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The major contribution of this paper is to propose a low-cost accurate distance estimation approach. It can potentially be used in driver modelling, accident avoidance and autonomous driving. Based on MATLAB and Python, sensory data from a Continental radar and a monocular dashcam were fused using a Kalman filter. Both sensors were mounted on a Volkswagen Sharan, performing repeated driving on a same route. The established system consists of three components, radar data processing, camera data processing and data fusion using Kalman filter. For radar data processing, raw radar measurements were directly collected from a data logger and analyzed using a Python program. Valid data were extracted and time stamped for further use. Meanwhile, a Nextbase monocular dashcam was used to record corresponding traffic scenarios. In order to measure headway distance from these videos, object depicting the leading vehicle was first located in each frame. Afterwards, the corresponding vanishing point was also detected and used to automatically compute the camera posture, which is to minimize the interference caused by camera vibration. The headway distance can hence be obtained by assuming the leading and host vehicles were in the same ground plane. After both sensory data were obtained, they were synthesized and fused using Kalman filter, to generate a better estimation of headway distance. The performances of both sensors were assessed individually and the correlation between their measurements was evaluated by replotting radar measurements on the video stream. The results of individual sensors and Kalman filter were compared to investigate the optimization performance of the data fusion approach.This is a general guidance of headway distance estimation with a low cost radar and a monocular camera. With described general procedures, this paper can allow researchers to easily fuse radar and camera measurements to obtain optimized headway distance estimation. This paper can facilitate the development of a more realistic robotic driver that can mimic human driver behaviors.

The research described in this paper was aimed at demonstrating the implementation of statistically derived tolerances to so-called ‘noise’ factors that cause imprecision in the vehicle fuel consumption during chassis dynamometer testing. These tolerances were derived from previous work carried out by one of the authors co-workers and were set to achieve a repeatability target of 0.5% coefficient of variation in the vehicle fuel consumption. This target was successfully achieved during a test programme to determine the fuel consumption benefit of two candidate engine oils over production engine oil using a 1.0 l gasoline passenger test vehicle. Regression response modelling was used to determine whether the recorded variability was correlated with the variability in the vehicle fuel consumption and it was found that all the measured test noise factors were adequately controlled. A universal methodology is proposed for the use of the response modelling technique to verify adequate control of known noise factors and to allow for corrections to the vehicle fuel consumption to be performed where factors have not been adequately controlled, without the need to complete additional testing.

In regulated two-stage sequential turbocharging systems, a smaller, high pressure (HP), and a larger, low pressure (LP), turbocharger are sequentially positioned to recover the energy available in the exhaust gases and deliver acceptable level of boost to the intake of an internal combustion engine. Due to the different sizes of the turbochargers, by-pass valves are placed in the system to control operations. Due to the turbocharging system layout, it is clear that the air pressurized by the LP compressor enters non-uniformly the HP compressor. This is caused by the rotating radial compressor and the interconnecting bends which cause swirl and velocity to scatter, respectively. Furthermore, the heat transfer in the two turbochargers may have an effect on the apparent efficiencies. For these reasons, the standard mapping approach for turbochargers is not able to take into account the effect of non-uniform flow and heat transfer. In this paper, a novel approach for mapping the two-stage turbocharging system is proposed and performed into a mono-dimensional simulation code. Although, flow non-uniformity and turbochargers heat transfer effects on the performance of the turbocharging system are not considered, at this present time, the study centralizes on the investigation and the validation of the mapping approach. In fact, a two-stage sequential turbocharging system has been considered for the study and a simulation code to investigate the mapping technique has been implemented.

Engine downsizing, which is the use of a smaller engine that provides the power of a larger engine, is now considered a mega-trend for the internal combustion engine market. It is usually achieved using one or more boosting devices including a supercharger or a turbocharger. Although supercharging is beneficial for engine’s transient response, turbocharging technology is more widely adopted considering its advantages in fuel efficiency. Compared to turbocharged compression ignition engines, turbocharged spark-ignition engines tend to be more challenging with respect to the gas exchange process mainly due to their higher pumping loss, the need for throttling and the fact that spark-ignition engines demand more controllability due to the mitigation of knock, particularly with regard to minimizing trapped residuals. These challenges encourage the entire gas exchange process of turbocharged spark-ignition engines to be regarded as a complete air management system instead of just looking at the boosting system in isolation. In addition, more research emphasis should be focused on novel approaches to improve the gas exchange process of downsized turbocharged spark-ignition engines because the refinement of the conventional technologies cannot provide continuous gains indefinitely and only innovative concept may improve the engine performance to meet the fuel efficiency target and the more stringent emission regulation in the future. This article will first briefly review knowledge of the current state of the art technologies that are in production as opposed to approaches that are currently only being investigated at a research level. Next, more novel methods of the gas exchange process are introduced to identify the improved synergies between the engine and the boosting machine. The major findings to improve the gas exchange process that emerge from this review comprise four aspects (depending on the location where the novel technologies are implemented) which are as follows: charge air pressurization/de-pressurization improvement, combustion efficiency enhancement within the chamber, valve event–associated development and exhaust system optimization. Although the interaction between these technologies on different aspects of the gas exchange process was found to be highly complex, the optimization or the combination of these technologies is anticipated to further improve a downsized turbocharged spark-ignition engine’s performance.

