In Cylinder Trapped Mass Estimation In Diesel Engines Using Cylinder Pressure Measurements Bilal Youssef, Fabrice Guillemin, Guenael Le Solliec, and Gilles Corde IFP Energies nouvelles - France (Bilal.Youssef, Fabrice.Guillemin,Guenael.Lesolliec,Gilles.Corde)@ifpen.fr Abstract— Advanced control systems and diagnosis algo- rithms for modern automotive engines need further feedback information of different events inside the cylinders. In this work, we propose a new method for in cylinder trapped mass estimation (TME), using instantaneous cylinder pressure measurements as input. The method is based on a graphical signatures generation tool, recently proposed for diagnosis and parametric estimation of nonlinear systems. A two dimensional graphical signature is generated from measured cylinder pres- sure. It is shown that generated signature is correlated with the value of trapped mass and thus enables us to design an TM estimator. Experimental Data obtained on a four cylinder diesel engine test bench has been used for off line static validation. The proposed method has been successfully implemented and tested on line using LTC Diesel vehicle. Keywords: Trapped mass estimation, Cylinder pressure, Internal combustion engine, Graphical signature. I. INTRODUCTION Future legislations require a significant improvement of automotive engine performance in terms of fuel consumption and pollutants emission. In particular, Diesel engine emission regulations are becoming increasingly stringent. To deal with these issues, advanced control systems and diagnosis algorithms need a good feedback information of different events inside the engine (combustion, injections, trapped mass,...). The supervision of these events and the estimation of their parameters allow a significant improvement of engine performance in term of fuel consumption and pollutants emission. With the availability of cylinder pressure sensors for modern engines, methods based on them can be used for a wide variety of applications like torque estimation [1], exhaust gas recirculation control and estimation ([2], [3]) and emission estimation [4]. This work is part of Cobcyl 1 project funded by the French ANR 2 in the framework of the VTT 3 program. The goal of this project is the development of real time strategies for the analysis and control of the engine combustion, based on low cost techniques oriented to industrial applications. In particular, the trapped mass estimation from in cylin- der pressure measurements given by Continental industrial sensor is considered here. Trapped mass determination is crucial for the control and diagnosis of modern automotive IC engines. To deal with this issue, many researches have 1 Cobcyl: Closed-Loop Control Based On Cylinder Pressure 2 ANR: Agence National de la Recherche 3 VTT: Programme V´ ehicules pour les Transports Terrestres been investigated recently ([5], [6], [7]). In this work, a graphical method [8] is used in order to design a trapped mass estimation scheme using cylinder pressure measure- ments. This method is based on a two dimensional graphical signature generated from engine measurements given by dedicated sensors. Signature is obtained using a projection from a high dimensional space containing past measurements in a moving window into a different space. This projec- tion highlights what happens inside the engine and enables to describe useful information about internal phenomena. Useful characters related to this phenomena can then be extracted by signature analysis. The extracted characters are then used to detect internal phenomena as well as to estimate phenomena’s parameters. In [9], the graphical tool has been proposed in order to extract useful information related to internal processes occurring in automotive engines using high frequency signals like crankshaft angular velocity and cylin- der pressure. The graphical signature generation method can be easily implemented in a generic engine control structure and used for real time applications. In [10] the signature based method has been applied to estimate the indicated mean effective pressure using the crankshaft angular velocity measurements. In the present paper, the signature based method is used in order to provide a trapped mass estimator for diesel engine. A two dimensional graphical signature is generated from the cylinder pressure measurements during the compression stroke. This signature is sensitive to trapped mass variation. A useful character which is correlated to the trapped mass value can be easily extracted from generated signature. Therefore, a trapped mass estimator can be de- signed based on an experimentally identified function that relies the trapped mass to character’s value. The estimation method is validated off line using real data obtained on diesel engine test bench and on line using LTC vehicle demonstrator provided by IFPEN. The obtained results clearly show the performance of the graphical tool for trapped mass estimation in static and dynamic operating conditions. The paper is organized as follows. Section II gives a brief description of existing methods dealing with the trapped mass estimation problem. An overview of the method used here is also given. The graphical signature tool is presented in section III and the mathematical definitions used for signature generation are briefly recalled. Section IV gives some experimental results in static and transient operating conditions. 2011 IEEE International Conference on Control Applications (CCA) Part of 2011 IEEE Multi-Conference on Systems and Control Denver, CO, USA. September 28-30, 2011 978-1-4577-1063-6/11/$26.00 ©2011 IEEE 561