• The Transactions of the Korean Institute of Electrical Engineers
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• v.38 no.1
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• pp.60-67
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• 1989

In this paper, a methodology is developed to remove the high frequency chattering phenomenon which is the common drawbacks of variable structure control(VSC) system. An improved control law is proposed to achieve continuous control input whose terms are continuous functions during the control process under switching plane, which removes chattering and is robust as well. The methodology developed in this paper is applied to attitude control for spacecraft and the simulated results are compared with those of typical VSC methodology.

• Proceedings of the KIEE Conference
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• 2003.07d
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• pp.2193-2196
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• 2003

기존의 멀티레이트 입력 (MRIC) 제어기는 제어 입력신호에 채터링 현상이 발생하여 추종응답에 리플이 발생하는 문제점이 있다. 이러한 리플현상을 해결하기 위해 피드포워드 보상기를 이용하여 이런 리플현상을 제거하는 방법이 제시되기도 하였다. 본 논문에서는 상태 공간에서 현재 추종기를 기반으로 리프팅 기법을 이용한 멀티레이트 입력제어기 설계를 소개한다. 본 제어기를 사용함으로써 제어입력 신호가 채터링이 생기지않음을 이산전달함수 관점에서 최종치 정리를 이용하여 증명한다.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.1636-1637
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• 2007

The sliding mode controller(SMC) is very famous controller for nonlinear control. However the SMC has a defect which is chattering problem. In this paper, we introduce the novel method which reduce the chattering problem. And we compare the performance with conventional methods, such as using low pass filter(LPF), boundary layer approach.

• Aerospace Engineering and Technology
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• v.12 no.2
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• pp.108-117
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• 2013

The oxidizer shutoff valve of a gas generator controls the mass flow rate of the propellant of a rocket engine using pilot pressure and spring the force of the valve. The developing oxidizer shutoff valve can be shut off if the pilot pressure is removed from the actuator. Therefore, force balancing is necessary to analyze the characteristics of the forces with respect to the opening and closing of the valve in order to evaluate its performance. In light of this, the valve has been designed to adjust the control pressure required to open the poppet and to determine the working fluid pressure at which the valve starts to close. Under cryogenic flow test as a tests level of C.R.T(Control Random Test), the chattering phenomena occurred due to much leakage of a metal seat section. The pressure for chattering of the oxidizer valve is predicted at about 11 bar using force balancing analysis.

• Journal of Aerospace System Engineering
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• v.12 no.1
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• pp.1-9
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• 2018

In this study, a hybrid control method that adjusts for the existing force control technique has been presented for consideration. The proposed hybrid control technique does away with the chattering phenomenon occurring in existing force control technique and provides high shock absorption efficiency. In order to design the controller for the landing gear with MR damper, the equation of motion of the landing gear was derived. The hybrid controller was designed after constructing a simulation model using Recur-Dyne, multi-body dynamic analysis software. The hybrid controller can reduce the maximum strut force and displacement based on the skyhook controller, and is able to get the high efficiency by making it work for the additional force control technique. In addition, an effective switching control technique and input shaping technique was applied to prevent the chattering in the drop simulation. Finally, the performance of the landing characteristics was evaluated throughout the various drop simulations.

• Journal of the Institute of Convergence Signal Processing
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• v.23 no.4
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• pp.185-193
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• 2022

This paper proposes an adaptive sliding mode control with radial basis function neural network(RBFNN) scheme to enhance the performance of position and attitude tracking control of quadrotor UAV. The RBFNN is utilized on the approximation of nonlinear function in the UAV dynmic model and the weights of the RBFNN are adjusted online according to adaptive law from the Lyapunov stability analysis to ensure the state hitting the sliding surface and sliding along it. In order to compensate the network approximation error and eliminate the existing chattering problems, the sliding mode control term is adjusted by adaptive laws, which can enhance the robust performance of the system. The simulation results of the proposed control method confirm the effectiveness of the proposed controller which applied for a nonlinear quadrotor UAV is presented. Form the results, it's shown that the developed control system is achieved satisfactory control performance and robustness.

• Journal of Institute of Control, Robotics and Systems
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• v.7 no.5
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• pp.393-398
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• 2001

This paper presents a new method with time-varying boundary layer and input gain, variated by Fuzzy Logic Control(FLC) by means of the system state in Sliding Mode Control (SMC). In addition to the time-varying boundary layer, the time-varying range of the fuzzy membership function has an effect on not only chattering reduction but also fast response characteristics. On the basis of SMC with time-varying boundary and FLC with time-varying input and output range, a computer simulation for inverted pendulum results in elimination of the chattering phenomenon and fast response.

• Journal of Advanced Marine Engineering and Technology
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• v.22 no.3
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• pp.328-336
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• 1998

Marine reduction gears are usually used to increase the propulsion efficiency of propellers for ships powered by medium and small sized high speed diesel engines. Most of shaft systems adopt flexible couplings to absorb the transmitted vibratory torque from the engines to the reduction gears and to prevent the chattering phenomenon of reduction gears. However some elastic couplings show non-linear characteristics due to the variable torque transmitted from the main engines and the change of ambient temperature. In this study dynamic characteristics of flexible couplings sare investigated and their effects upon various vibratory conditions of propulsion systems are clarified. A calculation program of torsional vibration for the propulsion systems are clarified. A calculation program of Results of the program developed are compared with ones of the existing linear method and propulsion systems with the elastic couplings the transfer matrix method is adopted which is found to give satisfied results.

• Journal of Ocean Engineering and Technology
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• v.12 no.2 s.28
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• pp.130-138
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• 1998

본 논문은 AUV의 수직면 운동제어를 수행하기 위하여 의사 슬라이딩 모드 제어기를 이용한 모델링 기법과 제어기 설계법에 관한 것으로서, 샘플링 간격이 길어지는 경우에도 시스템의 강인성이 확보되며 심도 제어가 안정적으로 수행되는 실용성을 실험과 수치 해석을 통하여 검증하였다. 제어기는 참고문헌에서 제안한 방법을 이용하였으며, 한국기계연구원 선박해양공학연구센터(KRISO)에서 개발한 VORAM호를 제어 대상 AUV로 선정하였다. PMM 시험으로 얻어진 운동 계수를 이용하여 수치 해석을 수행하였으며, KRISO의 장수조에서 실험을 수행하였다. 수치 해석과 실험 결과로부터 샘플링이 길어짐에 따라 의사 슬라이딩 모드 제어기는 연속계에 대한 슬라이딩 모드 제어기에서 발생하는 과도한 채터링 및 불안정성을 보이지 않았으며, 시스템의 안정성이 확보되고 불확실성에 대하여 강인한 제어 성능을 보였다. 또한, 본 논문에서는 수치 해석과 실험 결과를 근거로 의사 슬라이딩 모드 제어기의 설계를 위한 제어 변수의 선정 기준을 제시하였다.

• Proceedings of the IEEK Conference
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• 1999.06a
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• pp.805-808
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• 1999

In this paper, a chattering alleviation ISM speed controller for the sinusoidal type BIDC motor is designed. Dead Zone function is proposed to change the chattering occurring in the transient state form high frequency to low frequency and time-varying gains are applied for the control input to eliminate the steady state excessive chattering in the conventional ISM. The proposed Dead Zone function represents the sliding layer composed of two switching surfaces and if a state vector exists in this layer, the chattering don’t occur. Simulation and experimental results confirm the useful effects of the above algorithm.