• Transactions of the Society of Information Storage Systems
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• v.3 no.1
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• pp.5-12
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• 2007

This paper investigates the design of disturbance observer for rotational vibration suppression in disk drive systems. The design aims to provide an optimal controller which satisfies both vibration performance and robust stability. It consists of an inversion method, a special filter, and optimization scheme. Firstly a new inversion method is introduced, which provides more accurate inversion compared to conventional zero phase error method. The inversion is to deal with unstable zeros in the plant model. Secondly a special filter for disturbance selection is given, which features adjustable gain and band pass characteristics so that it enables flexible shaping of the loop considering the trade-off between performance and stability margins. And finally the parameters of disturbance observer are optimized in conjunction with external disturbance model. Simulation and experiment on commercial hard disk drives confirm that the design is very effective to such disturbance which is hard to be handled by conventional approach.

• Journal of Power Electronics
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• v.13 no.6
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• pp.975-984
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• 2013

This paper proposes a robust optimal nonlinear control with an observer to reject the offset errors of position tracking for surface mounted permanent magnet synchronous motors. We provide the control method to reject offset errors and load torque for designing field oriented control (FOC) based the alternating current (AC) frame. The proposed method consists of a torque generator, a commutation scheme, an electrical controller, and a load torque observer. The mechanical controller is designed to compensate for load torque and the offset error and generate the desired torque. The commutation scheme is proposed to create the desired currents for the desired torque. The electrical controller is developed to guarantee the desired currents. The observer is designed to estimate both the velocity and the load torque. In order to obtain the robustness to parameter uncertainties and a gain tuning guide, the linear quadratic regulator method is applied to the proposed method. The closed-loop stability is proven. A detailed process for the FOC design and an analysis of the control methods based on the AC frame are presented. The performance of the proposed method was validated via experiments. The proposed method obtains the FOC based on the AC frame. Furthermore, the position tracking performance of the proposed method is superior to that of the conventional method.

• 제어로봇시스템학회:학술대회논문집
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• 1986.10a
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• pp.113-118
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• 1986

The feedback controllers for the active vibration control of elastic systems are developed using optimal regulator, optimal tracking, time optimal and noise observer algorithms. Using the modal analysis of the elastic systems, the effects of the actuator positions, the input weighting factor and the magnitude of the constraint of the actuator force are investigated.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.20 no.5
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• pp.589-597
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• 2011

In this paper, optimal tuning of a cross-coupled controller linked with the feedforward controller and the disturbance observer is studied to improve contouring and tracking accuracy as well as robustness against disturbance. Previously developed integrated design and optimal tuning methods are applied for developing the robust tuning method. Strict mathematical modeling of the multivariable system is formulated as a state-space equation. Identification processes of the servomechanism are conducted for mechanical servo models. An optimal tuning problem to minimize both the contour error and settling time is formulated as a nonlinear constrained optimization problem including the relevant controller parameters of the servo control system. Constraints such as relative stability, robust stability and overshoot, etc. are considered for the optimization. To verify the effectiveness of the proposed optimal tuning procedure, linear and circular motion experiments are performed on the xy-table. Experimental results confirm the control performance and robustness despite the variation of parameters of the mechanical subsystems.

• Smart Structures and Systems
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• v.20 no.1
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• pp.1-10
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• 2017

Ionic Polymer Metal Composite (IPMC) is an electroactive polymer (EAP) and a promising candidate actuator for various potential applications mainly due to its flexible, low voltage/power requirements, small and compact design, and lack of moving parts. Although widely used in industry, this material requires accurate numerical models and knowledge of optimal control methods. This paper presents State-Dependent Riccati Equation (SDRE) approach as one of rapidly emerging methodologies for designing nonlinear controllers. Additionally, the present paper describes a novel method of Multi HGO Observer design. In the proposed design, the calculated position of the IPMC strip accurately tracks the target position, which is illustrated by the experiments. Numerical results and comparison with experimental data are presented and the effectiveness of the proposed control strategy is verified in experiments.

