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Christopher H. Onder - One of the best experts on this subject based on the ideXlab platform.
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Engine Knock detection: an eigenpressure approach
IFAC-PapersOnLine, 2019Co-Authors: Giulio Panzani, Sergio M. Savaresi, Jonatan Rosgren, Gabriele Pozzato, Christopher H. OnderAbstract:Abstract In this work, a Knock detection approach based on in-cylinder pressure principal component analysis is proposed. The introduction of a set of basis functions called eigenpressures used to describe the principal components of the pressure traces allows for an easy and effective separation between the typical “bell shape” component of pressure profiles and the Knock-induced pressure oscillations, making possible the classification of Knocking and not Knocking cycles. The proposed approach is compared to a standard Knock detection method based on the in-cylinder pressure trace band-pass filtering and to a pure data-driven algorithm. The method shows the best Knock classification performances and proves to be advantageous thanks to the low number of easily tunable parameters and their ease of calibration/interpretation.
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Adaptive and Unconventional Strategies for Engine Knock Control
IEEE Transactions on Control Systems Technology, 2019Co-Authors: Donald Selmanaj, Giulio Panzani, Jonatan Rosgren, Stijn Van Dooren, Christopher H. OnderAbstract:Knock is an undesirable phenomenon affecting the gasoline spark-ignition (SI) Engines. In order to maximize the Engine efficiency and output torque while limiting the Knock rate, the spark timing should be adequately controlled. This brief focuses on the closed-loop Knock control strategies. The proposed control strategies, compared with conventional approaches, show improved performances while remaining simple to use, implement, and tune. First, a deterministic controller that employs a logarithmic increase of the spark timing proves to outperform the conventional strategy in terms of spark timing average and variance. In addition, an adaptive parameter strategy that exploits stochastic information of the process is introduced. Thanks to this extension, the average and the variance of the spark timing are additionally improved while preserving the ease of tuning and the fast reaction times of the deterministic strategy. Throughout this brief, all the Knock controllers are compared with a conventional deterministic strategy and with a recently proposed stochastic one. The advantages of the proposed approaches are confirmed both by simulation and by experimental data collected at a test bench.
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Engine Knock Margin Estimation Using In-Cylinder Pressure Measurements
IEEE ASME Transactions on Mechatronics, 2017Co-Authors: Giulio Panzani, Fredrik Östman, Christopher H. OnderAbstract:Engine Knock is among the most relevant limiting factors in the improvement of the operation of spark-ignited Engines. Due to an abnormal combustion inside the cylinder chamber, it can cause performance worsening or even serious mechanical damage. Being the result of complex local chemical phenomena, Knock turns out to have a significant random behavior but the increasing availability of new on-board sensors permits a deeper understanding of its mechanism. The aim of this paper is to exploit in-cylinder pressure sensors to derive a Knock estimator, based on the logistic regression technique. Thanks to the proposed approach, it is possible to explicitly deal with Knock random variability and to define the so-called margin (or distance ) from the Knocking condition, which has been recently proven to be an effective concept for innovative Knock control strategies. In a model-based estimation fashion, two modeling approaches are compared: one relies on well-known physical mechanisms while the second exploits a principal component analysis to extract relevant pressure information, thus reducing the identification effort and improving the estimation performance.
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CDC - Engine Knock margin control using in-cylinder pressure data: Preliminary results
2017 IEEE 56th Annual Conference on Decision and Control (CDC), 2017Co-Authors: Giulio Panzani, Olga Galluppi, Donald Selmanaj, Sergio M. Savaresi, Jonatan Rosgren, Christopher H. OnderAbstract:Knock is an undesired phenomenon occurring in spark ignited Engines and is controlled acting on the spark timing. This paper presents a closed-loop architecture that makes possible to address the Knock control problem with a standard model-based design approach. An Engine Knock margin estimate is feedback controlled through a PI regulator and its target value is computed starting from the desired Knock probability. A black-box modelling approach is used to identify the dynamics between the spark timing and the Knock margin and a traditional model-based controller synthesis is performed. Experimental results at the test bench show that, compared to a conventional strategy, the proposed approach allows for a better compromise between the controller speed and the variability of the spark timing. Moreover, another advantage w.r.t. the conventional strategies is that closed-loop performance prove to be constant for different reference probabilities, leading to a more regular Engine behaviour.
