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In this paper, we propose an analytic solution of state-constrained optimal tracking control problems for continuous-time linear time-invariant (CT-LTI) systems that are based on model-based prediction, the quadratic penalty function, and the variational approach. Model-based prediction is a concept taken from model-predictive control (MPC) and this is essential to change the direction of calculation for the solution from backward to forward. The quadratic penalty function plays an important role in deriving the analytic solution since it can transform the problem into a form that does not have inequality constraints. For computational convenience, we also propose a sub-optimal controller derived from the steady-state approximation of the analytic solution and show that the proposed controller satisfies the Lyapunov stability. The main advantage of the proposed controller is that it can be implemented in real time with a lower computational load compared to the implicit MPC. Finally, the simulation results for a DC motor servo system are shown and compared with the results of the direct multi-shooting method and the implicit MPC to verify the effectiveness of the proposed controller.
Jihwan Kim; Ung Jon; Hyeongcheol Lee. State-Constrained Sub-Optimal Tracking Controller for Continuous-Time Linear Time-Invariant (CT-LTI) Systems and Its Application for DC Motor Servo Systems. Applied Sciences 2020, 10, 5724 .
AMA StyleJihwan Kim, Ung Jon, Hyeongcheol Lee. State-Constrained Sub-Optimal Tracking Controller for Continuous-Time Linear Time-Invariant (CT-LTI) Systems and Its Application for DC Motor Servo Systems. Applied Sciences. 2020; 10 (16):5724.
Chicago/Turabian StyleJihwan Kim; Ung Jon; Hyeongcheol Lee. 2020. "State-Constrained Sub-Optimal Tracking Controller for Continuous-Time Linear Time-Invariant (CT-LTI) Systems and Its Application for DC Motor Servo Systems." Applied Sciences 10, no. 16: 5724.
This paper presents a practical approach using disturbance observer (DOB)-based longitudinal vehicle speed control in hybrid electric vehicles (HEVs). Speed control law is derived from a linearized nominal plant model obtained assuming that the vehicle is a lumped mass. The plant uncertainty and external disturbance are lumped into a disturbance term and compensated for by the DOB. In addition, a feedforward term is designed to improve tracking performance when a target trajectory varies during acceleration and deceleration. The proposed control algorithm is validated by simulations. Vehicle experiments are performed on C-segment HEVs and D-segment plug-in HEVs. The validation results from both simulations and vehicle experiments, comparing a proportional-integral (PI) controller, show that the proposed controller is more robust to model uncertainty and external disturbance.
SangJoon Kim; Jae Sung Bang; Sungdeok Kim; Hyeongcheol Lee. Robust Vehicle Speed Control Using Disturbance Observer in Hybrid Electric Vehicles. International Journal of Automotive Technology 2020, 21, 931 -942.
AMA StyleSangJoon Kim, Jae Sung Bang, Sungdeok Kim, Hyeongcheol Lee. Robust Vehicle Speed Control Using Disturbance Observer in Hybrid Electric Vehicles. International Journal of Automotive Technology. 2020; 21 (4):931-942.
Chicago/Turabian StyleSangJoon Kim; Jae Sung Bang; Sungdeok Kim; Hyeongcheol Lee. 2020. "Robust Vehicle Speed Control Using Disturbance Observer in Hybrid Electric Vehicles." International Journal of Automotive Technology 21, no. 4: 931-942.
Most vehicle controllers are developed and verified with V-model. There are several traditional methods in the automotive industry called “X-in-the-Loop (XIL)”. However, the validation of advanced driver assistance system (ADAS) controllers is more complicated and needs more environmental resources because the controller interacts with the external environment of the vehicle. Vehicle-in-the-Loop (VIL) is a recently being developed approach for simulating ADAS vehicles that ensures the safety of critical test scenarios in real-world testing using virtual environments. This new test method needs both properties of traditional computer simulations and real-world vehicle tests. This paper presents a Vehicle-in-the-Loop topology for execution in global Coordinates system. Also, it has a modular structure with four parts: synchronization module, virtual environment, sensor emulator and visualizer, so each part can be developed and modified separately in combination with other parts. This structure of VIL is expected to save maintenance time and cost. This paper shows its acceptability by testing ADAS on both a real and the VIL system.
