Richard Stobart - Academia.edu (original) (raw)

Papers by Richard Stobart

Proceedings of the 2nd international conference on Industrial and engineering applications of artificial intelligence and expert systems - Volume 1

Advances in Mechanical Engineering

To meet rising demands in performance and emissions compliance, companies are driven to develop s... more To meet rising demands in performance and emissions compliance, companies are driven to develop systems of ever-increasing complexity. In-the-loop methods use a hybrid approach combining a physical subsystem with a virtual subsystem in real-time that can make product development processes faster and cheaper, enabling physical subsystems to be tested in real-world conditions while they are immersed in virtual environment simulation. These techniques evolved from being used solely in controller development with only the embedded controller placed as hardware-in-the-loop (HIL), to being a more holistic technique for system synthesis, capable of both component- and system-level studies. This paper delves into the development of the latter form, henceforth referred to as ‘component-in-the-loop’ or CIL. It provides a literature review of the growing uses of the technique in automotive development, giving a general implementation guidance in system architecture, methodology and control sys...

2007 European Control Conference (ECC)

In this paper, an optimal nonlinear control technique based on the analytic solution of a perform... more In this paper, an optimal nonlinear control technique based on the analytic solution of a performance index is used to derive a controller for the Diesel engine air system. The control objective is to achieve tracking of suitable references (corresponding to low emissions) for the air-fuel ratio and the fraction of the recirculated exhaust gas. The considered Diesel engine is a medium duty Caterpillar 3126B with six cylinders equipped with a variable geometry turbocharger and an exhaust gas recirculation valve. The proposed controller is designed on the reduced third order mean value model and implemented as a closed-form nonlinear model predictive control law on the full order model. In order to eliminate steady state offset, integral action is introduced. The resulting controllers, with and without integral action, are assessed through simulations with a SIL architecture using dSpace Simulator. The controller with integral action, exhibits good control performance, with zero offset and ensures global stability and tracking of output references.

Professional Engineering Press, Apr 19, 2004

About the Editors.Preface.Vehicle Dynamics and Control.Vehicle Safety.Human-Centered Design.Devel... more About the Editors.Preface.Vehicle Dynamics and Control.Vehicle Safety.Human-Centered Design.Developing Vehicle Propulsion for the Environment.Vehicle Design.Experimental Techniques.Control Systems Technology.Author's Index.

2016 IEEE 55th Conference on Decision and Control (CDC), 2016

Electrified turbocharger is a critical technology for engine downsizing and is a cost-effective s... more Electrified turbocharger is a critical technology for engine downsizing and is a cost-effective solution for exhaust gas energy recovery. In conventional turbocharged diesel engines, the air path holds strong nonlinearity since the actuators are all driven by the exhaust gas. In an electrified turbocharged diesel engine (ETDE), the coupling is more complex, due to the electric machine mounted on the turbine shaft impacts the exhaust manifold dynamics as well. In distributed single-input singleoutput control methods, the gains tuning is time consuming and the couplings are ignored. To control the performance variables independently, developing a promising multi-input multi-output control method for the ETDE is essential. In this paper, a modelbased multi variable robust controller is designed to control the performance variables in a systematic way. Both simulation and experimental results verified the effectiveness of the proposed controller.

Authoritative account of recent developments in thermoelectric materials and devices for power en... more Authoritative account of recent developments in thermoelectric materials and devices for power energy harvesting applications, ideal for researchers and industrialists in materials science.

In modern process and power plant the cost of installation demands operation at peak efficiency f... more In modern process and power plant the cost of installation demands operation at peak efficiency for prolonged periods. This places significant demands on the control and monitoring systems to keep efficiency high while giving significant warning of a drop in efficiency or a component failure. We present an approach to process monitoring based on Qualitative Models which are used as a framework in which a range of monitoring techniques are located. The methods are described in the context of diagnosing faults in a heat exchanger. We present an application based on a Cogeneration scheme which highlights many of the issues in process monitoring.

