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  • 101.
    Leufvén, Oskar
    et al.
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Eriksson, Lars
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Measurement, analysis and modeling of compressor flow for low pressure ratios2016In: International journal of engine research, ISSN 1468-0874, Vol. 17, no 2, p. 153-168Article in journal (Other academic)
    Abstract [en]

    Increasingly stringent emissions legislation combined with consumer performance demands, have driven the development of downsized engines with complex turbocharger arrangements. To handle the complexity model-based methods have become a standard tool, and these methods need models that are capable of describing all operating modes of the systems. The models should also be easily parametrized and enable extrapolation. Both single and multiple stage turbo systems can operate with a pressure drop over their compressors, both stationary and transient. The focus here is to develop models that can describe centrifugal compressors that operate both in normal region and restriction region from standstill to maximum speed. The modeling results rely on an analysis of 305 automotive compressor maps, whereof five contain measured restriction operation, and two contain measured standstill characteristic. A standstill compressor is shown to choke at a pressure ratio of approximately 0.5, and the corresponding choking corrected mass flow being approximately 50% of the compressor maximum flow capacity. Both choking pressure ratio and flow are then shown to increase with corrected speed, and the choking pressure ratio is shown to occur at pressure ratios larger than unity for higher speeds. Simple empirical models are proposed and shown to be able to describe high flow and pressure ratios down to choking conditions well. A novel compressor flow model is proposed and validated to capture the high flow asymptote well, for speeds from standstill up to maximum.

  • 102.
    Leufvén, Oskar
    et al.
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Eriksson, Lars
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Parametrization and Validation of a Novel Surge Capable Compressor Model for MVEM using Experimental DataManuscript (preprint) (Other academic)
    Abstract [en]

    A compressor model is developed. It is capable of representing mass flow and pressure characteristic for three different regions: surge, normal operation as well as for when the compressor acts as a restriction, i.e. having a pressure ratio of less than unity. Different submodels are discussed and methods to parametrize the given model structure are given. Both the parameterization and validation are supported extensively by measured data. Transient data sets include measurements from engine test stands and a surge test stand. The compressor model is further validated against a data base of stationary compressor maps. The proposed model is shown to have good agreement with measured data for all regions, without the need for extensive geometric information or data.

  • 103.
    Leufvén, Oskar
    et al.
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Eriksson, Lars
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Time to Surge Concept and Surge Control for Acceleration Performance2008In: Proceedings of the 17th IFAC World Congress, 2008 / [ed] Chung, Myung Jin; Misra, Pradeep, International Federation of Automatic Control (IFAC) , 2008, p. 2063-2068Conference paper (Refereed)
    Abstract [en]

    Surge is a dangerous instability that can occur in compressors. It is avoided using a valve that reduces the compressor pressure. The control of this valve is important for the compressor safety but it also has a direct influence on the acceleration performance. Compressor surge control is investigated by first studying the surge phenomenon in detail. Experimental data from a dynamic compressor flow test bench and surge cycles measured on an engine is used to tune and validate a model capable of describing surge. A concept time to surge is introduced and a sensitivity analysis is performed to isolate the important characteristics that influence surge transients in an engine. It is pointed out that the controller clearly benefits from a feed-forward term due to the small time frames associated with the transition to surge. In the next step this knowledge is used in the design of a novel surge controller. This surge controller is then compared to two other controllers and it is shown that it avoids surge and improves the acceleration performance by delivering both higher engine torque and turbo shaft speed after a gear change.

  • 104.
    Llamas, Xavier
    et al.
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    Eriksson, Lars
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    A Model of a Marine Two-Stroke Diesel Engine with EGR for Low Load Simulation2016In: 9th EUROSIM Congress, 2016Conference paper (Refereed)
    Abstract [en]

    A mean value engine model of a two-stroke ma-rine diesel engine with EGR that is capable of simulatingduring low load operation is developed. In order to beable to perform low load simulations, a compressor modelcapable of low speed extrapolation is also investigated andparameterized for two different compressors. Moreover, aparameterization procedure to get good parameters for bothstationary and dynamic simulations is described and applied.The model is validated for two engine layouts of the same testengine but with different turbocharger units. The simulationresults show a good agreement with the different measuredsignals, including the oxygen content in the scavengingmanifold.

  • 105.
    Llamas, Xavier
    et al.
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    Eriksson, Lars
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    Control-Oriented Compressor Model with Adiabatic Efficiency Extrapolation2017In: SAE International Journal of Engines, ISSN 1946-3936, E-ISSN 1946-3944, Vol. 10, no 4Article in journal (Refereed)
    Abstract [en]

    Downsizing and turbocharging with single or multiple stages has been one of the main solutions to decrease fuel consumption and harmful exhaust emissions, while keeping a sufficient power output. An accurate and reliable control-oriented compressor model can be very helpful during the development phase, as well as for engine calibration, control design, diagnostic purposes or observer design. A complete compressor model consisting of mass flow and efficiency models is developed and motivated. The proposed model is not only able to represent accurately the normal region measured in a compressor map but also it is capable to extrapolate to low compressor speeds. Moreover, the efficiency extrapolation is studied by analyzing the known problem with heat transfer from the hot turbine side, which introduces errors in the measurements done in standard gas stands. Since the parameterization of the model is an important and necessary step in the modeling, a tailored parameterization approach is presented based on Total Least Squares. A standard compressor map is the only data required to parameterize the model. The parameterization is tested with a database of more than 230 compressor maps showing that it can deal well with different compressor sizes and characteristics. Also, general initialization values for the model parameters are provided using the complete database parameterization results. The results show that the model accuracy is good and in general achieves relative errors below one percent. A comparison of the model accuracy for compressor maps with and without heat transfer influence is carried out, showing a similar model accuracy for both cases but better when no heat transfer is present. Furthermore, it is shown that the model is capable to predict the efficiency characteristics at low speed of two compressor maps, measured with near adiabatic conditions.

  • 106.
    Llamas, Xavier
    et al.
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    Eriksson, Lars
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    Control-oriented modeling of two-stroke diesel engines with exhaust gas recirculation for marine applications2018In: Journal of Engineering for the Maritime Environment (Part M), ISSN 1475-0902, E-ISSN 2041-3084Article in journal (Refereed)
    Abstract [en]

    Large marine two-stroke diesel engines are widely used as propulsion systems for shipping worldwide and are facing stricter NOx emission limits. Exhaust gas recirculation is introduced to these engines to reduce the produced combustion NOx to the allowed levels. Since the current number of engines built with exhaust gas recirculation is low and engine testing is very expensive, a powerful alternative for developing exhaust gas recirculation controllers for such engines is to use control-oriented simulation models. Unfortunately, the same reasons that motivate the use of simulation models also hinder the capacity to obtain sufficient measurement data at different operating points for developing the models. A mean value engine model of a large two-stroke diesel with exhaust gas recirculation that can be simulated faster than real time is presented and validated. An analytic model for the cylinder pressure that captures the effects of changes in the fuel control inputs is also developed and validated with cylinder pressure measurements. A parameterization procedure that deals with the low number of measurement data available is proposed. After the parameterization, the model is shown to capture the stationary operation of the real engine well. The transient prediction capability of the model is also considered satisfactory which is important if the model is to be used for exhaust gas recirculation controller development during transients. Furthermore, the experience gathered while developing the model about essential signals to be measured is summarized, which can be very helpful for future applications of the model. Finally, models for the ship propeller and resistance are also investigated, showing good agreement with the measured ship sailing signals during maneuvers. These models give a complete vessel model and make it possible to simulate various maneuvering scenarios, giving different loading profiles that can be used to investigate the performance of exhaust gas recirculation and other controllers during transients.