As electric hybrid powertrains become more widely adopted in passenger vehicles, a variety of electric machine and internal combustion engine architectures has been developed to meet diverse requirements. Research suggests that less than 20 percent of daily driving mileages are over 70 km but that longer trips are relatively common. This fact makes the range extended electric vehicle (REEV) potentially more favourable to typical family usage. To fulfil an everyday full electric commute a smaller battery pack can be used, which reduces cost. An on-board auxiliary power unit (APU) is designed to recharge the batteries for occasional long range trips. Usually, a low-cylinder-count small capacity engine coupled with an electric generator is used in the APU. However, this type of engine inherently exposes the system to more severe torque pulsations due to the lower firing frequency. This is not desirable for intermittent APU operation. The noise and vibration could be noticeable to the passengers once the APU starts running. The torque output of a synchronous electric machine can be accurately controlled by the invertor through vector control theory. Thus, it is feasible to dynamically vary the generator in-cycle torque pattern to counteract the engine torque oscillation. Consequently, a smoother operation is achievable. In this paper, a series of motor/generator control torque patterns were applied to cancel the engine in-cycle torque pulsations. The correlation between the electric machine torque profile and the engine in-cycle speed variation was investigated. As more aggressively use of the electric machine was made to achieve better system operation characteristic, the electric losses become more significant compared to constant torque demand strategies as does the thermal impact. Therefore, the electric losses and thermal effect were also studied for a given motor/generator design when a dynamic torque control strategy is deployed.

The paper details improvements in the technique used to locate the boundary of the permissible operating envelope (or limit space) of an engine. This process is an important step in the model-based calibration of engines and is currently conducted manually or using cautious automatic search algorithms because of the risks to engine integrity if operating limits are exceeded. To improve this process, prior knowledge was used to mimic the behaviour of an expert calibrator following two strategies. The first was designed to offer a rapid search based on a similar premise to commercially available tools. The second scheme offers a thorough search of the limit space using a scheme that targets the extremes of the operating envelope. Both patterns were enhanced using prior knowledge generated from previous operating points in order to speed up the search. When implemented on the test bed the use of prior knowledge in this way has shown the potential to shorten the search time by up to 25 per cent. The thorough search pattern increased the accuracy of the limit space definition by up to 40 per cent but resulted in a significantly slower search.

Cyclic variability (CV) in combustion has been studied over many years and is still an active area of research. Despite the application of many analytical tools, including, in more recent years, those connected with the study of non-linear dynamic systems, CV remains a challenging subject. In the past, most researchers into CV have presented their findings in the form of overall statistical measures. However, it is felt that perhaps more attention needs to be paid to sequences of combustion cycles on a detailed cycle-to-cycle basis, particularly where the aim is to try to formulate a control mechanism to reduce CV, and that sonification combined with self-similarity plots provides a useful tool to facilitate such an approach. The purpose of this paper is to introduce sonification to automotive engineers, who may be unfamiliar with it, and to give an example of its implementation and application in the study of CV in internal combustion engines.

This paper describes the development of an exhaust system model based on the characterization of heat transfer in a series of 11 test sections designed to represent a range of configurations seen in production exhaust systems. These sections include variations in the wall thickness, diameter, bend angle, and radius. This work is part of a larger activity aimed at the accurate modelling of heat transfer and subsequent catalyst light-off in production exhaust systems consisting of similar geometries. For each section a range of steady state tests was performed on a dynamic test cell using a port injected gasoline engine. In each case a correlation between the observed Reynolds number Re and the Nusselt number Nu was developed. A model of the system was implemented in MATLAB—Simulink in which each pipe element was split into 25 subelements by dividing the pipe into five, both axially and radially. After each individual section had been characterized, a generic model was built that was capable of determining the relationship between the Nusselt number and the Reynolds number for previously unseen pipe geometries. Complex exhaust systems can be constructed from smaller elements of defined geometry. The modelling approach was validated using experimental data gathered from vehicle testing on a chassis dynamometer. The steady state relationship between Re and Nu allows heat transfer in the test section to be predicted over transient test cycles and demonstrates good agreement with relationships in the literature.

