• Proceedings of the KIEE Conference
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• 1996.07b
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• pp.1377-1379
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• 1996

In this paper, each parameter was identified by the gradient descent method to overcome difficulty deciding fuzzy rules of FLC for the unknown process and the type of membership Junctions. Usually PID or optimal control theories have been mostly usee in control field so far. However, optimal control requires much time for calculation because of adaptation for disturbance and nonlinearity. And intricate technique such as MRAS which can be realized only by an expert are limited to be used in the systems requiring rapid and precise response because of comparatively longer calculating time and complicateness. Gradient descent method is a method to find Z minimizing a function about a certain vector Z. And required output of FLC is gained using gradient approaching method in order to adapt control rule parameters of FLC. Simulation proved validation of this algorithm.

• Proceedings of the Korea Information Processing Society Conference
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• 2018.10a
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• pp.434-437
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• 2018

본 논문에서는 ROS (Robot Operating System)에 대해서 소개하고 ROS를 이용해 드론의 제어기와 필터를 구현해본다. 드론이 강인한 성능을 보이기 위해서는 기체의 상태에 대한 더 정확한 추정이 필요하다. 드론이 기체좌표계로 출력하는 각 축(x축, y축, z축)에 대한 선속도, 선가속도를 더 정확히 추정하기 위해 칼만 필터를 설계하며 칼만 필터를 통과한 상태 변수를 제어 입력으로 하는 PID(Proportional Integral Derivative) 제어기를 설계한다. 실험적인 부분에서는 제어기와 자율 주행 알고리즘을 접목시켜 드론이 자신의 상태를 추정하고 알고리즘을 순차적으로 진행하는 과정을 살펴본다. 마지막으로 알고리즘을 통해 드론의 임무 수행 여부를 살펴보고 정밀한 제어를 위한 추가적인 제어기 설계 방법과 연구 방향을 제시하고자 한다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.08a
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• pp.41-46
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• 2002

본 논문은 냉, 난방 디지털 온도 조절계(SPC 50)의 Etl의 편차 정 동작에 관한 구현장치 제작과 비례 미.적분기가 At 및 비 At기능에서 설정온도를 $100^{\circ}C$를 유지하는데 기인된 전압전류 및 전력데이터 획득의 요인과 비례미적분 정수 및 노 개선점을 연구하였다. 설정온도를 유지하는 온도변화는 At기능에서 $96.7^{\circ}C\sim102^{\circ}C$ 이며, 비At 기능에서는 $97.6^{\circ}C\sim100.2^{\circ}C$이었다. 온도유지 전압변동은 At기능에서 2V~217V이며, 비 At기능에서 20V~217V 이었다. At와 비 At 기능에서 설정온도 $100^{\circ}C$을 유지하는데 온도를 냉각시키는 환풍기가 온. 오프 되는 시간차는 20초 정도 발생하였다. 온도차 및 전압차는 두 기능간에 비례 미. 적분값 설정이 자동 및 수동이냐에 따라서 차이를 보여주었다. 두 기능에서 설정된 온도값 유지에 따른 전압전류의 승압과 하강의 변동된 변환 데이터는 설정된 온도가 성취되어지는 시간차 및 설정값 유지의 특성을 요인으로 한 PID값과 노의 개선점에 길잡이가 된다.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.25 no.10
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• pp.707-713
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• 2015

This paper proposes experimental results for control performance deterioration of a piezoelectric actuator under high temperature conditions due to external heat environment. In this work, a heat environment from 30 ℃ to 190 ℃ is established by a heat chamber which is capable of high temperature of heat environment. Inside the heat chamber, an experimental apparatus consisting of the stack type of piezoelectric actuator, laser sensor, gap sensor and temperature sensor is established. After evaluating temperature dependent blocking force, displacement and time response of a piezoelectric actuator inside the heat chamber, tracking control performances are evaluated under various temperature conditions via proportional-integral-derivative(PID) feedback controller. The desired position trajectory has a sinusoidal wave form with a fixed frequency. Control performances are experimentally evaluated at both room temperature and high temperature and presented in time domain.

• Journal of Drive and Control
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• v.11 no.3
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• pp.31-40
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• 2014

This paper proposes a multi absorbing wave energy converter design, in which a hydrostatic transmission is used to transfer wave energy to electric energy. The most important feature of this system is its combination of the pressure coupling principle with the use of a hydraulic accumulator to eliminate the effects of wave power fluctuation; this maintains a constant speed of the hydraulic motor. Tilt motion of a floating buoy was employed as the power take-off mechanism. Furthermore, a PID controller was designed to carry out the speed control of the hydraulic motor. The design offers some advantages such as extending the life of the hydraulic components, increasing the amount of energy harvested, and stabilizing the output speed.