  • 107.
    Llamas, Xavier
    et al.
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    Eriksson, Lars
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    LiU CPgui: A Toolbox for Parameterizing Compressor Models2018Report (Other academic)
    Abstract [en]

    A toolbox for parameterizing the ellipse model, that is a control-oriented compressor model, to any given measured compressor map is described in detail in this document. The compressor model has been developed in previous publications and shown to be capable of accurately reproducing the measured data obtained from gas stand measurements, for a wide range of compressors, starting from small automotive applications to large compressors used in marine propulsion. In addition, it has been shown that it is possible to extrapolate both mass flow and efficiency to the unmeasured low speed region of the compressor in a physical way. The parameterization algorithm is based on Total Least Squares (TLS), which is shown here and in previous publications to be a fast and reliable approach to fit the compressor model to the map. The toolbox is implemented in a Matlab Graphical User Interface (GUI) in order to make it easy for the user to parameterize the compressor model. To demonstrate the workflow and ease of use, a complete step-by-step example of how to work with the toolbox is provided. To further facilitate the user in applying the model, the package also provides implementations of the ellipse compressor model both as a Matlab function and as a Simulink block. This way, the user can quickly and reliably use the results of the parameterization process in a desired application, e.g. including the compressor model of a given compressor map in a combustion engine simulation model.

  • 108.
    Llamas, Xavier
    et al.
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    Eriksson, Lars
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    Optimal Transient Control of a Heavy DutyDiesel Engine with EGR and VGT2014In: Proceedings of the 19th IFAC World Congress / [ed] Boje, Edward, Xia, Xiaohua, Cape Town, South Africa: IFAC Papers Online, 2014, Vol. 19, p. 11854-11859Conference paper (Refereed)
    Abstract [en]

    Optimal control of a heavy duty diesel engine with EGR and VGT during transients is investigated. Minimum time and fuel optimal control problems are defined for transients from low to high output torque. A validated diesel engine model is used with minor changes in order to be suitable for the selected solver. The problem is solved for several feasible minimum EGR fractions and smoke-limiter values in order to provide comparisons. The optimization results show that the smoke-limiter has great effect on the transient duration while the required EGR fraction influences the control signals' shape. The fuel optimal control keeps the control actuators more closed than the time optimal, however both time and fuel optimal results become very similar when high EGR fractions and smoke-limiter values are required.

  • 109.
    Llamas, Xavier
    et al.
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    Eriksson, Lars
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    Parameterizing Compact and Extensible Compressor Models Using Orthogonal Distance Minimization2016In: Journal of engineering for gas turbines and power, ISSN 0742-4795, E-ISSN 1528-8919, Vol. 139, no 1, p. 012601-1-012601-10, article id GTP-15-1569Article in journal (Refereed)
    Abstract [en]

    A complete and compact control-oriented compressor model consisting of a mass flow submodel and an efficiency submodel is described. The final application of the model is a complete two-stroke mean value engine model (MVEM) which requires simulating the compressor operating at the low-flow and low-pressure ratio area. The model is based on previous research done for automotive-size compressors, and it is shown to be general enough to adapt well to the characteristics of the marine-size compressors. A physics-based efficiency model allows, together with the mass flow model, extrapolating to low-pressure ratios. The complexity of the model makes its parameterization a difficult task; hence, a method to efficiently estimate the 19 model parameters is proposed. The method computes analytic model gradients and uses them to minimize the orthogonal distances between the modeled speed lines (SpLs) and the measured points. The results of the parameter estimation are tested against nine different standard marine-size maps showing good agreement with the measured data. Furthermore, the results also show the importance of estimating the parameters of the mass flow and efficiency submodels at the same time to obtain an accurate model. The extrapolation capabilities to low-load regions are also tested using low-load measurements from an automotive-size compressor. It is shown that the model follows the measured efficiency trend down to low loads.

  • 110.
    Llamas, Xavier
    et al.
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Eriksson, Lars
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Sundström, Christofer
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Fuel Efficient Speed Profiles for Finite Time Gear Shift with Multi-Phase Optimization2013In: 54th SIMS Conference on Simulation and Modelling, SIMS 2013, 2013Conference paper (Refereed)
    Abstract [en]

    A method that finds fuel optimal speed profiles for traveling a predefined distance is presented. The vehicle is modeled using a quasistatic formulation and an optimal control problem is defined. In addition, the solving method is based on a multi-phase optimization algorithm based on dynamic programming. This approach results in lower computational time than solving the problem directly with dynamic programming, it also makes the computational time independent of the travel distance. In addition, the simulation generated data can be used to get the solution to several optimal control problems in parallel that have additional constraints. Further a finite time gear shift model is presented to include the gear selection in the optimization problem. The problem also considers speed losses and fuel consumption during the maneuver. The results presented show the optimal speed and gear profiles to cover a distance, making special emphasis at the acceleration phase, where it is optimal to perform a fast acceleration to engage the highest gear as soon as possible. Finally a proposed application is to use the simulation data to provide eco-driving tips to the driver.

  • 111.
    Myklebust, Andreas
    et al.
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Eriksson, Lars
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Modeling, Observability, and Estimation of Thermal Effects and Aging on Transmitted Torque in a Heavy Duty Truck with a Dry Clutch2015In: IEEE/ASME transactions on mechatronics, ISSN 1083-4435, E-ISSN 1941-014X, Vol. 20, no 1, p. 61-72Article in journal (Refereed)
    Abstract [en]

    A transmission with both high comfort and high efficiency is the Automated Manual Transmission (AMT). To be able to control and fully utilize this type of transmission it is of great importance to have knowledge about the torque transmissibility curve of the clutch. The transmitted torque in a slipping dry clutch is therefore studied in experiments with a heavy duty truck (HDT). It is shown that the torque characteristic has little or no dependence on slip speed, but that there are two dynamic effects that make the torque vary up to 900 Nm for the same clutch actuator position. Material expansion with temperature can explain both phenomena and a dynamic clutch temperature model that can describe the dynamic torque variations is developed. The dynamic model is validated in experiments, and it is shown to reduce the error in transmitted torque from 7 % to 3 % of the maximum engine torque compared to a static model. Clutch wear is also a dynamic phenomenon that is of interest to track and compensate for, and therefore the model is augmented with an extra state describing wear. An observability analysis is performed showing that the augmented model is fully or partially observable depending on the mode of operation. In particular, by measuring the actuator position the temperature states are observable, both during slipping of the clutch and when it is fully closed. An Extended Kalman Filter (EKF), which observes the temperature states, was developed since it is straight forward to incorporate different modes of operation. The EKF was evaluated on measurement data and the estimated states converged from poor initial values, enabling prediction of the translation of the torque transmissibility curve. The computional complexity of the EKF is low and thus it is suitable for real-time applications. Modeling, parameter estimation, observer design and validation are all carried out using production sensors only and therefore it is straight forward to implement the observer in a production HDT following the presented methodology.

