• The Transactions of the Korean Institute of Power Electronics
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• v.2 no.1
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• pp.1-11
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• 1997

In this paper, a novel multivariable state feedback control with feedforward control is proposed to improve control performance of power conversion systems. The targets of the application are three-phase voltage-source PWM converter and inverter system, and current-source PWM converter and inverter system, of which equivalent circuits and models are derived and analyzed. Various simulation results are presented to verify the validity of the proposed scheme.

• Journal of Ocean Engineering and Technology
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• v.9 no.2
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• pp.30-40
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• 1995

In this paper, it is proposed a robust control scheme for real time control of a robot manipulator with parameter uncertainties. The focus of this paper is a new approach of multivariable control schemes for an assembly robot manipulator to achieve the accurate trajectory tracking by joint angles. The proposed control scheme consists of a multivariable feedforward controller and feedback controller. In this control scheme, the feedback controller consists of proportional-derivative type and is designed by the pole placement method. The feedforward controller uses the inverse of the linealized model of robot manipulator dynamics. This feedback controller ensures that each joint enables to track any reference trajectory. The proposed robot controller scheme has a computational efficiency.

• Transactions of the Korean Society of Automotive Engineers
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• v.19 no.5
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• pp.14-21
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• 2011

In diesel engines, accurate EGR control is important due to its effect on nitrogen oxide and particulate matter emissions. Conventional EGR control system comprises a PI feedback controller for tracking target air mass flow and a feedforward controller for fast response. Physically, the EGR flow is affected by EGR valve lift and thermodynamic properties of the EGR path, such as pressures and temperatures. However, the conventional feedforward control output is indirectly derived from engine operating conditions, such as engine rotational speed and fuel injection quantity. Accordingly, the conventional feedforward control action counteracts the feedback controller in certain operating conditions. In order to improve this disadvantage, in this study, we proposed feedforward EGR control algorithm based on a physical model of the EGR system. The proposed EGR control strategy was validated with a 3.0 liter common rail direct injection diesel engine equipped with a DC motor type EGR valve.

• Proceedings of the KIEE Conference
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• 1996.07a
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• pp.312-317
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• 1996

This paper compares the output voltage control strategies of three-phase PWM inverter for uninterruptible power supply. The feedforward control, feedforward/feedback control, and decoupled feedback control in both the synchronous reference frame and the stationary reference frame are examined. In particular, it is shown that the response of the decoupled feedback controller in the synchronous reference frame can be improved by pole-zero cancellation method. It is also shown that the pole-zero cancellation method reduces to the deadbeat control, when it is implemented with digital controller.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.52 no.4
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• pp.189-197
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• 2003

The problem of designing a parallel feedforward compensator (PFC) is considered for a class of non-square linear systems such that the closed-loop system is strictly passive. If a given square system has (vector) relative degree one and is weakly minimum phase, the system can be rendered passive by a state feedback. However, when the system states are not always measurable and the given output is considered, passivation (i.e. rendering passive) of a non-minimum phase system or a system with high relative degree cannot be achieved by any other methodologies except by using a PFC. To passivate a non-square system we first determine a squaring gain matrix and design a PFC such that the composite system has relative degree one and is minimum phase. Then the system is rendered strictly passvie by a static output feedback law. Necessary and sufficient conditions for the existence of the PFC and the squaring gain matrix are given by the static output feedback formulation, which enables to utilize linear matrix inequality (LMI). As an application of the scheme, an alternative way of replacing the role of velocity measurements is provided for the PD-control law of a convey-crane system.

• Smart Structures and Systems
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• v.31 no.3
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• pp.259-273
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• 2023

Real-time hybrid simulation (RTHS) is an effective experimental technique for structural dynamic assessment. However, time delay causes displacement de-synchronization at the interface between the numerical and physical substructures, negatively affecting the accuracy and stability of RTHS. To this end, the authors have proposed a model-based adaptive control strategy with a Kalman filter (MAC-KF). In the proposed method, the time delay is mainly mitigated by a parameterized feedforward controller, which is designed using the discrete inverse model of the control plant and adjusted using the KF based on the displacement command and measurement. A feedback controller is employed to improve the robustness of the controller. The objective of this study is to further validate the power of dealing with a nonlinear control plant and to investigate the potential challenges of the proposed method through actual experiments. In particular, the effect of the order of the feedforward controller on tracking performance was numerically investigated using a nonlinear control plant; a series of actual RTHS of a frame structure equipped with a magnetorheological damper was performed using the proposed method. The findings reveal significant improvement in tracking accuracy, demonstrating that the proposed method effectively suppresses the time delay in RTHS. In addition, the parameters of the control plant are timely updated, indicating that it is feasible to estimate the control plant parameter by KF. The order of the feedforward controller has a limited effect on the control performance of the MAC-KF method, and the feedback controller is beneficial to promote the accuracy of RTHS.

• Proceedings of the KIEE Conference
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• 1991.07a
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• pp.744-747
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• 1991

In this paper, the design of optimal feedforward regulators with the optimal feedforward filters for improving power frequency deviations in an interconnected system, using a polynominal LQG approach, is proposed. The performances of the regulators with the optimal feedforward filters were compared with the frequency feedback regulator only in power system by simulation. The results show that the optimal feedforward regulators reduce the power frequency standard deviation by 25%-60% in the white noise load and the peak deviation in the step load by 8%-27%.

• The Journal of the Acoustical Society of Korea
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• v.16 no.5
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• pp.18-25
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• 1997

The feedforward control algorithm for active noise control exhibits high stability and performance robustness. But it has a slow convergence speed and requires a correlated reference signal. Broadband active control systems typically use feedback control in order to increase the convergence speed and to avoid the problems associated with obtaining and decoupling a suitable reference signal. However, it is well known that conventional feedback control systems have a gain-bandwidth limitation and stability problem. This paper presents the new system based on the combination of both feedforward and feedback system in order to increase the convergence speed. The proposed system uses a proposed control algorithm termed "optional-summed" algorithm in which the "optional summed reference signal" comprised of weighted sum of an original reference signal and a eror signal, is used as an input to an adaptive system. Thus, the proposed system can have faster convergence speed and better performance than either feedforward or feedback system using the Filtered-x LMS algorithm as almost equivalent complexity of computation as it. Several simulation results demonstrating the good properties of the proposed adaptive system as well as verifying the analytical results are also presented in the paper.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.46 no.11
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• pp.934-943
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• 2018

In these days, demand for agile spacecraft is gradually increasing, due to the fact that agile spacecraft can improve mission capability. In this paper, an attitude control logic based on reaction wheels that can enhance agility of spacecraft is proposed. Three methods are suggested, and all three or part of them can be integrated to the existing attitude control system. First, a feedforward/feedback controller is introduced, and its pros and cons are provided, compared to the conventional feedback controller. Second, an attitude command generation method that fully utilizes torque/momentum capacities of reaction wheels is proposed. Third, a torque (current) control mode for internal wheel control is introduced. Numerical results verify that the settling time can be significantly reduced by employing the feedforward/feedback control method, especially for large angle maneuver.

• Proceedings of the KIEE Conference
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• 2004.11c
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• pp.699-701
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• 2004

This paper proposes the algorithm of servo- writing based on feedback error learning neural networks. The controller consists of feedback controller using PID and feedforward controller using gaussian radial basis function network. Because the RBFNs are trained by on-line rule, the controller has adaptation capability. The performance of the proposed controller is compared to that of conventional PID controller. Proposed algorithm shows better performance than PID controller.