IEEE Transactions on Industrial Electronics, 2020

The electric turbocharger is a promising solution for engine downsizing. It provides great potent... more The electric turbocharger is a promising solution for engine downsizing. It provides great potential for vehicle fuel efficiency improvement. The electric turbocharger makes engines run as hybrid systems so critical challenges are raised in energy management and control. This paper proposes a real-time energy management strategy based on updating and tracking of the optimal exhaust pressure setpoint. Starting from the engine characterisation, the impacts of the electric turbocharger on engine response and exhaust emissions are analysed. A multivariable explicit model predictive controller is designed to regulate the key variables in the engine air system, while the optimal setpoints of those variables are generated by a high level controller. The two-level controller works in a highly efficient way to fulfill the optimal energy management. This strategy has been validated in physical simulations and experimental testing. Excellent tracking performance and sustainable energy management demonstrate the effectiveness of the proposed method. Index Terms-Electric turbocharger, real-time energy management, explicit model predictive control Dezong Zhao (M'12-SM'17) received the B.S. and M.S. degrees in control science and engineering from the

IEEE Transactions on Industrial Electronics, 2018

Electrical turbocharger assist is one of the most critical technologies in improving fuel efficie... more Electrical turbocharger assist is one of the most critical technologies in improving fuel efficiency of conventional powertrain vehicles. However, strong challenges lie in high efficient operations of the device due to its complexity. In this paper, an integrated framework on characterization, control, and testing of the electrical turbocharger assist is proposed. Starting from a physical characterization of the engine, the controllability and the impact of the electrical turbocharger assist on fuel economy and exhaust emissions are both analyzed. A multivariable robust controller is designed to regulate the dynamics of the electrified turbocharged engine in a systematic approach. To minimize the fuel consumption in real time, a supervisory level controller is designed to update the setpoints of key controlled variables in an optimal way. Furthermore, a cutting-edge experimental platform based on a heavy-duty diesel engine is built. The proposed framework has been evaluated in simulations, physical simulations, and experiments. Results are presented for the developed system and the proposed framework that demonstrate excellent tracking performance, high robustness, and the potential for improvements in fuel efficiency. Index Terms-Electrical turbocharger assist (ETA), multivariable control, real-time energy management, system characterization, testing framework design. NOMENCLATURE GHG Greenhouse gas. EM Electrical machine. ETA Electrical turbocharger assist. TDE Turbocharged diesel engine. ETDE Electrified turbocharged diesel engine.

SAE Technical Paper Series, 2018

Applied Energy, 2019

Developed and validated a bifunctional thermoelectric module model. • Four-quadrant operation dia... more Developed and validated a bifunctional thermoelectric module model. • Four-quadrant operation diagram was developed to present the bidirectional characteristic of module. • Case study of applying a bifunctional thermoelectric generator to a 2 l-diesel engine was carried out. • Faster warm-up effect of engine oil can be obtained by a bifunctional thermoelectric generator.

International Journal of Powertrains, 2016

A control-oriented, low computational cost nitrogen oxides emissions model for a diesel engine is... more A control-oriented, low computational cost nitrogen oxides emissions model for a diesel engine is presented. The model is based on zero-dimensional one-zone nitric oxide formation thermodynamics. The main inputs to the model are measured cylinder pressure, engine speed and manifold air flow rate. As only three model parameters are required, the calibration effort is minor. Instead of solving nonlinear equations to obtain the oxygen concentration from dissociation reactions, a simple estimation method used the estimated number of moles in the burned zone. The model was validated using engine data and show that the model can predict emissions with high accuracy as they vary with load, start of injection, fuel rail pressure and exhaust gas recirculation rate. As there are few, relatively simple algorithms involved, this model can easily be implemented online. It also has potential to be used in the control of both exhaust after-treatment and the engine combustion process.

SAE Technical Paper Series, 2017

IFAC-PapersOnLine, 2016

The electrification of engine components offers significant opportunities for fuel economy improv... more The electrification of engine components offers significant opportunities for fuel economy improvements, including the use of an electrified turbocharger for engine downsizing and exhaust gas energy recovery. By installing an electrical device on the turbocharger, the excess energy in the air system can be captured, stored, and re-used. This new configuration requires a new control structure to manage the air path dynamics. The selection of optimal setpoints for each operating point is crucial for achieving the full fuel economy benefits. In this paper, a control-oriented model for an electrified turbocharged diesel engine is analysed. Based on this model, a structured approach for selecting control variables is proposed. A model-based multi-input multi-output decoupling controller is designed as the low level controller to track the desired values and to manage internal coupling. An equivalent consumption minimization strategy is employed as the supervisory level controller for real-time energy management. The supervisory level controller and low level controller work together in a cascade which addresses both fuel economy optimization and battery state-of-charge maintenance. The proposed control strategy has been successfully validated on a detailed physical simulation model.