  • 112.
    Myklebust, Andreas
    et al.
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Eriksson, Lars
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Road Slope Analysis and Filtering for Driveline Shuffle Simulation2012Conference paper (Refereed)
    Abstract [en]

    In powertrain analysis, simulation of driveline models are standard tools, where efficient and accurate simulations are important features of the models. One input signal with high impact on the accuracy is the road slope. Here it is found that the amplitude discretization in production road-slope sensors can excite vehicle shuffle dynamics in the model, which is not present in the real vehicle. To overcome this problem road-slope information is analyzed with the aid of both measured and synthetic road profiles, where the latter are generated from regulatory road specifications. The analysis shows that it is possible to separate vehicle shuffle resonances and road-slope information, and designs are proposed for on- and off-line filtering of the road-slope-sensor signal in spatial coordinates. Applying the filter to measured data shows that vehicle shuffle is significantly attenuated, while the shape of the road slope profile is maintained. As a byproduct the use of smoothing the rolling resistance is shown.

  • 113.
    Myklebust, Andreas
    et al.
    Linköping University, Department of Electrical Engineering, Vehicular Systems.
    Eriksson, Lars
    Linköping University, Department of Electrical Engineering, Vehicular Systems.
    The Effect of Thermal Expansion in a Dry Clutch on Launch Control2013In: AAC’13 – 7th IFAC Symposium on Advances in Automotive Control, 2013Conference paper (Refereed)
    Abstract [en]

    A dry clutch model with thermal dynamics is added to a driveline model of a heavyduty truck equipped with an automated manual transmission. The model captures driveline oscillations and can be used to simulate how different clutch-control strategies affect vehicle performance, drivability and comfort. Parameters are estimated to fit a heavy-duty truck and the complete model is validated with respect to shuffle, speed trajectory, clutch torque and clutch lock-up/break-apart behavior. The model shows good agreement with data. Furthermore the model is used to study the effect of thermal expansion in the clutch on launch control. It is shown that the effect of thermal expansion, even for moderate temperatures, is significant in launch control applications.

  • 114.
    Myklebust, Andreas
    et al.
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Eriksson, Lars
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    The Effect of Thermal Expansion in a Dry Clutch on Launch Control: Advances in Automotive Control, Volume # 7, Part # 12013Conference paper (Refereed)
    Abstract [en]

    A dry clutch model with thermal dynamics is added to a driveline model of a heavy-duty truck equipped with an automated manual transmission. The model captures driveline oscillations and can be used to simulate how different clutch-control strategies affect vehicle performance, drivability and comfort. Parameters are estimated to fit a heavy-duty truck and the complete model is validated with respect to shuffle, speed trajectory, clutch torque and clutch lock-up/break-apart behavior. The model shows good agreement with data. Furthermore the model is used to study the effect of thermal expansion in the clutch on launch control. It is shown that the effect of thermal expansion, even for moderate temperatures, is significant in launch control applications.

  • 115.
    Myklebust, Andreas
    et al.
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Eriksson, Lars
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Torque Model with Fast and Slow Temperature Dynamics of a Slipping Dry Clutch2012In: 2012 IEEE VEHICLE POWER AND PROPULSION CONFERENCE (VPPC), IEEE , 2012, p. 851-856Conference paper (Refereed)
    Abstract [en]

    The transmitted torque in a slipping dry clutch is studied in experiments with a heavy duty truck. It is shown that the torque characteristic has little or no dependence on slip speed, but that there are two dynamic effects that make the torque vary up to 900 Nm for the same clutch actuator position. Material expansion with temperature can explain both phenomena and a dynamic clutch temperature model with two different time constants is developed. The dynamic model is validated in experiments, with an error of only 3% of the maximum engine torque, and is shown to improve the behavior significantly compared to a static model.

  • 116.
    Nezhadali, Vaheed
    et al.
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    Eriksson, Lars
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    A framework for modeling and optimal control of automatic transmission systems2015In: 4th IFAC Workshop on Engine and Powertrain Control, Simulation and Modeling (E-COSM 2015): Proceedings of a meeting held 23-26 August 2015, Columbus, Ohio, USA / [ed] Simona Onori, Elsevier, 2015, Vol. 48 Issue 15, no 15, p. 285-291Conference paper (Refereed)
    Abstract [en]

    Abstract Development of efficient control algorithms for the control of automatic transmission systems is crucial to maintain passenger comfort and operational life of the transmission components. An optimization framework is developed by state space modeling of a powertrain including a nine speed automatic transmission, diesel engine, torque converter and a model for longitudinal vehicle dynamics considering drive shaft as the only flexibility of the driveline. Emphasis is set on the kinematics of the automatic transmission with the aim of modeling for gearshift optimal control during the inertia phase. Considering the interacting forces between planetary gearsets, clutches and brakes in the transmission, kinematic equations of motion are derived for rotating transmission components enabling to calculate both transmission dynamics and internal forces. The model is then used in optimal control problem formulations for the analysis of optimal control transients in two up-shift cases.

  • 117.
    Nezhadali, Vaheed
    et al.
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    Eriksson, Lars
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    Analysis of optimal diesel-electric powertrain transients during a tip-in maneuver2016Conference paper (Refereed)
    Abstract [en]

    Optimal transients of a hybrid powertrain are calculated with the aim to give a smooth and time efficient acceleration. It is shown that there is a trade-off between time and driveline oscillations where high oscillations can be avoided by slightly longer acceleration time and proper control of the electrical and diesel power sources. During a low oscillation acceleration, there is still the possibility to reduce the amount of total consumed electrical and fuel energy. This is investigated by calculation of optimal controls during acceleration for a fixed time while penalizing the usage of energy in a low oscillation acceleration. The balance between electrical and diesel energy usage during the acceleration is also investigated. The results show that to avoid extreme transients by optimal control, a multidimensional formulation of the objective function including different properties should be considered.

  • 118.
    Nezhadali, Vaheed
    et al.
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Eriksson, Lars
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Optimal control of a diesel-electric powertrain during an up-shift2016Conference paper (Refereed)
    Abstract [en]

    To investigate the optimal controls of a diesel-electric powertrain during a torque controlled gearshift, a powertrain model is developed. A validated diesel-electric model is used as the power source and the transmission dynamics are described by different sets of differential equations during torque phase, synchronization phase and inertia phase of the gearshift. Using the developed model, multi-phase optimal control problems are formulated and solved. The trade-off between gearshift duration and driveline oscillations are calculated and efficient gearshift transients for a diesel-electric and pure diesel powertrain are then compared and analyzed.

  • 119.
    Nezhadali, Vaheed
    et al.
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    Eriksson, Lars
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    Optimal control of engine controlled gearshift for a diesel-electric powertrain with backlash2016In: IFAC PAPERSONLINE, IFAC , 2016, Vol. 49, p. 762-768Conference paper (Refereed)
    Abstract [en]

    Gearshift optimal control of a hybrid powertrain with a lumped/decoupled transmission model and backlash dynamics in the driveline is studied. A model is used for a heavy duty powertrain including a validated mean value diesel engine model with electric generator, transmission dynamics representing the dynamics of the automated manual transmission system and driveshaft flexibilities. Backlash dynamics are also included in the driveline model by introducing a switching function. By applying numerical optimal control methods and dividing the gearshift process into separate phases, optimization problems are solved to investigate the minimum time and low Jerk gearshift transients. The controls are also calculated with fuel penalties added to the minimum Jerk optimization and the transients are analyzed.