Changwoo Park; Seunghwan Chung; Hyeongcheol Lee. Vehicle-in-the-Loop in Global Coordinates for Advanced Driver Assistance System. Applied Sciences 2020, 10, 2645 .
AMA StyleChangwoo Park, Seunghwan Chung, Hyeongcheol Lee. Vehicle-in-the-Loop in Global Coordinates for Advanced Driver Assistance System. Applied Sciences. 2020; 10 (8):2645.
Chicago/Turabian StyleChangwoo Park; Seunghwan Chung; Hyeongcheol Lee. 2020. "Vehicle-in-the-Loop in Global Coordinates for Advanced Driver Assistance System." Applied Sciences 10, no. 8: 2645.
This paper proposes a novel supervisory control for a parallel hybrid electric vehicles (HEVs) with a transmission-mounted electric drive (TMED). The proposed control includes an optimal power distribution algorithm that uses a modified equivalent consumption minimization strategy (ECMS) and an optimal mode determination algorithm based on the state machine framework. The control vector of the proposed ECMS is expanded to two degrees of freedom to determine the power-split ratios of the TMED HEV, and the cost function is re-defined in accordance with the target system. A new mode-transition algorithm is also proposed to prevent the occurrence of frequent mode transitions as well as improve fuel economy and drivability. Simulation results demonstrate the validity and performance of the proposed control algorithms.
Taeho Park; Hyeongcheol Lee. Optimal Supervisory Control Strategy for a Transmission-Mounted Electric Drive Hybrid Electric Vehicle. International Journal of Automotive Technology 2019, 20, 663 -677.
AMA StyleTaeho Park, Hyeongcheol Lee. Optimal Supervisory Control Strategy for a Transmission-Mounted Electric Drive Hybrid Electric Vehicle. International Journal of Automotive Technology. 2019; 20 (4):663-677.
Chicago/Turabian StyleTaeho Park; Hyeongcheol Lee. 2019. "Optimal Supervisory Control Strategy for a Transmission-Mounted Electric Drive Hybrid Electric Vehicle." International Journal of Automotive Technology 20, no. 4: 663-677.
This paper proposes a DC motor current control algorithm using a proportional-integral linear quadratic tracking (LQT) controller with a disturbance observer for the electronic stability control (ESC) brake system. Previously researched algorithms related to current control using disturbance rejection are robust control, adaptive control, LQT, or proportional-integral disturbance observer (PI-DOB); each of them has both advantages and disadvantages. The proposed algorithm uses a disturbance observer in order to improve disturbance rejection performance while avoiding the drawbacks of high gain property. Additionally, the proposed algorithm adds integral control in order to improve performance in the low frequency bands. In order to assess the performance of the proposed algorithm, simulations and experiments are performed in the time and frequency domains to compare the proposed algorithm with different algorithms which are actually implemented into the ESC. The proposed algorithm shows good characteristics near the cut-off frequency, which can be confirmed clearly by the time domain results.
Ung Jon; Jihwan Kim; Hyeongcheol Lee. DC Motor Current Control Algorithm Using Proportional-Integral LQT with Disturbance Observer. International Journal of Automotive Technology 2018, 19, 959 -967.
AMA StyleUng Jon, Jihwan Kim, Hyeongcheol Lee. DC Motor Current Control Algorithm Using Proportional-Integral LQT with Disturbance Observer. International Journal of Automotive Technology. 2018; 19 (6):959-967.
Chicago/Turabian StyleUng Jon; Jihwan Kim; Hyeongcheol Lee. 2018. "DC Motor Current Control Algorithm Using Proportional-Integral LQT with Disturbance Observer." International Journal of Automotive Technology 19, no. 6: 959-967.