• 제어로봇시스템학회:학술대회논문집
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• 1991.10a
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• pp.1-6
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• 1991

This paper is concerned with the design of a robust tracking controller using a state observer on a robotic manipulator under the disturbance. The controller is designed to follow a step or ramp reference input without steady state error in the presence of a disturbance and a system parameter variation. In most cases, since all the state vectors are not measured, unmeasurable state vectors must be estimated or reconstructed. A reduced order observer is proposed to estimate unmeasurable state vectors of the non-linear system. Some problems are caused by the Coulomb friction, the disturbance, and the spring effect of a link between the drive motor and the manipulator arm. The state variables, directly measured and estimated by the reduced order observer, are fed back to the controller. When the robot system exhibits the 'limit cycle, the feedback gains initially obtained by optimal control theory are changed. As a result, the limit cycle is eliminated by the new controller gains,

• Journal of the Korean Society for Precision Engineering
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• v.18 no.10
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• pp.161-167
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• 2001

This paper presents an approach to nonlinear engine idle controller and intake manifold absolute pressure(MAP) observer based on mean torque production model. A stable engine idle speed is important in that the unstable engine Idle mode can make engine to drooping or stall state. A sliding fuzzy controller has been designed to control engine idle speed under load disturbance. A sliding observer is also developed to estimate the intake manifold absolute pressure and compared with the actual MAP sensor value. The sliding mode observer has shown good robustness and good tracking performance. The inputs of sliding fuzzy controller are the errors of rpm and MAP. The output is a duty cycle(DC) for driving a idle speed control valve(ISCV).

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.495-495
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• 2000

The Stewart platform manipulator is a closed-kinematis chain robot manipulator that is capable of providing high st겨ctural rigidity and positional accuracy. However, this is a complex structure, so controllability of the system is not so good. In this paper, it introduces a new robust motion control algorithm using partial state feedback for a class of nonlinear systems in the presence of modelling uncertainties and external disturbances. The major contribution of this work introduces the development and design of robust observer for the slate and the perturbation w.hich is integrated into a variable structure controller(VSC) structure. The combination of controller/observer gives rise to the robust routine called sliding mode control with sliding perturbation observer(SMCSPO). The optimal gains of SMCSPO are easily obtained by genetic algorithm. Simulation and experiment are presented in order to apply to the stewart platform manipulator. There results show highly' accuracy and performance.

• Journal of Electrical Engineering and Technology
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• v.13 no.4
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• pp.1740-1751
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• 2018

This paper proposes a novel fault tolerant tracking control (FTTC) scheme for a class of nonlinear systems with actuator failures based on the policy iteration (PI) algorithm and the adaptive fault observer. The estimated actuator failure from an adaptive fault observer is utilized to construct an improved performance index function that reflects the failure, regulation and control simultaneously. With the help of the proper performance index function, the FTTC problem can be transformed into an optimal control problem. The fault tolerant tracking controller is composed of the desired controller and the approximated optimal feedback one. The desired controller is developed to maintain the desired tracking performance at the steady-state, and the approximated optimal feedback controller is designed to stabilize the tracking error dynamics in an optimal manner. By establishing a critic neural network, the PI algorithm is utilized to solve the Hamilton-Jacobi-Bellman equation, and then the approximated optimal feedback controller can be derived. Based on Lyapunov technique, the uniform ultimate boundedness of the closed-loop system is proven. The proposed FTTC scheme is applied to reconfigurable manipulators with two degree of freedoms in order to test the effectiveness via numerical simulation.

• Journal of IKEEE
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• v.26 no.4
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• pp.596-601
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• 2022

The application of the EGR system is increasing according to the recent trend of conversion to green-ships. EGR blower, one of the core parts of the EGR, consists of aerodynamic system and e-motor and inverter and etc. For the e-motor, a permanent magnet type synchronous motor with high energy density and excellent efficiency is applied recently. Small and medium-sized enterprises trying to develop the e-motors, however, for marine inverters mostly developed by global advanced companies due to the rigid classification certification and technical difficulties. One of disadvantage of universal inverters is that when optimal control fails, it is difficult to find the cause from user's point of view. Therefore, in this study, optimal controllers(Current vector contol and Tracking observer) for SPMSM for EGR blower was designed and verified to analyze the causes of failure of optimal control of universal inverter.