  • 120.
    Nezhadali, Vaheed
    et al.
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Eriksson, Lars
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Optimal control of wheel loader operation in the short loading cycle using two braking alternatives2013Conference paper (Refereed)
    Abstract [en]

    The optimal control of wheel loader operation is used in order to investigate the potentials for fuel cost and cycle time minimization during the short loading cycle. The wheel loader is modeled as a nonlinear system with three control inputs and four state variables where a diesel engine generates the power utilized for lifting and traction. The lifting system is modeled considering the limitations in the hydraulics and also the structural constraints. A torque converter is included in the driveline model which introduces nonlinearities into the system and operates in different modes affecting the fuel consumption. The gear shifts during the loading cycle impose a discrete variable into the system and this is taken care of by representing the loading cycle as a multi-phase optimal control problem with constant gearbox gear ratio in each phase. Minimum fuel and minimum time system transients are calculated and analyzed for two alternative cases one where the torque converter is used to stop the vehicle before reaching the reversing point and another where the service brakes are utilized. The optimal control problem is iteratively solved in order to obtain the trade-off between fuel consumption and cycle time for both braking alternatives. It is shown that although the engine operates at lower speeds when the torque converter is used for braking, the fuel consumption increases as higher torques are demanded from the engine during braking. The increase in fuel consumption is higher in faster cycle operations as the vehicle travels at higher speeds and larger torques are required to stop the vehicle. Wheel loader operators tend to use torque converter braking alternative as it is more convenient; however, it accompanies higher fuel consumption which highlights the importance of developing intelligent and easy to use braking systems.

  • 121.
    Nezhadali, Vaheed
    et al.
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    Eriksson, Lars
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    Optimal lifting and path profiles for a wheel loader considering engine and turbo limitations2014In: Optimization and optimal control in automotive systems / [ed] Harald Waschl, Ilya Kolmanovsky, Maarten Steinbuch and Luigi del Re, Cham: Springer, 2014, p. 301-324Chapter in book (Refereed)
    Abstract [en]

    Time and fuel optimal control of an articulated wheel loader is studied during the lift and transport sections of the short loading cycle. A wheel loader model is developed including engine (with turbo dynamics), torque converter, transmission and vehicle kinematics, lifting hydraulics and articulated steering. The modeling is performed with the aim to use the models for formulating and solving optimal control problems. The considered problem is the lift and transport section of the wheel loader that operates in the short loading cycle, with several different load receiver positions, while the considered criteria are minimum time and minimum fuel. The problem is separated into four phases to avoid solving a mixed integer problem imposed by the gearshifting discontinuities. Furthermore, two different load lifting patterns are studied one with the lifting free and one with the lifting performed only in the last 30 % of the transport. The results show that the optimal paths to the load receiver are identical for both minimum time and minimum fuel cycles and do not change when the loading lifting pattern is altered. A power break-down during the wheel loader operation is presented for the selected cycles of normal and delayed lifting where it is shown that the cycle time remains almost unchanged when lifting is delayed while the fuel consumption slightly decreases in minimum time transients.

  • 122.
    Nezhadali, Vaheed
    et al.
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    Eriksson, Lars
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    Wheel loader optimal transients in the short loading cycle2014In: Proceedings of the 19th IFAC World Congress, 2014 / [ed] Edward Boje and Xiaohua Xia, Elsevier, 2014, Vol. 47, no 3, p. 7917-7922Conference paper (Refereed)
    Abstract [en]

    Abstract A nonlinear wheel loader model with nine states and four control inputs is utilized to study the fuel and time efficient optimal control of wheel loader operation in the short loading cycle. The wheel loader model consists of lifting, steering and powertrain subsystems where the nonlinearity originates from the torque converter in the drivetrain. The short loading cycle, from loading point to a load receiver and back to the loading point, for a fork lifting application is described in terms of boundary conditions of the optimization problem while the operation is divided into several phases with constant gearbox gear ratios in order to avoid discontinuities due to discrete gear ratios. The effect of load receiver standing orientation on the wheel loader trajectory, fuel consumption and cycle time is studied showing that a small deviation from the optimal orientation (≈ 20 [deg]) results in up to 18 % higher fuel consumption in the minimum time cycles. Also, an alternative lifting strategy where for operation safety load is lifted only when wheel loaders moves forward is studied showing that this increases the fuel consumption of a typical 25 [sec] cycle only less than 2 %. The wheel loader path between loading point and load receiver is also calculated by optimization and analyzed for different cases. It is shown that when the load receiver orientation is not optimized and is set manually, the time or fuel optimal paths will differ from the shortest distance path, however when the load receiver orientation is calculated by optimization the fuel, time and shortest distance paths become identical.

  • 123.
    Nezhadali, Vaheed
    et al.
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    Eriksson, Lars
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    Fröberg, Anders
    Volvo Construction Equipment, Eskiltuna, Sweden.
    Modeling and optimal control of a wheel loader in the lift-transport section of the short loading cycle2013In: Elsevier IFAC Publications / IFAC Proceedings series, ISSN 1474-6670, Vol. 46, no 21, p. 195-200Article in journal (Refereed)
    Abstract [en]

    Abstract Optimal control of a wheel loader operating in the short loading cycle is studied in order to investigate the potentials for fuel consumption reduction while maintaining acceptable production rates. The wheel loader is modeled as a system with five states and three control inputs including torque converter nonlinearities. The torque converter is modeled with no lockup enabling power transmission in both directions. The geometry of the wheel loader boom and the demanded force in the lift cylinders during lifting are used to ensure that the in-cylinder pressure remains below component’s limits. The lift-transport section of the short loading cycle is divided into four phases due to discontinuities in the gearbox ratios and fuel consumption is calculated in each phase. Time optimal and fuel optimal transients of the system and the power consumption in each and every component is presented showing the dominance of the torque converter losses compared to the other components especially in the time optimal solutions. It is shown that introducing path constraints on the maximum lifting speed of the bucket due to limitations in hydraulic pumping speed moves the diesel engine operation towards higher speeds in order to maintain the lifting speed. Trade-off between fuel optimal and time optimal transients is calculated which is found to be in agreement with the results of experimental studies.

  • 124.
    Nezhadali, Vaheed
    et al.
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    Frank, B.
    Lund University, Sweden.
    Eriksson, Lars
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    Wheel loader operation-Optimal control compared to real drive experience2016In: Control Engineering Practice, ISSN 0967-0661, E-ISSN 1873-6939, Vol. 48, p. 1-9Article in journal (Refereed)
    Abstract [en]

    Wheel loader trajectories between loading and unloading positions in a repetitive loading cycle are studied. A wheel loader model available in the literature is improved for better fuel estimation and optimal control problems are formulated and solved using it. The optimization results are analyzed in a side to side comparison with measurement data from a real world application. It is shown that the trajectory properties affect the operation productivity. However, efficient trajectories are not the only requirement for high productivity operation and all major power consuming sources such as vehicle dynamics, lifting and steering have to be included in the optimization for productivity analysis. The effect of operator steering capability is also analyzed showing that development of autonomous vehicles can be envisaged especially for repetitive cycles. (C) 2015 Elsevier Ltd. All rights reserved.