IFAC-PapersOnLine, 2016

This paper presents that the dwell time between two consequent injection pulses of a diesel engin... more This paper presents that the dwell time between two consequent injection pulses of a diesel engine that is equipped with a common rail fuel injection system has big impact on the combustion process. It is because the change of dwell time has influence on the injection pressure for the next injection. This phenomenon was then used in implementing a Indicated Mean Effective Pressure (IMEP) closed-loop control system to reduce the cycleto-cycle combustion variations. The injected fuel quantity based IMEP closed-loop control system was also implemented and tested on the test diesel engine. Its disturbance rejection ability has been experimentally investigated to confirm that with this IMEP closed-loop control, diesel engine has strong disturbance rejection ability which implies that a speed governor with IMEP closed-loop control being the inner loop will improve engine speed control performance. Such two-loop speed control system was implemented and tested on the test engine in the lab. The inner IMEP closed-loop control for each cylinder has the same setpoint value which was calculated from the outer loop speed controller. This will increase the combustion consistency among all cylinders.

Applied Thermal Engineering, 2017

With the introduction of carbon dioxide emissions legislation for vehicles, the pressure on fuel ... more With the introduction of carbon dioxide emissions legislation for vehicles, the pressure on fuel efficiency in vehicle propulsion systems has grown significantly. Cost-effective efficiency improvements have become the topic of intensive research efforts. Amongst such efficiency measures, waste heat recovery (WHR) has attracted a deep interest both in the industrial and academic sectors. As a potentially low maintenance solid-state implementation, the thermo-electric generator (TEG) represents a promising candidate technology. Thermoelectric (TE) solutions, compared with other WHR methods have an appealing simplicity that could translate rapidly into robust engineering solutions. Achieving competitive efficiencies and low manufacturing cost however remains a substantial research challenge. Critical to progress are modelling processes that allow solutions to be formulated and assessed. The work reported in this paper demonstrates that a modelling process that makes use of mainstream computational fluid dynamics (CFD) codes is feasible. A benchmark TEG design first simulated and then run on an engine test bed showed agreement between simulation and experiment to within 10%. Closed form results for the optimised performance of module and overall TEG design have been reported in the literature and lend important insights into implementation methods. However practical implementation must take account of varying conditions and spatial variations in the heat exchange process. A CFD code that would permit a detailed evaluation TEG parameters and material properties has been demonstrated with a plate fin design of heat exchanger. Meanwhile a simpler model has achieved agreement to within 12% with the CFD code indicating that a rapid modelling process is feasible and could support new "in the loop" test techniques.

SAE Technical Paper Series, 2017

Thermoelectric generator (TEG) has received more and more attention in its application in the har... more Thermoelectric generator (TEG) has received more and more attention in its application in the harvesting of waste thermal energy in automotive engines. Even though the commercial Bismuth Telluride thermoelectric material only have 5% efficiency and 250°C hot side temperature limit, it is possible to generate peak 1kW electrical energy from a heavy-duty engine. If being equipped with 500W TEG, a passenger car has potential to save more than 2% fuel consumption and hence CO2 emission reduction. TEG has advantages of compact and motionless parts over other thermal harvest technologies such as Organic Rankine Cycle (ORC) and Turbo-Compound (TC). Intense research works are being carried on improving the thermal efficiency of the thermoelectric materials and increasing the hot side temperature limit. Future thermoelectric modules are expected to have 10% to 20% efficiency and over 500°C hot side temperature limit. This paper presents the experimental synthesis procedure of both p-type and n-type skutterudite thermoelectric materials and the fabrication procedure of the thermoelectric modules using this material. These skutterudite materials were manufactured in the chemical lab in the University of Reading and then was fabricated into modules in the lab in Cardiff University. These thermoelectric materials can work up to as high as 500°C temperature and the corresponding modules can work at maximum 400°C hot side temperature. The performance loss from materials to modules has been investigated and discussed in this paper. By using a validated TEG model, the performance improvement using these modules has been estimated compared to commercial Bisemous Telluride modules.