Fabian Mauss - One of the best experts on this subject based on the ideXlab platform.
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Assessment of the validity of RANS Knock prediction using the resonance theory
International Journal of Engine Research, 2019Co-Authors: Corinna Netzer, Lars Seidel, Frederic Ravet, Fabian MaussAbstract:Following the resonance theory by Bradley and co-workers, Engine Knock is a consequence of an auto-ignition in the developing detonation regime. Their detonation diagram was developed using direct numerical simulations and was applied in the literature to Engine Knock assessment using large eddy simulations. In this work, it is analyzed if the detonation diagram can be applied for post-processing and evaluation of predicted auto-ignitions in Reynolds-averaged Navier–Stokes simulations even though the Reynolds-averaged Navier–Stokes approach cannot resolve the fine structures resolved in direct numerical simulations and large eddy simulations that lead to the prediction of a developing detonation. For this purpose, an Engine operating point at the Knock limit spark advance is simulated using Reynolds-averaged Navier–Stokes and large eddy simulations. The combustion is predicted using the G-equation and the well-stirred reactor model in the unburnt gases based on a detailed gasoline surrogate reaction schem...
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Impact of the surrogate formulation on 3D CFD Engine Knock prediction using detailed chemistry
Fuel, 2019Co-Authors: Corinna Netzer, Lars Seidel, Frederic Ravet, Fabian MaussAbstract:Abstract For Engine Knock prediction, surrogate fuels are often composed of iso-octane and n-heptane since they are the components of the Primary Reference Fuel (PRF). By definition, a PRF has no octane sensitivity (S = RON-MON). However, for a commercial gasoline fuel holds RON > MON and therefor S > 0. More complex surrogates are Toluene Reference Fuels (TRF) and Ethanol containing Toluene Reference Fuels (ETRF). In this work, the impact of the surrogate formulation on the prediction of flame propagation and auto-ignition in the unburnt gases are investigated. The surrogates are composed such that the Research Octane Number is the same. The auto-ignition events ahead of the flame front are predicted using 3D CFD and a combustion model based on the ETRF mechanism by Seidel (2017). The strength of the auto-ignition is determined using the detonation diagram by Bradley and co-workers (2002, 2003). Applying the different surrogates, ignition kernels of different size and reactivity are predicted. The results indicate a dependency on the local temperature history and the low temperature chemistry of the fuel species. The comparison of homogenous constant volume reactor and transient simulations show that the analysis of ignition delay time and octane rating solely from homogenous simulations is not sufficient if the Knock tendency of a surrogate in Engine simulations needs to be characterized.
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Three-dimensional computational fluid dynamics Engine Knock prediction and evaluation based on detailed chemistry and detonation theory:
International Journal of Engine Research, 2017Co-Authors: Corinna Netzer, Lars Seidel, Frederic Ravet, Michal Pasternak, Harry Lehtiniemi, Cathleen Perlman, Fabian MaussAbstract:Engine Knock is an important phenomenon that needs consideration in the development of gasoline-fueled Engines. In our days, this development is supported using numerical simulation tools to furthe...