  • 125.
    Nezhadali, Vaheed
    et al.
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Sivertsson, Martin
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Eriksson, Lars
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Turbocharger Dynamics Influence on Optimal Control of Diesel Engine Powered Systems2014In: SAE International Journal of Engines, ISSN 1946-3936, Vol. 7, no 1, p. 6-13Article in journal (Refereed)
    Abstract [en]

    The importance of including turbocharger dynamics in diesel engine models are studied, especially when optimization techniques are to be used to derive the optimal controls. This is done for two applications of diesel engines where in the first application, a diesel engine in wheel loader powertrain interacts with other subsystems to perform a loading operation and engine speed is dictated by the wheel speed, while in the second application, the engine operates in a diesel-electric powertrain as a separate system and the engine speed remains a free variable. In both applications, mean value engine models of different complexities are used while the rest of system components are modeled with the aim of control study. Optimal control problems are formulated, solved, and results are analyzed for various engine loading scenarios in the two applications with and without turbocharger dynamics. It is shown that depending on the engine loading transients, fuel consumption and operation time can widely vary when the turbocharger dynamics are considered in the diesel engine model. Including these, have minor effects on fuel consumption and operation time at minimum fuel operations of the first application (~0.1 %) while the changes are considerable in the second application (up to 60%). In case of minimum time operations however, fuel consumption and operation time are highly affected in both applications implying that not considering turbocharger dynamics in the diesel engine models may lead to overestimation of the engine performance especially when the results are going to be used for control purposes.

  • 126.
    Nickmehr, Neda
    et al.
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Eriksson, Lars
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Åslund, Jan
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Methodology for modeling, parameter estimation and validation of powertrain torsional vibration2013In: The 54th SIMS conference on Simulation and Modelling, 2013Conference paper (Refereed)
    Abstract [en]

    A vehicular powertrain is a lightly damped dynamic system that transfers the engine torque to the driving wheels through a number of inertias and elastic elements. Therefore, it is prone to vibrate and emit noise when disturbances are applied. Providing a methodology, for powertrain vibration modeling and simulation, is one of the key steps in various research topics in the field of automobile engineering. Verification of the engine crankshaft torsion and vibration model, as a subsystem of the powertrain, is proposed in this paper. This is achieved by constructing a rotational multi-body system in MATLAB and utilizing nonlinear least squares method for estimation of the model parameters. The simulated engine angular velocity is compared to the measured data, from a car, which shows a good agreement.

  • 127.
    Nielsen, Kraen Vodder
    et al.
    MAN Diesel and Turbo, Denmark; Tech Univ Denmark, Denmark.
    Blanke, Mogens
    Tech Univ Denmark, Denmark; Norwegian Univ Sci and Technol, Norway.
    Eriksson, Lars
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    Adaptive Observer for Nonlinearly Parameterized Hammerstein System With Sensor Delay-Applied to Ship Emissions Reduction2018In: IEEE Transactions on Control Systems Technology, ISSN 1063-6536, E-ISSN 1558-0865, Vol. 26, no 4, p. 1508-1515Article in journal (Refereed)
    Abstract [en]

    Taking offspring in a problem of ship emission reduction by exhaust gas recirculation control for large diesel engines, an underlying generic estimation challenge is formulated as a problem of joint state and parameter estimation for a class of multiple-input single-output Hammerstein systems with first-order dynamics, sensor delay, and a bounded time-varying parameter in the nonlinear part. This brief suggests a novel scheme for this estimation problem that guarantees exponential convergence to an interval that depends on the sensitivity of the system. The system is allowed to be nonlinear, parameterized, and time dependent, which are characteristics of the industrial problem we study. The approach requires the input nonlinearity to be a sector nonlinearity in the time-varying parameter. Salient features of the approach include simplicity of design and implementation. The efficacy of the adaptive observer is shown on simulated cases, on tests with a large diesel engine on test bed, and on tests with a container vessel.

  • 128.
    Nielsen, Kraen Vodder
    et al.
    MAN Diesel and Turbo, Denmark; Tech Univ Denmark, Denmark.
    Blanke, Mogens
    Tech Univ Denmark, Denmark; Norwegian Univ Sci and Technol, Norway.
    Eriksson, Lars
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    Vejlgaard-Laursen, Morten
    MAN Diesel and Turbo, Denmark.
    Marine diesel engine control to meet emission requirements and maintain maneuverability2018In: Control Engineering Practice, ISSN 0967-0661, E-ISSN 1873-6939, Vol. 76, p. 12-21Article in journal (Refereed)
    Abstract [en]

    International shipping has been reported to account for 13% of global NOx emissions and 2.1% of global green house gas emissions. Recent restrictions of NOx emissions from marine vessels have led to the development of exhaust gas recirculation (EGR) for large two-stroke diesel engines. Meanwhile, the same engines have been downsized and derated to optimize fuel efficiency. The smaller engines reduce the possible vessel acceleration, and to counteract this, the engine controller must be improved to fully utilize the physical potential of the engine. A fuel index limiter based on air/fuel ratio was recently developed (Turbo, 2016), but as it does not account for EGR, accelerations lead to excessive exhaust smoke formation which could damage the engine when recirculated. This paper presents two methods for extending a fuel index limiter function to EGR engines. The methods are validated through simulations with a mean-value engine model and on a vessel operating at sea. Validation tests compare combinations of the two index limiter methods, using either traditional PI control for the EGR loop or the recently developed fast adaptive feedforward EGR control (Nielsen et al., 2017a). The experiments show that the extended limiters reduce exhaust smoke formation during acceleration to a minimum, and that the suggested limiter, combined with adaptive feedforward EGR control, is able to maintain full engine acceleration capability. Sea tests with engine speed steps from 35 to 50 RPM, made peak exhaust opacity increase by only 5% points when using the proposed limiter, whereas it increased 70% points without the limiter.

  • 129.
    Nielsen, Lars
    et al.
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    Eriksson, Lars
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    An Ion-Sense Engine-Fine-Tuner1998In: IEEE Control Systems, ISSN 1066-033X, Vol. 18, no 5, p. 43-52Article in journal (Refereed)
    Abstract [en]

    IEEE Control Systems: Special Issue on Powertrain Control, October 1998 Combustion engines are highly engineered complex system. Many variables like engine speed and load are measured, but there are many other variables influencing engine performance that are not measured. One such variable that strongly influences efficiency and power is air humidity. Even with such varying unmeasured variables, it is well known that a skilled human mechanic can diagnose and fine tune a car according to the environment and circumstances at a certain place and day. Inspired by these skills in combination with the development of computing power, it is possible to think of virtual engine-doctors and virtual engine-fine-tuners. Here an ion-sense engine-fine-tuner has been developed based on spark advance feed-back control using ionization current interpretation. It is shown, as a main result, that it can control the engine back to its optimal operation even when subjected to humidity in the intake air.

  • 130.
    Nilsson, Ylva
    et al.
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    Eriksson, Lars
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    A New Formulation of Multi-Zone Combustion Engine Models2001In: Advances in Automotive Control 2001, Pergamon Press, 2001, p. 629-634Conference paper (Refereed)
    Abstract [en]

    Cylinder pressure simulation has grown to become an important tool when developing and evaluating new engine concepts and control strategies. A new formulation of zero-dimensional multi-zone models is developed and described. A general model structure is formulated that rely on a set of differential algebraic equations that are easy to solve. The selected formulation also results in models that are easy to scale, i.e. add new zones, and to increase complexity, which is a result of the selected structure. A number of important issues that can cause problems when simulating the model are treated. It is shown: a) How a new zone is initialized. b) How variables of varying magnitude can be scaled to avoid numerical difficulties. c) How numerical errors accumulated during the simulation can be reduced by using a set of consistency equations.