Vehicle control systems such as ESC (electronic stability control), MDPS (motor-driven power steering), and ECS (electronically controlled suspension) improve vehicle stability, driver comfort, and safety. Vehicle control systems such as ACC (adaptive cruise control), LKA (lane-keeping assistance), and AEB (autonomous emergency braking) have also been actively studied in recent years as functions that assist drivers to a higher level. These DASs (driver assistance systems) are implemented using vehicle sensors that observe vehicle status and send signals to the ECU (electronic control unit). Therefore, the failure of each system sensor affects the function of the system, which not only causes discomfort to the driver but also increases the risk of accidents. In this paper, we propose a new method to detect and isolate faults in a vehicle control system. The proposed method calculates the constraints and residuals of 12 systems by applying the model-based fault diagnosis method to the sensor of the chassis system. To solve the inaccuracy in detecting and isolating sensor failure, we applied residual sensitivity to a threshold that determines whether faults occur. Moreover, we applied a sensitivity analysis to the parameters semi-correlation table to derive a fault isolation table. To validate the FDI (fault detection and isolation) algorithm developed in this study, fault signals were injected and verified in the HILS (hardware-in-the-loop simulation) environment using an RCP (rapid control prototyping) device.
Wonbin Na; Changwoo Park; Seokjoo Lee; Seongo Yu; Hyeongcheol Lee. Sensitivity-Based Fault Detection and Isolation Algorithm for Road Vehicle Chassis Sensors. Sensors 2018, 18, 2720 .
AMA StyleWonbin Na, Changwoo Park, Seokjoo Lee, Seongo Yu, Hyeongcheol Lee. Sensitivity-Based Fault Detection and Isolation Algorithm for Road Vehicle Chassis Sensors. Sensors. 2018; 18 (8):2720.
Chicago/Turabian StyleWonbin Na; Changwoo Park; Seokjoo Lee; Seongo Yu; Hyeongcheol Lee. 2018. "Sensitivity-Based Fault Detection and Isolation Algorithm for Road Vehicle Chassis Sensors." Sensors 18, no. 8: 2720.
An integrated fault-diagnosis algorithm for a motor sensor of in-wheel independent drive electric vehicles is presented. This paper proposes a method that integrates the high- and low-level fault diagnoses to improve the robustness and performance of the system. For the high-level fault diagnosis of vehicle dynamics, a planar two-track non-linear model is first selected, and the longitudinal and lateral forces are calculated. To ensure redundancy of the system, correlation between the sensor and residual in the vehicle dynamics is analyzed to detect and separate the fault of the drive motor system of each wheel. To diagnose the motor system for low-level faults, the state equation of an interior permanent magnet synchronous motor is developed, and a parity equation is used to diagnose the fault of the electric current and position sensors. The validity of the high-level fault-diagnosis algorithm is verified using Carsim and Matlab/Simulink co-simulation. The low-level fault diagnosis is verified through Matlab/Simulink simulation and experiments. Finally, according to the residuals of the high- and low-level fault diagnoses, fault-detection flags are defined. On the basis of this information, an integrated fault-diagnosis strategy is proposed.
Namju Jeon; Hyeongcheol Lee. Integrated Fault Diagnosis Algorithm for Motor Sensors of In-Wheel Independent Drive Electric Vehicles. Sensors 2016, 16, 2106 .
AMA StyleNamju Jeon, Hyeongcheol Lee. Integrated Fault Diagnosis Algorithm for Motor Sensors of In-Wheel Independent Drive Electric Vehicles. Sensors. 2016; 16 (12):2106.
Chicago/Turabian StyleNamju Jeon; Hyeongcheol Lee. 2016. "Integrated Fault Diagnosis Algorithm for Motor Sensors of In-Wheel Independent Drive Electric Vehicles." Sensors 16, no. 12: 2106.
The sideslip driving status is of fundamental importance to the stability of a vehicle. This paper presents a practical vehicle sideslip driving status estimation method that uses ESP (electronic stability program) sensors. ESP sensors such as wheel speed, lateral acceleration, yaw rate and steering wheel angle sensors are used to determine the sideslip driving status and distinguish a banked road. This estimation algorithm contains front-rear sideslip and banked road detection methods. The proposed sideslip estimation algorithm was designed to use the analytical redundancy of these sensors and Lagrange interpolation methods. The performance and effectiveness of the proposed estimation and compensation algorithm were investigated using vehicle tests. This paper presents the results of two cases that were used for the experimental verification: a curved flat road and banked road.
