• Proceedings of the KIEE Conference
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• 1996.07a
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• pp.270-273
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• 1996

A scheme of observer-based MFAC(Model Following Acceleration Control) system is proposed for the robustness control of DC servo position control systems. The proposed system is composed of LMFC, variable structure feedback controller, and reduced-order state observer. As the servo motor is controlled by the acceleration command, the total servo system becomes the acceleration control system. Simulation results show that the proposed system have robust properties against parameter variations and external disturbances.

• Proceedings of the KIEE Conference
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• 1995.07a
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• pp.261-264
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• 1995

A scheme of observer-based MFAC(Model Following Acceleration Control) system is proposed for the DC servo position control system. The proposed system is competed of MFAC, feedback controller, and reduced-order state observer. As the servo motor is controlled by the acceleration command, the total servo system becomes the acceleration control system. Simulation results show that the proposed system have robust properties against parameter variations and external disturbances.

• 제어로봇시스템학회:학술대회논문집
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• 1996.10b
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• pp.892-895
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• 1996

An unknown input observer is proposed that can be used in wheelbase preview control of commercial vehicles. The preview and state information, required to calculate actuator force, are reconstructed from the measurement variables such as heave and pitch acceleration. Gain matrix of observer is optimally selected so that influence of system and measurement noises on the estimation error can be minimized. Estimated preview information requires low pass filtering to eliminate high frequency components resulting from differentiation of noisy output signals. Effectiveness of the proposed method is demonstrated by numerical simulation of half car model.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.26 no.2
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• pp.61-67
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• 2018

This paper presents a method to apply disturbance observer to PID controller for robustness enhancement of UAVs. The system uncertainties and disturbances bring adverse effects on performance and stability of UAVs. In this paper, we estimate the acceleration disturbances using nonlinear disturbance observer, then compensate disturbances with composite controller. By employing nonlinear disturbance observer and composite controller, we have better performance and robustness than conventional PID controller. The asymptotical stability of nonlinear disturbance observer is presented through theoretical analysis. The estimation performance of nonlinear disturbance observer is evaluated by numerical simulation. And performance of disturbance observer based PID controller is evaluated by comparing the performance with conventional PID controller.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.41 no.10
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• pp.931-940
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• 2017

This paper describes a predictive fault diagnosis algorithm for autonomous vehicles based on a kinematic model that uses a sliding mode observer. To ensure the safety of autonomous vehicles, reliable information about the environment and vehicle dynamic states is required. A predictive algorithm that can interactively diagnose longitudinal environment and vehicle acceleration information is proposed in this paper to evaluate the reliability of sensors. To design the diagnosis algorithm, a longitudinal kinematic model is used based on a sliding mode observer. The reliability of the fault diagnosis algorithm can be ensured because the sliding mode observer utilized can reconstruct the relative acceleration despite faulty signals in the longitudinal environment information. Actual data based performance evaluations are conducted with various fault conditions for a reasonable performance evaluation of the predictive fault diagnosis algorithm presented in this paper. The evaluation results show that the proposed diagnosis algorithm can reasonably diagnose the faults in the longitudinal environment and acceleration information for all fault conditions.

• Journal of Auto-vehicle Safety Association
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• v.13 no.1
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• pp.14-25
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• 2021

This paper presents a RLS based adaptive sliding mode observer (A-SMO) for unknown fault reconstruction in longitudinal autonomous driving. Securing the functional safety of autonomous vehicles from unexpected faults of sensors is essential for avoidance of fatal accidents. Because the magnitude and type of the faults cannot be known exactly, the RLS based A-SMO for unknown acceleration fault reconstruction has been designed with relationship function in this study. It is assumed that longitudinal acceleration of preceding vehicle can be obtained by using the V2V (Vehicle to Vehicle) communication. The kinematic model that represents relative relation between subject and preceding vehicles has been used for fault reconstruction. In order to reconstruct fault signal in acceleration, the magnitude of the injection term has been adjusted by adaptation rule designed based on MIT rule. The proposed A-SMO in this study was developed in Matlab/Simulink environment. Performance evaluation has been conducted using the commercial software (CarMaker) with car-following scenario and evaluation results show that maximum reconstruction error ratios exist within range of ±10%.

• Journal of Institute of Control, Robotics and Systems
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• v.19 no.5
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• pp.462-467
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• 2013

This paper presents a modified disturbance observer (MDOB) for controlling two arms of a manipulator designed for a home service robot. The MDOB is slightly different from the original DOB in that it uses an accelerometer to measure acceleration of the robot arm. Then it uses the acceleration to estimate the disturbance to cancel out in the control loop. Relying on the acceleration information of the robot arm, a partial model-based control structure is formed. Experimental studies of position control of 2 DOF robot arm are conducted to evaluate the performance of the proposed position control by an MDOB method.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2001.11a
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• pp.130-134
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• 2001

In the re-entry control system, errors apt to induce because the time derivative of drag acceleration is analytically estimated. Still more, the difficulty of estimation of the exact drag coefficient in hypersonic velocity and the nun-reality of the scale height cause a steady-state drag error. This paper proposes the additional method of the disturbance observer. This reduces the steady-state drag error according to the following series. First, this method estimates a error in drag acceleration time derivative by the analytic calculation and then creates the new drag acceleration time derivative using the estimated error. The performance of the re-entry control system is verified about 32 reference trajectories.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.64 no.3
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• pp.451-457
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• 2015

In this paper, we consider the observer design problem that truly reflects the nonlinear stiffness of the manipulators. The two key ideas of our design are that (a) estimation error dynamics of the manipulator equipped with accelerometer dose not dependent on nonlinearities at the link part, when the measured signals are the motor position and the output of the accelerometer and (b) the nonlinear stiffness is indeed a Lipschitz function. In order to effectively compensate the nonlinear stiffness, the gain of the proposed observer is carefully chosen from the ARE(algebraic Riccati equations) which depend on Lipschitz constant. Comparative simulation result verifies the effectiveness of the proposed solution.

• 제어로봇시스템학회:학술대회논문집
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• 1997.10a
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• pp.289-292
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• 1997

In this paper, a continuous sliding mode controller for robot manipualator is proposed. The proposed scheme guarantees that the tracking error converges to zero maintaining the smoothness of the actual control signal. In order to estimate the acceleration data, a sliding mode observer is used, and the stability of the closed-loop system is shown.