  • 131.
    Nilsson, Ylva
    et al.
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    Eriksson, Lars
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    Determining TDC Position using Symmetry and other Methods2004In: Modeling of Spark Ignition Engines, SAE , 2004Conference paper (Refereed)
    Abstract [en]

    It is important to determine the phasing of a measured cylinder pressure trace and crank angle with high accuracy. The reason is that erroneous determination of the position of TDC is a major error source when calculating properties such as heat release etc. A common way to determine the TDC position is to study motored cycles. Heat transfer makes the task more complicated, since it shifts the position of the maximum pressure away from TDC.

    In this paper a new method for determining the TDC position is proposed that does not require any additional sensors other than a cylinder pressure sensor and an incremental encoder. The idea is to find a point that the cylinder pressure from a motored cycle is symmetric around, since the volume is close to symmetric on either side of TDC. The new method and four published methods are tested and evaluated. Cylinder pressure data used for comparison are from simulations of a SAAB Variable Compression engine. The investigation shows that the methods have an error that is in the range of 0.1 crank angles or less, but are sensitive to errors in geometry and heat transfer information. The symmetry method is less sensitive to these errors than most of the other methods, and is not affected by an offset or gain error in the cylinder pressure signal. It is also the least sensitive method with respect to noise.

  • 132.
    Nilsson, Ylva
    et al.
    Linköping University, Department of Electrical Engineering.
    Eriksson, Lars
    Linköping University, Department of Electrical Engineering.
    Determining TDC using Symmetry and other Methods2004Conference paper (Refereed)
  • 133.
    Nilsson, Ylva
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Electrical Engineering, Vehicular Systems.
    Eriksson, Lars
    Linköping University, The Institute of Technology. Linköping University, Department of Electrical Engineering, Vehicular Systems.
    Gunnarsson, Martin
    Linköping University, The Institute of Technology. Linköping University, Department of Electrical Engineering, Vehicular Systems.
    A Model for Fuel Optimal Control of a Spark-Ignited Variable Compression Engine2006Conference paper (Refereed)
  • 134.
    Nilsson, Ylva
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Electrical Engineering, Vehicular Systems.
    Eriksson, Lars
    Linköping University, The Institute of Technology. Linköping University, Department of Electrical Engineering, Vehicular Systems.
    Gunnarsson, Martin
    Linköping University, The Institute of Technology. Linköping University, Department of Electrical Engineering, Vehicular Systems.
    Modeling for Fuel Optimal Control of SI VCR Engines2006Conference paper (Refereed)
  • 135.
    Nilsson, Ylva
    et al.
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    Eriksson, Lars
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    Gunnarsson, Martin
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    Modelling for Fuel Optimal Control of SI VCR Engines2006In: Proceedings of New Trends in Engine Control, Simulation and Modelling, Institut Francais du Petrole , 2006Conference paper (Refereed)
  • 136.
    Nilsson, Ylva
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Electrical Engineering.
    Eriksson, Lars
    Linköping University, The Institute of Technology. Linköping University, Department of Electrical Engineering, Vehicular Systems.
    Gunnarsson, Martin
    Linköping University, The Institute of Technology. Linköping University, Department of Electrical Engineering.
    Torque modelling for optimising fuel economy in variable compression engines2008In: International Journal of Modelling, Identification and Control, ISSN 1746-6172, Vol. 3, no 3, p. 327-339Article in journal (Refereed)
    Abstract [en]

    Fuel optimal control of a variable compression engine is studied and it is shown that a crucial component is the model for the engine torque. A model for the produced work that captures the important effects of ignition and compression ratio is proposed and investigated. The main task for the model is to be a mean for determining the fuel optimal control signals, for each requested engine torque and speed. The contribution is a model suitable for finding this optimal combination. This model consists of well-known components, and the novelty lies in the compilation and validation of the control-oriented efficiency model for a variable compression engine. The modelling and validation is performed on a multicylinder variable compression engine using two fuels with different octane rating. Despite the models simplicity, it describes the indicated work with good accuracy, and suits its purpose of finding optimal control signals. In the evaluation, it is shown that a fuel optimal controller based on the proposed model captures the optimal IMEP to within 1.2%. This corresponds to a loss in engine efficiency that is in the range of 0.5% units or less. Copyright © 2008, Inderscience Publishers.

  • 137.
    Sciarretta, A.
    et al.
    IFP Energies Nouvelles, France .
    Serrao, L.
    Dana Corporation, Italy.
    Dewangan, P.C.
    IFP Energies Nouvelles, France; IFP School, France .
    Tona, P.
    IFP Energies Nouvelles, France .
    Bergshoeff, E.N. D.
    TU Eindhoven, Netherlands.
    Bordons, C.
    University of Seville, Spain .
    Charmpa, L.
    IFP Sch, France Continental, France .
    Elbert, Ph.
    ETH Zurich, Switzerland.
    Eriksson, Lars
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Hofman, T.
    TU Eindhoven, Netherlands .
    Hubacher, M.
    TU Eindhoven, Netherlands .
    Isenegger, R.
    TU Eindhoven, Netherlands .
    Lacandia, F.
    Ohio State University, USA.
    Laveau, A.
    IFP School, France.
    Li, H.
    IFP School, France.
    Marcos, D.
    University of Seville, Spain .
    Nueesch, T.
    ETH Zurich, Switzerland.
    Onori, S.
    Ohio State University, USA .
    Pisu, P.
    Clemson University, USA .
    Rios, J.
    Clemson University, USA .
    Silvas, E.
    TU Eindhoven, Netherlands .
    Sivertsson, Martin
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Tribioli, L.
    Ohio State University, USA .
    van der Hoeven, A.-J.
    TU Eindhoven, Netherlands .
    Wu, M.
    IFP School, France.
    A control benchmark on the energy management of a plug-in hybrid electric vehicle2014In: Control Engineering Practice, ISSN 0967-0661, E-ISSN 1873-6939, Vol. 29, p. 287-298Article in journal (Refereed)
    Abstract [en]

    A benchmark control problem was developed for a special session of the IFAC Workshop on Engine and Powertrain Control, Simulation and Modeling (E-COSM 12), held in Rueil-Malmaison, France, in October 2012. The online energy management of a plug-in hybrid-electric vehicle was to be developed by the benchmark participants. The simulator, provided by the benchmark organizers, implements a model of the GM Voltec powertrain. Each solution was evaluated according to several metrics, comprising of energy and fuel economy on two driving profiles unknown to the participants, acceleration and braking performance, computational performance. The nine solutions received are analyzed in terms of the control technique adopted (heuristic rule-based energy management vs. equivalent consumption minimization strategies, ECMS), battery discharge strategy (charge depleting-charge sustaining vs. blended mode), ECMS implementation (vector-based vs. map-based), ways to improve the implementation and improve the computational performance. The solution having achieved the best combined score is compared with a global optimal solution calculated offline using the Pontryagins minimum principle-derived optimization tool HOT.