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Engine Knock Prediction Using Multi Zone Model for Spark Ignition Engines
ASME 2006 Internal Combustion Engine Division Fall Technical Conference (ICEF2006), 2006Co-Authors: Abdelhadi Ahmedi, Rolf Egnell, Ola Stenlåås, Bengt Sundén, Fabian MaussAbstract:Autoignition in SI Engines is an abnormal combustion mode and may lead to Engine Knock in SI Engines. Knock may cause damage and it is a source of noise in Engines. It limits the compression ratio of the Engine and a low compression ratio means low fuel conversion efficiency of the Engine. In this paper a multi zone model based on an existing two zone model Hajireza et al., [1 and 12] and Stenlaas et al., [30] is developed and validated against the experimental results. The validation is done by using the same detailed chemical mechanism consisting of 141 species and about 1405 reactions under the same conditions. The model is a zero dimensional model capable of simulating a full Engine cycle. The two zone combustion model consists of a burned and an unburned zone, separated by a thin adiabatic flame front. The multi zone model differs in the handling of the burned gas. In the multi zone case a number of burned zones are present. The number of zones is decided by the temperature difference between the flame front and the last generated burned zone. The detailed chemical mechanism is taken into account in each zone, while the propagating flame front is calculated from the Wiebe function. Each zone is assumed to be a homogeneous mixture with a uniform temperature, mole and mass fractions of species. The spatial variation of the pressure is neglected, i.e., it is assumed to be the same in the whole combustion chamber at every instant of time. Autoignition is handled by the chemical kinetic model. As the unburned zone is assumed homogeneous the effect of auto ignition is a single pressure peak. The model is not designed to predict the pressure oscillations seen in Engine Knock. Copyright
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Stochastic model for the investigation of the influence of turbulent mixing on Engine Knock
SAE Technical Paper Series, 2004Co-Authors: Adina Gogan, Bengt Sundén, Harry Lehtiniemi, Fabian MaussAbstract:A stochastic model based on a probability density function (PDF) was developed for the investigation of different conditions that determine Knock in spark ignition (SI) Engine, with focus on the turbulent mixing. The model used is based on a two-zone approach, where the burned and unburned gases are described as stochastic reactors. By using a stochastic ensemble to represent the PDF of the scalar variables associated with the burned and the unburned gases it is possible to investigate phenomena that are neglected by the regular existing models (as gas non-uniformity, turbulence mixing, or the variable gas-wall interaction). Two mixing models are implemented for describing the turbulent mixing: the deterministic interaction by exchange with the mean (IEM) model and the stochastic coalescence/ dispersal (C/D) model. Also, a stochastic jump process is employed for modeling the irregularities in the heat transfer. Parameter studies are carried out in order to assess the influence of the turbulence intensity and of the fluctuations in the gas - wall interactions.
Zhi Wang - One of the best experts on this subject based on the ideXlab platform.
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A generalized kinetic model with variable octane number for Engine Knock prediction
Fuel, 2017Co-Authors: Zhi Wang, Wang YingdiAbstract:Abstract A generalized research octane number (GRON) model, including 22 species and 21 reactions, has been developed to simulate the hydrocarbon oxidation with the goal of predicting Engine Knock. The simplicity of the model enables to represent gasoline with different octane numbers by adjusting the global low-temperature reaction rate. The model was validated against shock tube experimental data obtained over a wide range of conditions, including equivalence ratios from 0.5 to 2.0, initial pressures from 13 to 55 bar, and initial temperatures from 700 to 1250 K. Both gasoline Engine Knock and normal combustion were investigated using Computational Fluid Dynamics (CFD) couple with the present GRON. The numerical results proved to be in good agreement with the experimental data. Both the cylinder pressure traces and the distribution of important radical species (CHO and OH) during Knocking combustion can be predicted reasonably well. Compared to the CFD calculations using detailed mechanisms, the generalized kinetic model enables a reduction of the computational time by more than 90%.
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Simulation and experiments of advanced gasoline Engine combustion modes from spark ignition to compression ignition
International Journal of Powertrains, 2017Co-Authors: Zhi Wang, Shijin Shuai, Buyu WangAbstract:This paper reviews some advanced gasoline Engine combustion modes, including direct injection spark ignition (DISI), homogeneous charge compression ignition (HCCI), stratified charge compression ignition (SCCI), and multiple premixed compression ignition (MPCI). To reveal the Engine Knock mechanism of DISI combustion, the flame propagation and pressure oscillation in a boosted gasoline Engine were numerically analysed. To further improve thermal efficiency and reduce emissions, the effects of injection strategies on fuel economy, emissions, and heat release in HCCI combustion were studied. To solve the challenges of ignition control and rapid combustion of HCCI, SCCI and MPCI combustion modes were adopted to achieve high efficiency, low emissions, and low acoustic noise simultaneously.