This paper describes the characterization of heat transfer in a series of 11 test sections designed to represent a range of configurations seen in production exhaust systems, which is part of a larger activity aimed at the accurate modelling of heat transfer and subsequent catalyst light-off in production exhaust systems comprised of similar geometries. These sections include variations in wall thickness, diameter, bend angle and radius. For each section a range of transient and steady state tests were performed on a dynamic test cell using a port-injected gasoline engine. In each case a correlation between observed Reynolds number (Re) and Nusselt number (Nu) was developed. A model of the system was implemented in Matlab/Simulink in which each pipe element was split into 25 sub-elements by dividing the pipe into five both axially and radially. The modelling approach was validated using the experimental data. The steady state relationship between Re and Nu allow heat transfer in the test section to be predicted with acceptable accuracy over transient test cycles and demonstrates good agreement with relationships in the literature. The model accuracy was enhanced by developing empirical models of heat transfer during the warm-up stage of the transient test.

The adoption of two stage serial turbochargers in combination with internal combustion engines can improve the overall efficiency of powertrain systems. In conjunction with the increase of engine volumetric efficiency, two stage boosting technologies are capable of increasing torque and pedal response of small displacement engines. In two stage serial turbocharges, a high pressure (HP) and a low pressure (LP) turbocharger are connected by a series of ducts. The former can increase charge pressure for low air mass flow typical of low engine speed. The latter has a bigger size and can cooperate with higher mass flows. In serial configuration, turbochargers are packaged in a way that the exhaust gases access the LP turbine after exiting the HP turbine. On the induction side, fresh air is compressed sequentially by LP and HP compressors. By-pass valves and waste-gated turbines are often included in two stage boosting systems in order to regulate turbochargers operations. One-dimensional modelling approaches are considered for investigating the integration of boosting systems with internal combustion engines. In this scenario, turbocharger behaviour are input in the powertrain models through previously measured compressor and turbine maps in turbocharger gas stands. However, this procedure does not capture all the effects that occur on engine application such as heat transfer, friction and flow motion that influence the turbochargers operations. This is of particular importance for two stage serial turbochargers where the LP compressor may induce a swirling motion to the flow at the entry of the HP compressor. In addition, flow non-uniformities caused by bends between the two compressors can make the HP compressor perform differently. In this paper, a review of the available literature containing approaches to quantify the effects of heat transfer on turbocharger efficiency and the flow influence in the prediction of two stage serial turbochargers performance is explored.

One of the most promising methods to reduce vehicle fuel consumption and CO2 emissions is by using an electric motor in the vehicle powertrain system to assist the internal combustion engine, or propel vehicle by itself. This paper discusses a new potential method to improve axial flux motor performance and efficiency, by dynamically changing the air gap between the rotor and the stator. A series of experiments have provided insight into how certain key characteristics of the variable air gap (VAG) across a wide range of air gap settings. The results show that, on increasing the air gap from the normal 1.2mm to as much as 18mm, the peak torque reduces from 72Nm to 16Nm while the maximum speed of the motor increases from 5500rev/min to over 7000rev/min. It was seen that the high efficiency region moves towards the higher speed region as the air gap increases. Also, on increasing the air gap, the motor had a higher torque output at high speed. This behaviour is of limited benefit in a fixed geometry design, but the implementation of a software controlled air gap design allows the motor characteristics to be varied to suit the prevailing operating conditions. To demonstrate this benefit, the experimental data were used to build a model of the motor with a dynamically variable air gap concept incorporated into it. This model was then used with a fixed ratio powertrain, combined with a simple vehicle model and exercised over the NEDC drive cycle to predict the savings it would achieve when compared to a standard electric motor of similar technical specifications. The model predicts the overall battery energy usage reduced by 0.72% when using a VAG design. In addition, the VAG concept has the potential to reduce gearbox complexity and provide better drivability at higher speeds over the standard motor.

European regulations set the emissions requirements for new vehicles at 130 g CO2/km, with an additional 10 g CO2/km to be achieved by additional complementary measures, including gear shift indicators. However, there is presently little knowledge of how much fuel or CO2 could actually be saved by the introduction of gear shift indicators, and there is no consensus on how these savings should be quantified. This study presents a procedure which allows these savings to be quantified over a New European Driving Cycle, and explores the trade-off between fuel savings and drivability. A vehicle model was established and calibrated using data obtained from pedal ramp tests conducted at steady speed using a chassis dynamometer, significantly reducing the time required to generate a calibration data set when compared with a steady-state mapping approach. This model was used for the optimisation of gear shift points on the New European Driving Cycle for reduced fuel consumption subject to drivability constraints. During model validation the greatest fuel saving achieved experimentally for a warm engine was 3.6% over the New European Driving Cycle, within the constraints imposed using subjective driver appraisal of vehicle drivability. The same shift strategy for a cold start driving cycle showed a fuel saving of 4.3% over the baseline, with corresponding savings in CO2 of 4.5% or 6.4 g CO2/km. For both hot and cold tests the savings were made entirely in the urban phase of the New European Driving Cycle; there were no significant differences in fuel consumption in the extra-urban phase. These results suggest that the introduction of gear shift indicators could have a substantial impact, contributing significantly towards the 10 g CO2/km to be achieved by additional complementary measures when assessed in this way. It is not clear whether these savings would translate into real world driving conditions, but for legislative purposes an assessment procedure based on the New European Driving Cycle remains a logical choice for simplicity and continuity.