S. Chung; H. Lee. Vehicle sideslip estimation and compensation for banked road. International Journal of Automotive Technology 2016, 17, 63 -69.
AMA StyleS. Chung, H. Lee. Vehicle sideslip estimation and compensation for banked road. International Journal of Automotive Technology. 2016; 17 (1):63-69.
Chicago/Turabian StyleS. Chung; H. Lee. 2016. "Vehicle sideslip estimation and compensation for banked road." International Journal of Automotive Technology 17, no. 1: 63-69.
This paper presents a motor position control algorithm for an automated manual transmission (AMT) of the agricultural tractor, based on modified linear quadratic tracking (LQT). In this paper, the modified LQT is derived from the conventional LQT by applying the Luenberger observer in order to design an output feedback controller. A dynamic model of the actuator is derived to represent characteristics of the worm geared DC motor and the proposed control algorithm is applied and tuned with the model. The proposed position control algorithm of the worm geared motor using the modified LQT can improve disturbance rejection performance without changing the hardware configuration of the AMT. The simulation results show the validity of the proposed control algorithm.
Jihwan Kim; Hyeongcheol Lee. Motor position control algorithm for an automated manual transmission of the agricultural tractor. Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 2015, 229, 3341 -3349.
AMA StyleJihwan Kim, Hyeongcheol Lee. Motor position control algorithm for an automated manual transmission of the agricultural tractor. Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science. 2015; 229 (18):3341-3349.
Chicago/Turabian StyleJihwan Kim; Hyeongcheol Lee. 2015. "Motor position control algorithm for an automated manual transmission of the agricultural tractor." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 229, no. 18: 3341-3349.
This paper describes the development process and results of a battery system model with a fault simulation for electric propulsion vehicles. The developed battery system model can be used to verify control and fault diagnosis strategies of the supervisory controller in an electric propulsion vehicle. To develop this battery system model, three sub-models, including a battery model, a relay assembly model, and a battery management system (BMS) model, are connected together like in the target real battery system. Comparison results between the real battery system hardware and the battery system model show a similar tendency and values. Furthermore, the fault injection test of the model shows that the proposed battery system model can simulate a failure situation consistent with a real system. It is possible for the model to emulate the battery characteristics and fault situation if it is used in the development process of a BMS or for supervisory control strategies for electric propulsion systems.
Hyeongjin Ham; Kyuhong Han; Hyeongcheol Lee. Battery System Modeling for a Military Electric Propulsion Vehicle with a Fault Simulation. Energies 2013, 6, 5168 -5181.
AMA StyleHyeongjin Ham, Kyuhong Han, Hyeongcheol Lee. Battery System Modeling for a Military Electric Propulsion Vehicle with a Fault Simulation. Energies. 2013; 6 (10):5168-5181.
Chicago/Turabian StyleHyeongjin Ham; Kyuhong Han; Hyeongcheol Lee. 2013. "Battery System Modeling for a Military Electric Propulsion Vehicle with a Fault Simulation." Energies 6, no. 10: 5168-5181.
Jihwan Kim; Yunsung Goo; Hyeongcheol Lee. Signal-based Fault Diagnosis Algorithm of Control Surfaces of Small Fixed-wing Aircraft. Journal of the Korean Society for Aeronautical & Space Sciences 2012, 40, 1040 -1047.
AMA StyleJihwan Kim, Yunsung Goo, Hyeongcheol Lee. Signal-based Fault Diagnosis Algorithm of Control Surfaces of Small Fixed-wing Aircraft. Journal of the Korean Society for Aeronautical & Space Sciences. 2012; 40 (12):1040-1047.
Chicago/Turabian StyleJihwan Kim; Yunsung Goo; Hyeongcheol Lee. 2012. "Signal-based Fault Diagnosis Algorithm of Control Surfaces of Small Fixed-wing Aircraft." Journal of the Korean Society for Aeronautical & Space Sciences 40, no. 12: 1040-1047.