• Journal of Auto-vehicle Safety Association
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• v.13 no.4
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• pp.129-143
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• 2021

This paper proposes actuator fault detection and adaptive fault-tolerant control algorithms using performance index and human-like learning for longitudinal autonomous vehicles. Conventional longitudinal controller for autonomous driving consists of supervisory, upper level and lower level controllers. In this paper, feedback control law and PID control algorithm have been used for upper level and lower level controllers, respectively. For actuator fault-tolerant control, adaptive rule has been designed using the gradient descent method with estimated coefficients. In order to adjust the control parameter used for determination of adaptation gain, human-like learning algorithm has been designed based on perceptron learning method using control errors and control parameter. It is designed that the learning algorithm determines current control parameter by saving it in memory and updating based on the cost function-based gradient descent method. Based on the updated control parameter, the longitudinal acceleration has been computed adaptively using feedback law for actuator fault-tolerant control. The finite window-based performance index has been designed for detection and evaluation of actuator performance degradation using control error.

• Nuclear Engineering and Technology
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• v.53 no.2
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• pp.455-465
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• 2021

The Molten Salt Reactor (MSR), one of the six advanced reactor types of the 4th generation nuclear energy systems, has many impressive features including economic advantages, inherent safety and nuclear non-proliferation. This paper introduces a system analysis code named TREND, which is developed and used for the steady and transient simulation of MSRs. The TREND code calculates the distributions of pressure, velocity and temperature of single-phase flows by solving the conservation equations of mass, momentum and energy, along with a fluid state equation. Heat structures coupled with the fluid dynamics model is sufficient to meet the demands of modeling MSR system-level thermal-hydraulics. The core power is based on the point reactor neutron kinetics model calculated by the typical Runge-Kutta method. An incremental PID controller is inserted to adjust the operation behaviors. The verification and validation of the TREND code have been carried out in two aspects: detailed code-to-code comparison with established thermal-hydraulic system codes such as RELAP5, and validation with the experimental data from MSRE and the CIET facility (the University of California, Berkeley's Compact Integral Effects Test facility).The results indicate that TREND can be used in analyzing the transient behaviors of MSRs and will be improved by validating with more experimental results with the support of SINAP.

• The Journal of Korea Robotics Society
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• v.17 no.1
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• pp.48-57
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• 2022

In this paper, we propose a legged landing platform for the quadcopter taking off and landing in the ship environment. In the ship environment with waves and winds, the aircraft has risks being overturned by contact impact and excessive inclination during landing on the ship. This landing platform has four landing legs under the quadcopter for balancing and shock relief. In order to make the quadcopter balanced on ships, the position of each end effector was controlled by PID control. And shocks have mainly happened when quadcopter contacts the ship's surface as well as legs move fast. Hence, impedance control was used to cope with the shocks. The performance of the landing platform was demonstrated by a simulation and a prototype in three sea states based on a specific size of a ship. During landing and tracking the slope of the ship's surface, oscillations of rotation and translation from the shock were mitigated by the controller. As a result, it was verified that transient response and stability got better by adding impedance control in simulation models and prototype experiments.

• Journal of Drive and Control
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• v.19 no.2
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• pp.1-10
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• 2022

Field robots operate in various areas, including construction, agriculture, forestry and manufacturing. Typical tasks of field robots used in various areas include excavation, flattening, and demolition. Such tasks are often accomplished in narrow alleys or indoors. In the case of field robots, there is a limit to working in a small space. Thus, to compensate for these shortcomings, many field robots equipped with Tiltrotators have recently been observed. The advantages of Tiltrotator are improved task efficiency and reduced operating time by reducing unnecessary behavior. We need simulation models that can improve the ability of new people to work and simulate tasks in advance. Thus, in this paper, we developed a simscape-based simulation model and modeling of 6DOF systems for field robots equipped with Tiltrotator. Dynamic modeling of field robot 3D models using Simcape multibody and hydraulic systems of field robots using Simcape Hydraulics were modeled. We applied a PID controller to create a control system that operates along the input angle. Simulation results show that errors occur when comparing input and output angles, but overall, they move along input angles.

• The Journal of Korea Robotics Society
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• v.19 no.2
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• pp.149-158
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• 2024

This paper presents a robust autonomous navigation and reconnaissance system for tracked robots, designed to handle complex multi-floor indoor environments with stairs. We introduce a localization algorithm that adjusts scan matching parameters to robustly estimate positions and create maps in environments with scarce features, such as narrow rooms and staircases. Our system also features a path planning algorithm that calculates distance costs from surrounding obstacles, integrated with a specialized PID controller tuned to the robot's differential kinematics for collision-free navigation in confined spaces. The perception module leverages multi-image fusion and camera-LiDAR fusion to accurately detect and map the 3D positions of objects around the robot in real time. Through practical tests in real settings, we have verified that our system performs reliably. Based on this reliability, we expect that our research team's autonomous reconnaissance system will be practically utilized in actual disaster situations and environments that are difficult for humans to access, thereby making a significant contribution.