Proceedings of the 2nd international conference on Industrial and engineering applications of artificial intelligence and expert systems - Volume 1

Advances in Mechanical Engineering

To meet rising demands in performance and emissions compliance, companies are driven to develop s... more To meet rising demands in performance and emissions compliance, companies are driven to develop systems of ever-increasing complexity. In-the-loop methods use a hybrid approach combining a physical subsystem with a virtual subsystem in real-time that can make product development processes faster and cheaper, enabling physical subsystems to be tested in real-world conditions while they are immersed in virtual environment simulation. These techniques evolved from being used solely in controller development with only the embedded controller placed as hardware-in-the-loop (HIL), to being a more holistic technique for system synthesis, capable of both component- and system-level studies. This paper delves into the development of the latter form, henceforth referred to as ‘component-in-the-loop’ or CIL. It provides a literature review of the growing uses of the technique in automotive development, giving a general implementation guidance in system architecture, methodology and control sys...

2007 European Control Conference (ECC)

In this paper, an optimal nonlinear control technique based on the analytic solution of a perform... more In this paper, an optimal nonlinear control technique based on the analytic solution of a performance index is used to derive a controller for the Diesel engine air system. The control objective is to achieve tracking of suitable references (corresponding to low emissions) for the air-fuel ratio and the fraction of the recirculated exhaust gas. The considered Diesel engine is a medium duty Caterpillar 3126B with six cylinders equipped with a variable geometry turbocharger and an exhaust gas recirculation valve. The proposed controller is designed on the reduced third order mean value model and implemented as a closed-form nonlinear model predictive control law on the full order model. In order to eliminate steady state offset, integral action is introduced. The resulting controllers, with and without integral action, are assessed through simulations with a SIL architecture using dSpace Simulator. The controller with integral action, exhibits good control performance, with zero offset and ensures global stability and tracking of output references.

Professional Engineering Press, Apr 19, 2004

About the Editors.Preface.Vehicle Dynamics and Control.Vehicle Safety.Human-Centered Design.Devel... more About the Editors.Preface.Vehicle Dynamics and Control.Vehicle Safety.Human-Centered Design.Developing Vehicle Propulsion for the Environment.Vehicle Design.Experimental Techniques.Control Systems Technology.Author's Index.

2016 IEEE 55th Conference on Decision and Control (CDC), 2016

Electrified turbocharger is a critical technology for engine downsizing and is a cost-effective s... more Electrified turbocharger is a critical technology for engine downsizing and is a cost-effective solution for exhaust gas energy recovery. In conventional turbocharged diesel engines, the air path holds strong nonlinearity since the actuators are all driven by the exhaust gas. In an electrified turbocharged diesel engine (ETDE), the coupling is more complex, due to the electric machine mounted on the turbine shaft impacts the exhaust manifold dynamics as well. In distributed single-input singleoutput control methods, the gains tuning is time consuming and the couplings are ignored. To control the performance variables independently, developing a promising multi-input multi-output control method for the ETDE is essential. In this paper, a modelbased multi variable robust controller is designed to control the performance variables in a systematic way. Both simulation and experimental results verified the effectiveness of the proposed controller.

Authoritative account of recent developments in thermoelectric materials and devices for power en... more Authoritative account of recent developments in thermoelectric materials and devices for power energy harvesting applications, ideal for researchers and industrialists in materials science.

In modern process and power plant the cost of installation demands operation at peak efficiency f... more In modern process and power plant the cost of installation demands operation at peak efficiency for prolonged periods. This places significant demands on the control and monitoring systems to keep efficiency high while giving significant warning of a drop in efficiency or a component failure. We present an approach to process monitoring based on Qualitative Models which are used as a framework in which a range of monitoring techniques are located. The methods are described in the context of diagnosing faults in a heat exchanger. We present an application based on a Cogeneration scheme which highlights many of the issues in process monitoring.