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Controlled SSCI With Moderate End-Gas Auto-Ignition for Fuel Economy Improvement and Knock Suppression
Journal of Engineering for Gas Turbines and Power, 2015Co-Authors: Hui Liu, Zhi Wang, Jianxin Wang, Mengke Wang, Wanli YangAbstract:Hybrid combustion mode including flame propagation induced by spark ignition (SI) and auto-ignition could be an effective method to improve fuel economy and suppress Engine Knock simultaneously. An experimental research on controlled spark-assisted stratified compression ignition (SSCI) for this purpose was conducted in a gasoline direct injection (GDI) Engine with high compression ratio. At wide open throttle (WOT) and minimum spark advance for best torque (MBT) condition without turbocharging, direct injection was used to form desired stoichiometric stratified mixture while 20% cooled external exhaust gas recirculation (e-EGR) was sucked into the cylinder. The combustion characteristics of controlled SSCI show two-stage heat release, where the first stage is caused by SI and the second stage is due to moderate auto-ignition. Compared with Engine Knock, the second stage heat release of controlled SSCI shows smooth pressure curve without pressure oscillation. This is due to the low energy density mixture around the cylinder wall caused by cooled e-EGR. The stratified mixture could suppress Knock. Fuel economy and combustion characteristics of the baseline and the controlled SSCI combustion were compared. The baseline GDI Engine reaches a maximum of 8.9 bar brake mean effective pressure (BMEP) with brake specific fuel consumption (BSFC) of 291 g/(kWh), and the controlled SSCI combustion achieves a maximum of 8.3 bar BMEP with BSFC of 256 g/(kWh), improving the fuel economy over 12% while maintaining approximately the same power. The results show that controlled SSCI with two-stage heat releases is a potential combustion strategy to suppress Engine Knock while achieving high efficiency of the high compression ratio gasoline Engine.
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Effects of thermodynamic conditions on the end gas combustion mode associated with Engine Knock
Combustion and Flame, 2015Co-Authors: Zhi Wang, Jianxin WangAbstract:Abstract Super-Knock is the main obstacle to improve power density and Engine efficiency of modern gasoline Engines. To understand the mechanism of super-Knock, this study presents an investigation on the end gas combustion process of stoichiometric isooctane/oxygen/nitrogen mixture using a rapid compression machine (RCM), under the thermodynamic conditions close to those of production Engines. The combustion process was captured by simultaneous high speed direct photography and pressure acquisition in the RCM. Three end gas combustion modes: no-auto-ignition, sequential auto-ignition, and detonation under different initial conditions were identified and characterized. The super-Knock in Engine was confirmed to be the result of detonation by comparing the pressure oscillation, thermodynamic state, and pressure rise relative to isochoric combustion with those of detonation observed in the RCM. The experimental results also indicate that the possibility of detonation occurrence increases with increasing initial pressure under the same compression ratio. However, comparing to the pressure, temperature has less effect on detonation formation. It was found that the end gas combustion mode is closely related to the mixture energy density. Generally, as the mixture energy density increases, the end gas combustion mode gradually transits from no-auto-ignition to sequential auto-ignition, and then to detonation. The first auto-ignition spots commonly appear in the mixture near the cylinder wall. The detonation was initiated by near-wall auto-ignition.