This paper presents a new robust road bank angle estimation method that does not require a differential global positioning system or any additional expensive sensors. A modified bicycle model, which is less sensitive to model uncertainties than is the conventional bicycle model, is proposed. The road bank angle estimation algorithm designed using this model can improve robustness against modelling errors and uncertainties. A proportional–integral H ∞ filter based on the game theory approach, which is designed for the worst cases with respect to the sensor noises and disturbances, is used as the estimator in order to improve further the stability and robustness of the bank estimation. The effectiveness and performance of the proposed estimation algorithm are verified by simulations and tests, and the results are compared with those of previous road bank angle estimation methods.
Jihwan Kim; Hyeongcheol Lee; Seibum Choi. A robust road bank angle estimation based on a proportional–integral H∞ filter. Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 2012, 226, 779 -794.
AMA StyleJihwan Kim, Hyeongcheol Lee, Seibum Choi. A robust road bank angle estimation based on a proportional–integral H∞ filter. Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering. 2012; 226 (6):779-794.
Chicago/Turabian StyleJihwan Kim; Hyeongcheol Lee; Seibum Choi. 2012. "A robust road bank angle estimation based on a proportional–integral H∞ filter." Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 226, no. 6: 779-794.
This paper presents a new fault-tolerant control (FTC) algorithm for an automotive air suspension control (ASC) system. The FTC algorithm proposed in this paper provides the fault detection, diagnosis, and management of a closed-loop air suspension control system. A new model-based fault detection and isolation algorithm for the height sensors, which are critical but vulnerable components of the ASC system, is also proposed. The height sensor fault is detected on the basis of the geometric relationships of the suspension and is isolated by implementing the analytical redundancy of the height sensors using roll and pitch angle estimates derived by a Kalman filter. An adaptive threshold is designed and applied in order to enhance the robustness of the fault detection and isolation against model uncertainties. The effectiveness of the proposed model-based FTC algorithm is verified via simulation and actual vehicle tests.
Hyunsup Kim; Hyeongcheol Lee. Model-based fault-tolerant control for an automotive air suspension control system. Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 2011, 225, 1462 -1480.
AMA StyleHyunsup Kim, Hyeongcheol Lee. Model-based fault-tolerant control for an automotive air suspension control system. Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering. 2011; 225 (11):1462-1480.
Chicago/Turabian StyleHyunsup Kim; Hyeongcheol Lee. 2011. "Model-based fault-tolerant control for an automotive air suspension control system." Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 225, no. 11: 1462-1480.
This paper presents an analytical sensor fault-detection and isolation algorithm for the vertical accelerometers of a continuous damping control (CDC) system, which are essential but vulnerable components in the CDC system. Because the sensor configuration of the target CDC system does not provide sufficient redundancy for fault diagnosis, two different vehicle suspension models, a modified full car model and a roll-and-pitch plane model, are derived and combined to establish analytical redundancy. Parity equations for the vertical motion of a sprung mass are derived using the combined model and applied in order to detect faults of the vertical accelerometers. In order to isolate the faults properly in practical situations, this paper proposes a fault isolation algorithm which calculates estimates of the vertical acceleration at the centre of gravity of the sprung mass using vertical acceleration signals and compares the residuals of these estimates. This paper also provides a detailed analysis regarding the detectability and isolability of vertical accelerometer faults. An adaptive threshold method is proposed to improve the performance of the suggested fault-detection and isolation algorithm. Simulation and test results demonstrate the feasibility and effectiveness of the proposed algorithm.
Jihwan Kim; Hyeongcheol Lee. Sensor fault detection and isolation algorithm for a continuous damping control system. Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 2011, 225, 1347 -1364.
AMA StyleJihwan Kim, Hyeongcheol Lee. Sensor fault detection and isolation algorithm for a continuous damping control system. Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering. 2011; 225 (10):1347-1364.
Chicago/Turabian StyleJihwan Kim; Hyeongcheol Lee. 2011. "Sensor fault detection and isolation algorithm for a continuous damping control system." Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 225, no. 10: 1347-1364.