LONDON The Ford Motor Company in the U.K. has streamlined emissions diagnostics systems for European production cars using The MathWorks modeling and simulation software MATLAB and Simulink.
The tools and model-based design has enabled Ford engineers to reduce the need for access to prototype vehicles, shorten and combine analysis processes, and provide reusable models of engine control unit behaviour, cutting development time and cost.
All new vehicles sold in Europe are fitted with European onboard diagnostics (EOBD) devices, which monitor engine emissions and compare them with predefined fault thresholds. These devices report faults using dashboard indicators or diagnostic codes relayed to service technicians.
Developing the calibration for the diagnostics systems requires extensive access to prototype vehicles to measure their performance characteristics. Engineers analyse these characteristics and use the results to program the diagnostic system to recognise emissions errors while ignoring other unrelated fluctuations in engine performance.
The MathWorks tools enabled Ford engineers to streamline the process of EOBD calibration. Ford's previous calibration methods required precise measured data at all operating points to fill calibration maps. Using the Model-Based Calibration Toolbox and design of experiments (DOE) tools they developed test plans that take the most critical test points, reducing testing requirements. They then used the statistical modelling capabilities of the toolbox to create accurate and robust multidimensional models of the system throughout the operating range.
Engineers generated and optimised calibration maps and populated calibration tables. Rather than evaluate and refine the calibration with physical testing, Ford imported the calibration and test data into a Simulink model and then simulated the model using input signals acquired while collecting the original test data. Engineers can optimise and re-evaluate calibrations on the desktop, comparing results from different simulations to see the effect of calibration changes.
Ford is currently extending the use of MathWorks tools to other aspects of engine calibration, including exhaust and cooling systems. As a result of the EOBD project, Ford now has reusable models of engine control-unit behaviour, which can eliminate the need for new test data for some future developments.