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Controlled ASSCI With Moderate Auto-Ignition for Engine Knock Suppression in a GDI Engine With High Compression Ratio
Volume 1: Large Bore Engines; Fuels; Advanced Combustion; Emissions Control Systems, 2014Co-Authors: Hui Liu, Zhi Wang, Jianxin Wang, Mengke Wang, Wanli YangAbstract:This paper presents an experimental study on controlled ASSCI (Assisted Spark Stratified Compression Ignition) for Engine Knock suppression in a GDI Engine with high compression ratio. The direct injection is used for forming desired stoichiometric stratified mixture at WOT condition without turbo-charging. The Engine is filled with 20% cooled external EGR and the ignition timing is maintained at MBT point. The combustion characteristics of the desired stoichiometric stratified mixture show two-stage heat release, where the first stage is caused by spark ignition and the second stage is due to moderate auto-ignition. Compared with Engine Knock, the second stage heat release of controlled ASSCI shows smooth pressure curve without pressure oscillation. This is due to the low energy density mixture around the cylinder wall caused by cooled external EGR. The stratified mixture could suppress Knock. Fuel economy and combustion characteristics of the baseline and the controlled ASSCI combustion were compared. The baseline GDI Engine reaches a maximum of 8.9 bar BMEP with BSFC of 291 g/(kWh), the controlled ASSCI combustion achieves a maximum of 8.3 bar BMEP with BSFC of 256 g/(kWh), improving the fuel economy over 12% while maintaining approximately the same power. CA50 (the crank angle of 50% heat release) of the controlled ASSCI is detected at 8.4° CA ATDC, which is 17.4° CA advanced than that of the baseline while the combustion duration of the controlled ASSCI is 52.84dG CA, 16.6° CA longer than that of the baseline caused by diluted mixture and two-stage heat release. The COV of the controlled ASSCI is 1.4%, 2.1% lower than that of the baseline. The peak pressure (Pmax) and the maximum pressure rise rate (PRRmax) of the controlled ASSCI are 59.7 bar and 2.2 bar/° CA, 22.9 bar and 1.5 bar/° CA higher than that of the baseline respectively. The crank angle of Pmax and PRRmax of the controlled ASSCI are 11° CA ATDC and −1° CA ATDC, 15.4° CA and 17.2° CA earlier than that of the baseline. The results show that controlled ASSCI with two-stage heat releases is a potential combustion strategy to suppress Engine Knock while achieving high efficiency of the high compression ratio gasoline Engine.Copyright © 2014 by ASME
Giulio Panzani - One of the best experts on this subject based on the ideXlab platform.
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Engine Knock detection: an eigenpressure approach
IFAC-PapersOnLine, 2019Co-Authors: Giulio Panzani, Sergio M. Savaresi, Jonatan Rosgren, Gabriele Pozzato, Christopher H. OnderAbstract:Abstract In this work, a Knock detection approach based on in-cylinder pressure principal component analysis is proposed. The introduction of a set of basis functions called eigenpressures used to describe the principal components of the pressure traces allows for an easy and effective separation between the typical “bell shape” component of pressure profiles and the Knock-induced pressure oscillations, making possible the classification of Knocking and not Knocking cycles. The proposed approach is compared to a standard Knock detection method based on the in-cylinder pressure trace band-pass filtering and to a pure data-driven algorithm. The method shows the best Knock classification performances and proves to be advantageous thanks to the low number of easily tunable parameters and their ease of calibration/interpretation.
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Adaptive and Unconventional Strategies for Engine Knock Control
IEEE Transactions on Control Systems Technology, 2019Co-Authors: Donald Selmanaj, Giulio Panzani, Jonatan Rosgren, Stijn Van Dooren, Christopher H. OnderAbstract:Knock is an undesirable phenomenon affecting the gasoline spark-ignition (SI) Engines. In order to maximize the Engine efficiency and output torque while limiting the Knock rate, the spark timing should be adequately controlled. This brief focuses on the closed-loop Knock control strategies. The proposed control strategies, compared with conventional approaches, show improved performances while remaining simple to use, implement, and tune. First, a deterministic controller that employs a logarithmic increase of the spark timing proves to outperform the conventional strategy in terms of spark timing average and variance. In addition, an adaptive parameter strategy that exploits stochastic information of the process is introduced. Thanks to this extension, the average and the variance of the spark timing are additionally improved while preserving the ease of tuning and the fast reaction times of the deterministic strategy. Throughout this brief, all the Knock controllers are compared with a conventional deterministic strategy and with a recently proposed stochastic one. The advantages of the proposed approaches are confirmed both by simulation and by experimental data collected at a test bench.