The research described in this paper was aimed at determining any common precedents for abnormal combustion events in a gasoline engine in order that their occurrence might be predicted and ultimately corrected. Combustion data was collected for 1200 cycles from a motorbike spark ignition engine running at 4,000rpm and 1.15 bar BMEP at fuelling conditions ranging from rich through stoichiometric to lean. The least cyclic variability occurred during slightly rich fuelling and was best characterised through the heat released per cycle. Phase-lag plots of the heat released per cycle showed boomerang shaped patterns, indicating deterministic cyclic variability. This suggested that an algorithm capable of predicting poor cycles could be developed. It was found, however, that the majority of poor combustion events are preceded by cycles of an approximately average heat release and that poor combustion events are likely to be followed by a strong combustion event. Importantly not all poor cycles follow this pattern. This means that existing prediction algorithms which are based on preceding cycles would not be suitable in this case. An examination of the chain length of good or average combustion events between poor events did not show any chain length commonality across the AFR’s. The findings of this paper support the view that the deterministic patterns in the cyclic variations in combustion are present but that they are complex and cannot be predicted using simple metrics based on neighbouring cycles. A more thorough understanding of the fundamental contribution of previous combustion cycles to the variability is required for predictive tools to be effective.

This paper describes the further development of an exhaust system model based on the experimental characterization of heat transfer in a series of different pipe sections. Building on previous work published in this journal by the present authors, this study was undertaken to improve the operating range, accuracy, and usability of the original model as well as to introduce the ability to model twin-skin exhaust sections with an air gap. Convective heat transfer relationships for nine stainless steel exhaust bend sections of various wall thicknesses and radii were experimentally characterized over a range of steady state conditions. In each case a correlation between the observed Reynolds number Re and the Nusselt number Nu was developed. Based on measured experimental data, a generic model was built using MATLAB/Simulink; this model is capable of predicting the relationship between the Nusselt number and the Reynolds number for previously unseen pipe geometries falling within the experimental design range. To develop the usefulness of the model further, 15 twin-skin test sections, intended to represent a range of geometries applicable to production automotive gasoline exhaust systems, were also fabricated and characterized. Within the model, both skins of each pipe section were split into five axial elements and five radial elements with the inner and outer skins linked via the modelling of free convection and radiation between them. The predicted Reynolds–Nusselt relationships for each bend section and twin-skin configuration were validated using transient experimental data over a portion of the US06 drive cycle. The final model demonstrated an improved accuracy of exhaust gas temperature predictions, compared with the previous model iterations, with typical errors of less than ±1 per cent and a mean error over the US06 cycle of +0.2 per cent.

Improving engine warm up time is of great interest because cold start engines suffer from increased fuel consumption. This study comprises of two phases: the first looking at global benefits from a novel engine cooling system incorporating coolant flow control valves and dual EGR setup. The new cooling system showed promising signs of influencing energy flows during warm up, however only limited analysis was possible. The second phase used an instrumented engine to show new ways of quantifying performance enhancements through combustion chamber heat transfer, local bearing oil film temperatures and bearing heat transfer. 1 dimensional heat transfer analysis demonstrated the significant energy required to warm up the engine structure and 25~50kJ heat loss per main crank shaft bearing.

This paper describes the development and automated calibration of a compact analytically based model of the wall-wetting phenomenon of modern port fuel-injected (PFI) spark-ignition (SI) gasoline engines. The wall-wetting model, based on the physics of forced convection with phase change, is to be used in an automated model-based calibration program. The first stage of work was to develop a model of the wall-wetting phenomenon in Matlab. The model was then calibrated using experimental data collected from a 1.8-litre turbocharged I4 engine coupled to a dynamic 200kW AC dynamometer. The calibration was accomplished by adopting a two stage optimization approach. Firstly, a design of experiments (DoE) approach was used to establish the effect of the principal model parameters on a set of metrics that characterized the magnitude and duration of the measured lambda deviation during a transient. This DoE was used to identify the region in which the best calibration for the model was located. Secondly, the calibration was refined using an automated iterative script which estimated new settings for the model parameters with the target of minimizing the error between measured and simulated lambda traces. The model developed is able to accurately predict the magnitude and duration of lambda excursions during transient events. Furthermore the model is capable of representing the change in lambda excursions arising from variations in ambient conditions.