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For each operating condition, numerous measurement variables are needed to be performed and averaged to show the desirable robustness. A tremendous number of cycles need to be run in the engine test-bed to acquire sufficient data to fill in the lookup table, which takes a significant amount of time for calibration. The most popular control method of automotive engineering is the model-free methodology to design engine control units (ECU). Therefore, AFR regulation has been a popular topic in areas over automotive industry and theoretical research. In addition, the dynamics of the air manifold and fuel injection of internal combustion engines are very fast, severely nonlinear, and constraints are imposed on the states and inputs. If AFR is 1% higher than 14.7, up to 50% more NO x will be produced. If AFR is 1% lower than 14.7, the emissions level of carbon monoxide (CO) and hydrocarbons (HC) can increase significantly. It has been reported that only the stoichiometric value provides its optimal operating condition. The efficiency of three-way catalysts (TWC) is significantly influenced by the air fuel ratio. For example, in order to obtain the desired balance between power output and fuel consumption in spark-ignition (SI) engines, the air/fuel ratio (AFR) must be maintained at the stoichiometric value (14.7) for both steady state and transient operation. However, the high-performance control of the dynamics of internal combustion engines is difficult to achieve due to unpredictable changes of load. It needs not only design efforts on engine operating conditions, but also the reliable methods to measure system states, which is needed for the implementation of control strategies. The primary objective of modern engine control systems is to maintain the combustion process at the low-emission condition while satisfying the requirements on higher efficiency, performance, and reliability.