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Engine Knock Margin Estimation Using In-Cylinder Pressure Measurements
IEEE ASME Transactions on Mechatronics, 2017Co-Authors: Giulio Panzani, Fredrik Östman, Christopher H. OnderAbstract:Engine Knock is among the most relevant limiting factors in the improvement of the operation of spark-ignited Engines. Due to an abnormal combustion inside the cylinder chamber, it can cause performance worsening or even serious mechanical damage. Being the result of complex local chemical phenomena, Knock turns out to have a significant random behavior but the increasing availability of new on-board sensors permits a deeper understanding of its mechanism. The aim of this paper is to exploit in-cylinder pressure sensors to derive a Knock estimator, based on the logistic regression technique. Thanks to the proposed approach, it is possible to explicitly deal with Knock random variability and to define the so-called margin (or distance ) from the Knocking condition, which has been recently proven to be an effective concept for innovative Knock control strategies. In a model-based estimation fashion, two modeling approaches are compared: one relies on well-known physical mechanisms while the second exploits a principal component analysis to extract relevant pressure information, thus reducing the identification effort and improving the estimation performance.
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CDC - Engine Knock margin control using in-cylinder pressure data: Preliminary results
2017 IEEE 56th Annual Conference on Decision and Control (CDC), 2017Co-Authors: Giulio Panzani, Olga Galluppi, Donald Selmanaj, Sergio M. Savaresi, Jonatan Rosgren, Christopher H. OnderAbstract:Knock is an undesired phenomenon occurring in spark ignited Engines and is controlled acting on the spark timing. This paper presents a closed-loop architecture that makes possible to address the Knock control problem with a standard model-based design approach. An Engine Knock margin estimate is feedback controlled through a PI regulator and its target value is computed starting from the desired Knock probability. A black-box modelling approach is used to identify the dynamics between the spark timing and the Knock margin and a traditional model-based controller synthesis is performed. Experimental results at the test bench show that, compared to a conventional strategy, the proposed approach allows for a better compromise between the controller speed and the variability of the spark timing. Moreover, another advantage w.r.t. the conventional strategies is that closed-loop performance prove to be constant for different reference probabilities, leading to a more regular Engine behaviour.
G. Rizzoni - One of the best experts on this subject based on the ideXlab platform.
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Mechanical signature analysis using time-frequency signal processing: application to internal combustion Engine Knock detection
Proceedings of the IEEE, 1996Co-Authors: B. Samimy, G. RizzoniAbstract:Signature analysis consists of the extraction of information from measured signal patterns. The work presented in this paper illustrates the use of time-frequency (TF) analysis methods for the purpose of mechanical signature analysis. Mechanical signature analysis is a mature and developed field; however, TF analysis methods are relatively new to the field of mechanical signal processing, having mostly been developed in the present decade, and have not yet been applied to their full potential in this field of Engineering applications. Some of the ongoing efforts are briefly reviewed in this paper. One important application of TF mechanical signature analysis is the diagnosis of faults in mechanical systems. In this paper we illustrate how the use of joint TF signal representations can result in tangible benefits when analyzing signatures generated by transient phenomena in mechanical systems, such as might be caused by faults or otherwise abnormal operation. This paper also explores signal detection concepts in the joint TF domain and presents their application to the detection of internal combustion Engine Knock.
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Time-frequency analysis for improved detection of internal combustion Engine Knock
Proceedings of IEEE-SP International Symposium on Time- Frequency and Time-Scale Analysis, 1Co-Authors: B. Samimy, G. RizzoniAbstract:Engine Knock has been recognized as a major problem limiting the development of fuel efficient spark-ignition Engines. Detection methods employed in current Knock control systems for spark ignition Engines use a measurement of Engine block vibration tuned to one or more resonance frequencies to extract Knock-related information from the Engine structural vibration. These techniques suffer from poor signal-to-noise ratio (especially at high Engine speed), due to background vibration. It is known that the Engine Knock resonance frequencies vary due to changes in combustion chamber volume and temperature during the expansion phase. Therefore, the authors propose an improved Knock detection method using joint, time-frequency analysis of Engine block vibration and pressure signals. The experimental results for the proposed detection method, show a significant improvement in signal-to-noise ratio (SNR). >