with an overview of RDE+ is discussed in the current report.
Philip John Roberts, Richard Mumby, Alex Mason, Lewis Redford-Knight, Prabhjot Kaur