IEEE Transactions on Industrial Electronics, 2020

The electric turbocharger is a promising solution for engine downsizing. It provides great potent... more The electric turbocharger is a promising solution for engine downsizing. It provides great potential for vehicle fuel efficiency improvement. The electric turbocharger makes engines run as hybrid systems so critical challenges are raised in energy management and control. This paper proposes a real-time energy management strategy based on updating and tracking of the optimal exhaust pressure setpoint. Starting from the engine characterisation, the impacts of the electric turbocharger on engine response and exhaust emissions are analysed. A multivariable explicit model predictive controller is designed to regulate the key variables in the engine air system, while the optimal setpoints of those variables are generated by a high level controller. The two-level controller works in a highly efficient way to fulfill the optimal energy management. This strategy has been validated in physical simulations and experimental testing. Excellent tracking performance and sustainable energy management demonstrate the effectiveness of the proposed method. Index Terms-Electric turbocharger, real-time energy management, explicit model predictive control Dezong Zhao (M'12-SM'17) received the B.S. and M.S. degrees in control science and engineering from the

IEEE Transactions on Industrial Electronics, 2018

Electrical turbocharger assist is one of the most critical technologies in improving fuel efficie... more Electrical turbocharger assist is one of the most critical technologies in improving fuel efficiency of conventional powertrain vehicles. However, strong challenges lie in high efficient operations of the device due to its complexity. In this paper, an integrated framework on characterization, control, and testing of the electrical turbocharger assist is proposed. Starting from a physical characterization of the engine, the controllability and the impact of the electrical turbocharger assist on fuel economy and exhaust emissions are both analyzed. A multivariable robust controller is designed to regulate the dynamics of the electrified turbocharged engine in a systematic approach. To minimize the fuel consumption in real time, a supervisory level controller is designed to update the setpoints of key controlled variables in an optimal way. Furthermore, a cutting-edge experimental platform based on a heavy-duty diesel engine is built. The proposed framework has been evaluated in simulations, physical simulations, and experiments. Results are presented for the developed system and the proposed framework that demonstrate excellent tracking performance, high robustness, and the potential for improvements in fuel efficiency. Index Terms-Electrical turbocharger assist (ETA), multivariable control, real-time energy management, system characterization, testing framework design. NOMENCLATURE GHG Greenhouse gas. EM Electrical machine. ETA Electrical turbocharger assist. TDE Turbocharged diesel engine. ETDE Electrified turbocharged diesel engine.

SAE Technical Paper Series, 2018

Applied Energy, 2019

Developed and validated a bifunctional thermoelectric module model. • Four-quadrant operation dia... more Developed and validated a bifunctional thermoelectric module model. • Four-quadrant operation diagram was developed to present the bidirectional characteristic of module. • Case study of applying a bifunctional thermoelectric generator to a 2 l-diesel engine was carried out. • Faster warm-up effect of engine oil can be obtained by a bifunctional thermoelectric generator.

International Journal of Powertrains, 2016

A control-oriented, low computational cost nitrogen oxides emissions model for a diesel engine is... more A control-oriented, low computational cost nitrogen oxides emissions model for a diesel engine is presented. The model is based on zero-dimensional one-zone nitric oxide formation thermodynamics. The main inputs to the model are measured cylinder pressure, engine speed and manifold air flow rate. As only three model parameters are required, the calibration effort is minor. Instead of solving nonlinear equations to obtain the oxygen concentration from dissociation reactions, a simple estimation method used the estimated number of moles in the burned zone. The model was validated using engine data and show that the model can predict emissions with high accuracy as they vary with load, start of injection, fuel rail pressure and exhaust gas recirculation rate. As there are few, relatively simple algorithms involved, this model can easily be implemented online. It also has potential to be used in the control of both exhaust after-treatment and the engine combustion process.

SAE Technical Paper Series, 2017

IFAC-PapersOnLine, 2016

The electrification of engine components offers significant opportunities for fuel economy improv... more The electrification of engine components offers significant opportunities for fuel economy improvements, including the use of an electrified turbocharger for engine downsizing and exhaust gas energy recovery. By installing an electrical device on the turbocharger, the excess energy in the air system can be captured, stored, and re-used. This new configuration requires a new control structure to manage the air path dynamics. The selection of optimal setpoints for each operating point is crucial for achieving the full fuel economy benefits. In this paper, a control-oriented model for an electrified turbocharged diesel engine is analysed. Based on this model, a structured approach for selecting control variables is proposed. A model-based multi-input multi-output decoupling controller is designed as the low level controller to track the desired values and to manage internal coupling. An equivalent consumption minimization strategy is employed as the supervisory level controller for real-time energy management. The supervisory level controller and low level controller work together in a cascade which addresses both fuel economy optimization and battery state-of-charge maintenance. The proposed control strategy has been successfully validated on a detailed physical simulation model.

