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The ever-growing number of interacting electronic vehicle control systems requires new control algorithms to manage the increasing system complexity. The paper describes a torque-based engine control architecture which uses a central torque demand variable to control the regulating qualities. This torque demand variable is the result of the coordination of all torque requests throughout the vehicle. Therefore, the system manages the whole process of prioritizing the torque demands of the different subsystems such as electronic stability or transmission control. If further vehicle subsystems have to be integrated, the structure can be easily extended as the torque demand variable is the only interface between the engine control algorithms and other vehicle control systems.

A project has been carried out to develop a practical G-DI vehicle with very low emissions; primarily assessed over the European EUDC cycle, but with emissions consistent with ULEV, Euro Stage IV and Japan 2000 legislation whilst maintaining acceptable driveability. A combined test bed and vehicle programme was conducted. Vehicle benchmarking established target emissions reduction areas and testbed work characterised the combustion system. The programme was based on a Mitsubishi Carisma GDI™ vehicle. The vehicle used a prototype Lean NOx Trap (LNT) based aftertreatment system. The Ricardo Vehicle Engine Management Prototyping System (VEMPS) Control System replaced the OEM ECU giving control of drive components and strategies to regenerate LNT of stored NOx were developed. Constant torque during regeneration spikes was achieved. The fuel economy penalty of different regeneration strategies was investigated.

Conventional exhaust gas analyzers are of limited use in transient engine testing as the dynamics of the analyzers cause distortion of the emissions measurement during transients. An advanced technique is presented which uses signal reconstruction to determine the actual emissions during engine transients from the distorted output of a conventional exhaust gas analyzer. The reconstruction technique is based on the design of a finite horizon filter which is a dual of generalized predictive control theory. Results are presented which demonstrate the use of this technique for reconstruction of instantaneous emissions from a diesel engine over a part of the US heavy duty test cycle. The results show that the reconstructed emissions recover significant information which is otherwise obscured by the distortion introduced by the analyzer dynamics.

Ricardo have developed a systematic approach for the design of transient engine control strategies using advanced control techniques. The methodology was initially applied to the design of a testbed speed and torque controller. This enabled complex transient tests to be carried out with equipment normally used for steady-state testing. The same techniques were applied to the design of a controller for a variable geometry turbocharger aimed at vehicle applications. The influence of different control strategies on emissions and fuel economy was evaluated on a heavy-duty diesel engine over a section of the US FTP cycle. Particulate reductions of up to 34% were achieved without increasing NOx.