• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2004년도 Asia Navigation Conference
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• pp.45-53
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• 2004

In this paper, an INS compensation algorithm for auto sailing system is proposed, where low cost IMU (Inertial Measurement Unit) is used for measuring the accelerometer data. First, we denote the basic INS algorithm with IMU and show that how to compensate the error of position by using low cost IMU. Second, in considering the ship's characteristic and ocean environments, we consider with a factor as a periodic external disturbance which effects to the exact position. To develop the compensation algorithm, we use a repetitive method to reduce the external environment changes. Lastly, we verify the proposed algorithm by using experiments results.

• 대한기계학회논문집A
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• 제40권1호
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• pp.1-8
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• 2016

본 논문에서는 기존의 관성안정화 플랫폼에서 보편적으로 사용됐던 PID 제어에 외란관측기를 적용하는 알고리즘 제안한다. 외란관측기 알고리즘을 적용하기 위하여 직접구동 모터로 구동되는 안정화 플랫폼 축의 관성모멘트와 축 마찰 특성을 실험적으로 구하고, 시뮬레이션과 실험결과를 비교하여 정확도를 검증하였다. 또한 차수와 상대차수가 다른 여러 가지 Q-filter 적용실험을 통하여 필터 특성에 따른 시스템의 안정성을 확인하였다. 본 논문에서 제안한 알고리즘은 6 자유도 시뮬레이터를 이용하여 차량 모션 인가실험을 통해 이중 PID 제어 루프의 결과와 비교/검증하였다.

• 전자공학회논문지
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• 제52권5호
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• pp.190-196
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• 2015

본 논문은 항법장치 위치보정을 위해 칼만필터를 적용한 GPS/INS융합의 다중보정방법을 제안한다. 연구에서는 관성항법장치를 구현하기 위해 9축 항법장치로 보정알고리즘을 적용하여 위치오차를 감소시킨 방법을 적용했다. 일반적으로 GPS/INS는 위치정보를 얻어낼 수 있지만 위치정보를 구하는 과정에서 오차 또한 더불어 커지게 되기에 이를 보정하기 위한 강인한 오차 보정 알고리즘이 필요하다. 본 논문에서는 9축 관성센서(mpu-9150)의 외란에 대한 강인성 향상을 위해 가속도계 보정 알고리즘을 사용하여 tilt보정을 수행했으며, 제어 대상체의 정확한 방위를 파악할 수 있도록 Yaw각 재정의 알고리즘을 적용하였다. 최종적으로 GPS/INS와 칼만 필터를 함께 결합한 통합시스템을 구현하였다.

• 한국항공우주학회지
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• 제43권8호
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• pp.757-764
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• 2015

본 논문에서는 소형 지구관측 위성의 광학카메라에 들어가는 미소진동을 보상하기 위한 초점면부 보정장치 시스템의 실험적 모델링을 수행하였다. 미소진동 외란을 보상하는 초점면부 보정장치의 구동기로 PZT 압전작동기를 적용하였다. 압전작동기는 히스테리시스 고유 특성을 갖게 되므로 보정장치 시스템의 정확한 수학적 모델링을 얻는데 어려움이 있다. 따라서 본 연구에서는 보정장치 시스템을 2차 선형시스템으로 가정하고 MATLAB의 시스템 식별 툴박스(System Identification Toolbox)를 이용하여 실험적으로 모델링을 수행하였다. 외란의 주파수 범위인 0~50Hz에서 응답 오차 10%를 만족하기 위해 단일 선형 모델로는 불가능하며 총 4개의 선형 모델이 필요하다. 각각의 모델은 0~50Hz 입력범위를 4개의 구간으로 나눈 영역에서 실제 동역학을 잘 표현 하고 있다. 미소진동 외란의 보상은 입력주파수에 따라 모델 스위칭 기법을 적용한 초점면부 보정장치 제어를 통해 이루어진다.

