Annual Reviews in Control 41 (2016) 94–118 Contents lists available at ScienceDirect Annual Reviews in Control journal homepage: www.elsevier.com/locate/arcontrol Review A review on control system architecture of a SI engine management system B. Ashok * , S. Denis Ashok, C. Ramesh Kumar School of Mechanical Engineering (SMEC), VIT University, Vellore 632014, India a r t i c l e i n f o Article history: Received 28 May 2015 Revised 28 January 2016 Accepted 15 February 2016 Available online 5 May 2016 Keywords: Engine management system (EMS) SI engine control algorithm Sub-control module Control system architecture Torque a b s t r a c t Engine management systems (EMS) has become an essential component of a spark ignition (SI) engine in order to achieve high performance; low fuel consumption and low exhaust emissions. An engine manage- ment system (EMS) is a mixed-signal embedded system interacting with the engine through number of sensors and actuators. In addition, it includes an engine control algorithm in the control unit. The control strategies in EMS are intended for air-to-fuel ratio control, ignition control, electronic throttle control, idle speed control, etc. Hence, the control system architecture of an EMS consists of many sub-control modules in its structural design to provide an effective output from the engine. Superior output from the engine is attained by the effective design and implementation of the control system in EMS. The de- sign of an engine control system is a very challenging task because of the complexity of the functions involved. This paper consolidates an overview of the vital developments within the SI engine control sys- tem strategies and reviews about some of the basic control modules in the engine management system. © 2016 International Federation of Automatic Control. Published by Elsevier Ltd. All rights reserved. 1. Introduction Enhancements in fuel economy and emission reductions are two active areas of engine research. Advanced engine control tech- niques are engaged because of the strict emission regulations and demand for higher fuel economy. It is of great importance to de- sign the power train components in order to improve the fuel ef- ficiency and reduce emissions while fulfilling drivability and ride comfort issues. Control has always been a part of engine design and it is one of the most complex problems in the application (Stobart, Challen, & Bowyer, 2001). Automobile engines effectively encompass the spirit of mechatronic systems with their abundant application of electronics, sensors, actuators and microprocessor based control systems to provide improved performance, fuel econ- omy and emission levels. The classical approach of engine-control tasks is accomplished by means of a mechanical approach, but now it is being replaced by electronic control systems. In such systems, engine performance such as power, torque, fuel-consumption and emission level, is significantly affected by the control strategies followed in the engine management system (EMS) (Lee, Park, & Sunwoo, 2004). The modern spark ignition engines are generally equipped with an EMS whose task is to provide the desired output from the engine and it plays an important role in the driver’s con- * Corresponding author. Tel.: +91 9865467729. E-mail address: ashok.b@vit.ac.in, ashokmts@gmail.com (B. Ashok). trol of the vehicle. It controls the operations such as ignition, air- to-fuel ratio, idle speed and complex variable valve timing, etc., in order to reduce the emissions and improve the average fuel econ- omy (George & Michael, 2014). Compared with ordinary embedded systems, it requires more stringent demands on reliability, resource sharing and cost efficiency (Guojun, Wenqing, & Youtong, 2010). Engine management system (EMS) usually consists of various sensors to monitor the real-time operating conditions of the en- gine and actuators to control injector, spark plug, throttle, etc. The control signal sent to different actuators is accomplished by means of the EMS control system, which is comprised of a large number of control modules (control loops) in its architecture. The schematic representation of the control system architecture of SI engine is shown in Fig. 1. Some of the basic modules within the EMS which are coordinated with the torque control module are, 1) air–fuel ratio (AFR) control; 2) electronic throttle control (ETC); 3) idle speed control; 4) ignition timing control; 5) knock con- trol; 6) diagnostics control, etc. Besides these modules, cam shaft control, turbocharger, EGR, after treatment controls, etc. are also a part of the control modules in an actual production vehicle EMS (Andreas & Torsten, 2001; Guenther & Gerhardt, 2000; Guzzella & Onder, 2010; Hammel, Jessen, Andreas, & Harald, 2003; Hillion et al., 2008; Hong et al., 2013; Isermann, 2014; Jurgen, Honninger, & Bischof, 1998; Le Solliec, Berr, Colin, Corde, & Chamaillard, 2007; Le Solliec et al., 2007; Ribbens, 1998). All these modules are run in parallel to the torque control structure in order to produce the de- sired engine output as demanded by the driver. Other modules are http://dx.doi.org/10.1016/j.arcontrol.2016.04.005 1367-5788/© 2016 International Federation of Automatic Control. Published by Elsevier Ltd. All rights reserved.