  • 138.
    Shen, Tielong
    et al.
    Sophia Univ, Japan.
    Eriksson, Lars
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    Special focus on learning and real-time optimization of automotive powertrain systems2018In: Science China Information Sciences, ISSN 1674-733X, E-ISSN 1869-1919, Vol. 61, no 7, article id 70200Article in journal (Other academic)
    Abstract [en]

    n/a

  • 139.
    Shitahun, Alachew
    et al.
    Linköping University, Department of Computer and Information Science, PELAB - Programming Environment Laboratory. Linköping University, The Institute of Technology.
    Ruge, Vitalij
    University of Applied Sciences, Bielefeld, Germany.
    Gebremedhin, Mahder
    Linköping University, Department of Computer and Information Science, PELAB - Programming Environment Laboratory. Linköping University, The Institute of Technology.
    Bachmann, Bernhard
    University of Applied Sciences, Bielefeld, Germany.
    Eriksson, Lars
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Andersson, Joel
    Diehl, Moritz
    Engineering Center (OPTEC), Leuven, Belgium.
    Fritzson, Peter
    Linköping University, Department of Computer and Information Science, PELAB - Programming Environment Laboratory. Linköping University, The Institute of Technology.
    Model-Based Dynamic Optimization with OpenModelica and CasADi2013In: IFAC-AAC 2013, 2013, p. 446-451Conference paper (Refereed)
    Abstract [en]

    This paper demonstrates model-based dynamic optimization through the coupling of two open source tools: OpenModelica, which is a Modelica-based modeling and simulation platform, and CasADi, a framework for numerical optimization. The coupling uses a standardized XML format for exchange of differential-algebraic equations (DAE) models. OpenModelica supports export of models written in Modelica and the optimization language extension using this XML format, while CasADi supports import of models represented in this format. This allows users to define optimal control problems (OCP) using Modelica and optimization language specification, and solve the underlying model formulation using a range of optimization methods, including direct collocation and direct multiple shooting. The proposed solution has been tested on several industrially relevant optimal control problems, including a diesel-electric power train.

  • 140.
    Sivertsson, Martin
    et al.
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Eriksson, Lars
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    An Optimal Control Benchmark: Transient Optimization of a Diesel-Electric Powertrain2014In: Proceedings of the 55th International Conference on Simulation and Modelling (SIMS 55), 21-22 October, Modelling, Simulation and Optimization / [ed] Alireza Rezania Kolai, Kim Sørensen & Mads Pagh Nielsen, Linköping University Electronic Press, 2014, p. 59-63Conference paper (Refereed)
    Abstract [en]

    An optimal control benchmark is presented and discussed. The benchmark is optimal transient control of a nonlinear four state three control model of a diesel-electric powertrain and constructed in such a manner that it is available in several versions to be of interest for developers of optimal control tools at different levels of development. This includes with and without time as a parameter as well as with and without time varying constraints.

  • 141.
    Sivertsson, Martin
    et al.
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Eriksson, Lars
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Design and Evaluation of Energy Management using Map-Based ECMS for the PHEV Benchmark2014In: Oil & gas science and technology, ISSN 1294-4475, E-ISSN 1953-8189, Vol. 70, no 1, p. 195-211Article in journal (Refereed)
    Abstract [en]

    Plug-in Hybrid Electric Vehicles (PHEV) provide a promising way of achieving the benefits of the electric vehicle without being limited by the electric range, but they increase the importance of the supervisory control to fully utilize the potential of the powertrain. The winning contribution in the PHEV Benchmark organized by IFP Energies nouvelles is described and evaluated. The control is an adaptive strategy based on a map-based Equivalent Consumption Minimization Strategy (ECMS) approach, developed and implemented in the simulator provided for the PHEV Benchmark. The implemented control strives to be as blended as possible, whilst still ensuring that all electric energy is used in the driving mission. The controller is adaptive to reduce the importance of correct initial values, but since the initial values affect the consumption, a method is developed to estimate the optimal initial value for the controller based on driving cycle information. This works well for most driving cycles with promising consumption results. The controller performs well in the benchmark; however, the driving cycles used show potential for improvement. A robustness built into the controller affects the consumption more than necessary, and in the case of altitude variations the control does not make use of all the energy available. The control is therefore extended to also make use of topography information that could be provided by a GPS which shows a potential further decrease in fuel consumption.

  • 142.
    Sivertsson, Martin
    et al.
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Eriksson, Lars
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Generator Effects on the Optimal Control of a Power Assisted Diesel-Electric Powertrain2013In: IEEE VPPC 2013 – The 9th IEEE Vehicle Power and Propulsion Conference, Institute of Electrical and Electronics Engineers (IEEE), 2013Conference paper (Refereed)
    Abstract [en]

    Optimal control of a diesel-electric powertrain in transient operation is studied. The attention is on how generator limits affect the solution, as well as how the addition of a small energy storage can assist in the transients. Two different types of problems are solved, minimum fuel and minimum time, with different generator limits as well as with and without an extra energy storage. In the optimization both the output power and engine speed are free variables. For this aim a 4-state mean value engine model is used together with models for the generator and energy storage losses. The considered transients are steps from idle to target power with different amounts of freedom, defined as requirements on produced energy, before the requested power has to be met. For minimum fuel transients the energy storage remains virtually unused for all requested energies, for minimum time it does not. The generator limits are found to have the biggest impact on the fuel economy, whereas an energy storage could significantly reduce the response time.

  • 143.
    Sivertsson, Martin
    et al.
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Eriksson, Lars
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Model and discretization impact on oscillatory optimal control for a diesel-electric powertrain2015In: 4th IFAC Workshop on Engine and Powertrain Control, Simulation and Modeling E-COSM 2015 Columbus, Ohio, USA, 23-26 August 2015, Elsevier, 2015, Vol. 48(15), p. 66-71Conference paper (Refereed)
    Abstract [en]

    A mean value engine model is used to study optimal control of a diesel-electric powertrain. The resulting optimal controls are shown to be highly oscillating for certain operating points, raising the question whether this is an artifact of discretization, modeling choices or a phenomenon available in real engines. Several model extensions are investigated and their corresponding optimal control trajectories are studied. It is shown that the oscillating controls cannot be explained by the implemented extensions to the previously published model, nor by the discretization, showing that for certain operating points the optimal solution is periodic.

  • 144.
    Sivertsson, Martin
    et al.
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Eriksson, Lars
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Modeling for Optimal Control: A Validated Diesel-Electric Powertrain Model2014In: Proceedings of the 55th Conference on Simulation and Modelling (SIMS 55), Modelling, Simulation and Optimization, 21-22 October 2014, Aalborg, Denmark / [ed] Alireza Rezania Kolai, Kim Sørensen & Mads Pagh Nielsen, Linköping: Linköping University Electronic Press, 2014, p. 49-58Conference paper (Refereed)
    Abstract [en]

    An optimal control ready model of a diesel-electric powertrain is developed,validated and provided to the research community. The aim ofthe model is to facilitate studies of the transient control of diesel-electricpowertrains and also to provide a model for developers of optimizationtools. The resulting model is a four state three control mean valueengine model that captures the significant nonlinearity of the diesel engine, while still being continuously differentiable.