• 한국정밀공학회지
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• 제33권10호
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• pp.837-843
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• 2016

This paper presents a position control strategy for a pump-controlled electro-hydrostatic actuator (EHA) using feedforward control with disturbance compensation. As the disturbance observer is used to estimate nonlinear dynamics of EHA, which has valve-opening conditionals, as well as external disturbances, an additional feedforward control is adopted to achieve rapid response. The effectiveness of the proposed control strategy is verified through experiment using an EHA test bench. The proposed controller shows better tracking performance compared with a conventional PID controller.

• 전력전자학회:학술대회논문집
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• 전력전자학회 1998년도 Proceedings ICPE 98 1998 International Conference on Power Electronics
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• pp.830-835
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• 1998

This paper describes a new digital control method of 3-phase PWM inverter with LC filter for uninterruptible power supply(UPS). The overall control system is based on the dead beat control, which has the minor loop of current control within the voltage control major loop. In this paper, the full-order disturbance observer is proposed to compensate the disturbances generated due to a sudden change of load currents. The proposed disturbance observer is composed of dead beat observer which estimates state values within a finite time, and cancels the disturbances by adding feedforward compensation loop in the control system. In addition, on order to remove a defect of oscillation generated in output of conventional dead beat controller, a modified dead beat algorithm is proposed in this paper.

• 전기학회논문지
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• 제57권7호
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• pp.1247-1253
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• 2008

A design method of a T-S fuzzy model based reduced order nonlinear unknown input observer(NUIO) is presented. The fuzzy NUIO is designed based on the parallel distributed compensation(PDC) concept. It consists of a number of the linear UIOs, each of which is designed for each local linear model in the T-S fuzzy model of a class of nonlinear systems. The fuzzy NUIO provides not only the state estimates insensitive to the unknown inputs, for example, disturbances and faults etc., but also the estimates of the unknown inputs. Therefore, It can be employed in the state feedback control and disturbance rejection control of a class of nonlinear systems with unknown disturbances. It also applied to the robust residual generation for the fault detection and isolation systems and to the design of fault tolerant control systems. As an example, the NUIO is applied to an inverted pendulum system to show the state and disturbance estimation performance and to illustrate the fuzzy reduced order NUIO design method.

• 대한전기학회논문지:시스템및제어부문D
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• 제49권9호
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• pp.526-537
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• 2000

This paper deals with a sliding mode controller with integral compensation in a magnetic suspension system The control scheme comprises an integral controller which is designed for achieving zero steady-steate error under step disturbance input and a sliding mode controller which is designed for enhancing robustness under plant parametric variations. A procedure is developed for determining the coefficients of the switching plane and integral control gain such that the overall closed-loop system has stable eigenvalues. A proper continuous design signal is introduced to overcome the chattering problem. The performance of a magnetically suspended balance beam using the proposed integral sliding mode controller is illustrated. Simulation and experimental results also show that the proposed method is effective under the external step disturbance and input channel parametric variations.

• 한국우주과학회:학술대회논문집(한국우주과학회보)
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• 한국우주과학회 2004년도 한국우주과학회보 제13권2호
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• pp.103-103
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• 2004

• Ocean Systems Engineering
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• 제10권4호
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• pp.373-397
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• 2020

Heave compensation is a vital part of various marine and offshore operations. It is used in various applications, including the transfer of cargo between two vessels in the open ocean, installation of topsides of an offshore structure, offshore drilling and for surveillance, reconnaissance and monitoring. These applications typically involve a load suspended from a hydraulically powered winch that is connected to a vessel that is undergoing dynamic motion in the ocean environment. The goal in these applications is to design a winch controller to keep the load at a regulated height by rejecting the net heave motion of the winch arising from ship motions at sea. In this study, we analyze and compare the performance of various control algorithms in stabilizing a suspended load while the vessel is subjected to changing sea conditions. The KCS container ship is chosen as the vessel undergoing dynamic motion in the ocean. The negative of the net heave motion at the winch is provided as a reference signal to track. Various control strategies like Proportional-Derivative (PD) Control, Model Predictive Control (MPC), Linear Quadratic Integral Control (LQI), and Sliding Mode Control (SMC) are implemented and tuned for effective heave compensation. The performance of the controllers is compared with respect to heave compensation, disturbance rejection and noise attenuation.