IFAC-PapersOnLine, 2016

This paper presents that the dwell time between two consequent injection pulses of a diesel engin... more This paper presents that the dwell time between two consequent injection pulses of a diesel engine that is equipped with a common rail fuel injection system has big impact on the combustion process. It is because the change of dwell time has influence on the injection pressure for the next injection. This phenomenon was then used in implementing a Indicated Mean Effective Pressure (IMEP) closed-loop control system to reduce the cycleto-cycle combustion variations. The injected fuel quantity based IMEP closed-loop control system was also implemented and tested on the test diesel engine. Its disturbance rejection ability has been experimentally investigated to confirm that with this IMEP closed-loop control, diesel engine has strong disturbance rejection ability which implies that a speed governor with IMEP closed-loop control being the inner loop will improve engine speed control performance. Such two-loop speed control system was implemented and tested on the test engine in the lab. The inner IMEP closed-loop control for each cylinder has the same setpoint value which was calculated from the outer loop speed controller. This will increase the combustion consistency among all cylinders.

Applied Thermal Engineering, 2017

With the introduction of carbon dioxide emissions legislation for vehicles, the pressure on fuel ... more With the introduction of carbon dioxide emissions legislation for vehicles, the pressure on fuel efficiency in vehicle propulsion systems has grown significantly. Cost-effective efficiency improvements have become the topic of intensive research efforts. Amongst such efficiency measures, waste heat recovery (WHR) has attracted a deep interest both in the industrial and academic sectors. As a potentially low maintenance solid-state implementation, the thermo-electric generator (TEG) represents a promising candidate technology. Thermoelectric (TE) solutions, compared with other WHR methods have an appealing simplicity that could translate rapidly into robust engineering solutions. Achieving competitive efficiencies and low manufacturing cost however remains a substantial research challenge. Critical to progress are modelling processes that allow solutions to be formulated and assessed. The work reported in this paper demonstrates that a modelling process that makes use of mainstream computational fluid dynamics (CFD) codes is feasible. A benchmark TEG design first simulated and then run on an engine test bed showed agreement between simulation and experiment to within 10%. Closed form results for the optimised performance of module and overall TEG design have been reported in the literature and lend important insights into implementation methods. However practical implementation must take account of varying conditions and spatial variations in the heat exchange process. A CFD code that would permit a detailed evaluation TEG parameters and material properties has been demonstrated with a plate fin design of heat exchanger. Meanwhile a simpler model has achieved agreement to within 12% with the CFD code indicating that a rapid modelling process is feasible and could support new "in the loop" test techniques.

SAE Technical Paper Series, 2017

Thermoelectric generator (TEG) has received more and more attention in its application in the har... more Thermoelectric generator (TEG) has received more and more attention in its application in the harvesting of waste thermal energy in automotive engines. Even though the commercial Bismuth Telluride thermoelectric material only have 5% efficiency and 250°C hot side temperature limit, it is possible to generate peak 1kW electrical energy from a heavy-duty engine. If being equipped with 500W TEG, a passenger car has potential to save more than 2% fuel consumption and hence CO2 emission reduction. TEG has advantages of compact and motionless parts over other thermal harvest technologies such as Organic Rankine Cycle (ORC) and Turbo-Compound (TC). Intense research works are being carried on improving the thermal efficiency of the thermoelectric materials and increasing the hot side temperature limit. Future thermoelectric modules are expected to have 10% to 20% efficiency and over 500°C hot side temperature limit. This paper presents the experimental synthesis procedure of both p-type and n-type skutterudite thermoelectric materials and the fabrication procedure of the thermoelectric modules using this material. These skutterudite materials were manufactured in the chemical lab in the University of Reading and then was fabricated into modules in the lab in Cardiff University. These thermoelectric materials can work up to as high as 500°C temperature and the corresponding modules can work at maximum 400°C hot side temperature. The performance loss from materials to modules has been investigated and discussed in this paper. By using a validated TEG model, the performance improvement using these modules has been estimated compared to commercial Bisemous Telluride modules.