  • 145.
    Sivertsson, Martin
    et al.
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Eriksson, Lars
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Optimal and real-time control potential of a diesel-electric powertrain2014In: Proceedings of the 19th World CongressThe International Federation of Automatic ControlCape Town, South Africa. August 24-29, 2014 / [ed] Edward Boje and Xiaohua Xia, Cape Town: International Federation of Automatic Control , 2014, Vol. 19, p. 4825-4830Conference paper (Refereed)
    Abstract [en]

    Real-time control strategies and their performance related to the optimal control trajectories for a diesel-electric powertrain in transient operation are studied. The considered transients are steps from idle to target power. A non-linear four state-three input mean value engine model, incorporating the important turbocharger dynamics, is used for this study. The strategies are implemented using the SAE J1939-standard for engine control and evaluated compared to both the optimal solution and the solution when the engine is restricted to follow its stationary optimal line. It is shown that with the control parameters tuned for a specific criteria both engine control strategies in the SAE J1939-standard, speed control and load control, can achieve almost optimal results, where engine load controlled shows a better trade-off between fuel economy and duration. The controllers are then extended and it is shown that it is possible to control the powertrain in a close to optimal way using the SAE J1939-standard, both with the engine speed and load controlled. However the mode where the engine is load controlled is seen to be more robust.

  • 146.
    Sivertsson, Martin
    et al.
    Linköping University, Department of Electrical Engineering. Linköping University, Faculty of Science & Engineering.
    Eriksson, Lars
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    Optimal Powertrain Lock-Up Transients for a Heavy Duty Series Hybrid Electric Vehicle2017In: IFAC PAPERSONLINE, ELSEVIER SCIENCE BV , 2017, Vol. 50, no 1, p. 7842-7848Conference paper (Refereed)
    Abstract [en]

    Fuel optimal lock-up transients for a heavy duty series hybrid electric vehicle are studied. A mean value engine model is used together with numerical optimal control to investigate the interplay between electric machine, gearbox and engine with its turbocharger dynamics in particular how they influence the manner and rate at which the engine should be controlled in order to reach a synchronized speed with the gear-box, enabling lock-up. This is studied both for prescribed gear-box speeds, simulating a mechanical transmission, and with gear-box speed an optimization variable, simulating a continuously variable transmission. The optimal engine transients and their duration are seen to be dictated by the stationary efficiency of the different drivetrain modes, showing that the ratio between the efficiencies of the electric and mechanical path dominates the dynamics and have a greater effect than the engine and turbocharger dynamics. In particular the transition between the modes is as fast as possible when the conventional powertrain is the most efficient and as slow as possible when the engine-generator set is more efficient. This points out that the stationary efficiency maps can be used in a central way for the control design of lock-up transients. (c) 2017, IFAC (International Federation of Automatic Control) Hosting by Elsevier Ltd. All rights reserved.

  • 147.
    Sivertsson, Martin
    et al.
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Eriksson, Lars
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Optimal Short Driving Mission Control for a Diesel-Electric Powertrain2012In: IEEE VPPC 2012 -- The 8th IEEE Vehicle Power and Propulsion Conference, IEEE , 2012, p. 413-418Conference paper (Refereed)
    Abstract [en]

    Time and fuel optimal control for a diesel-electric powertrain in transient operation is studied using a four state, three controls non-linear mean value engine model. In the studied transients the engine starts at idle and stops when the generated energy fulfills the driving mission requirement. During the driving mission both the engine speed and output power are allowed to vary, but with a constraint on power. Two strategiesare then developed and evaluated. One where the driving mission is optimized with the generator power considered a free variable,and a second strategy where the accelerating phase of the transient is first optimized and then the optimal controls fora fixed generator power are used. The time optimal control is shown to be almost as fuel efficient as the fuel optimal controleven though the gain in time is large. The time optimal control also has the advantage of using constant power output, making itsimple and easily implementable, whilst the fuel optimal control is more complex and changes with the length of the driving mission.

  • 148.
    Sivertsson, Martin
    et al.
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Eriksson, Lars
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Optimal stationary control of diesel engines using periodic control2017In: Proceedings of the Institution of mechanical engineers. Part D, journal of automobile engineering, ISSN 0954-4070, E-ISSN 2041-2991, Vol. 231, no 4, p. 457-475Article in journal (Refereed)
    Abstract [en]

    Measurements and optimal control are used to study whether the fuel economy of a diesel engine can be improved through periodic control of the wastegate, illustrating how modern optimal control tools can be used to identify non-trivial solutions that can improve performance. The measurements show that the pumping torque of the engine is changed when the wastegate is controlled in a periodic manner versus stationary even if the mean position is the same. If this decreases the fuel consumption or not is seen to be frequency and operating point dependent. The measurements indicate that the phenomenon occurs in the time scales capturable by mean value engine models (MVEM). The operating points are further analyzed using a MVEM and optimal control. It is shown that whether the optimal solution exhibits periodic oscillations or not is operating point dependent, but is not due to the instantaneous nature of the controls. Even if an actuator model is added the oscillations persist for reasonable time constants, the frequency of the oscillations is however affected. Further it is shown that the periodic control can be predicted by optimal periodic control theory and that the frequency of the control affects the resulting efficiency.

  • 149.
    Sivertsson, Martin
    et al.
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Eriksson, Lars
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Optimal Step Responses in Diesel-Electric Systems2012In: Mechatronics'12 -- The 13th Mechatronics Forum International Conference, 2012Conference paper (Refereed)
    Abstract [en]

    A non-linear four state-three input mean value engine model, incorporating the important turbocharger dynamics,is used to study optimal control of a diesel-electric powertrain during transients. The optimization is conducted for two differentcriteria, both time and fuel optimal control, and both engine speed and output power are considered free variables in theoptimization. The transients considered are steps from idle to a target power and the results of the optimization show thatthe solutions can be divided into two categories, depending on requested power. The resulting control strategies are also seento be valid for other initial conditions than idle. For steps to high power the controls for both criteria follow a similarstructure, a structure given by the maximum torque line and the smoke-limiter. The main difference between fuel and timeoptimal control is the end operating point, and how this is approached. The fuel optimal control builds more kinetic energyin the turbocharger, reducing the necessary amount of kinetic energy in the system to produce the requested power. It is foundthat the fact that it does not approach the fuel optimal operating point relates to the amount of produced energy required to getthere. For steps to low output powers the optimal controls deal with the turbocharger dynamics in a fundamentally differentway.

  • 150.
    Sivertsson, Martin
    et al.
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Eriksson, Lars
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Optimal transient control and effects of a small energy storage for a diesel-electric powertrain2013In: 7th IFAC Symposium on Advances in Automotive Control, 2013 / [ed] Taketoshi Kawabe, International Federation of Automatic Control , 2013, p. 818-823Conference paper (Refereed)
    Abstract [en]

    Optimal control of a diesel-electric powertrain in transient operation is studied. The attention is on how generator limits affect the solution, as well as how the addition of a small energy storage can assist in the transients. Two different types of problems are solved, minimum fuel and minimum time, with different generator limits as well as with and without an extra energy storage. In the optimization both the output power and engine speed are free variables. For this aim a 4-state mean value engine model is used together with models for the generator and energy storage losses. The considered transients are steps from idle to target power with different amounts of freedom, defined as requirements on produced energy, before the requested power has to be met. For minimum fuel transients the energy storage remains virtually unused for all requested energies, for minimum time it does not. The generator limits are found to have the biggest impact on the fuel economy, whereas an energy storage could significantly reduce the response time.

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