• Journal of Drive and Control
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• v.21 no.2
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• pp.65-71
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• 2024

In this study, we suggested a key-point detection method for robot harvesting of oriental melon. Our suggested method could be used to detect the detachment part and major composition of oriental melon. We defined four points (harvesting point, calyx, center, bottom) based on tomato with characteristics similar to those of oriental melon. The evaluation of estimated key-points was conducted by pixel error and PDK (percentage of detected key-point) index. Results showed that the average pixel error was 18.26 ± 16.62 for the x coordinate and 17.74 ± 18.07 for the y coordinate. Considering the resolution of raw images, these pixel errors were not expected to have a serious impact. The PDK score was found to be 89.5% PDK@0.5 on average. It was possible to estimate oriental melon specific key-point. As a result of this research, we believe that the proposed method can contribute to the application of harvesting robot system.

• Journal of Drive and Control
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• v.21 no.2
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• pp.8-14
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• 2024

This paper investigates the jetting characteristics of an aerosol jet printing (AJP) process as a function of design and operating conditions. The governing equations of the AJP system are derived for experimentation and analysis. To understand the characteristics of the AJP system, this thesis analyzes the jetting characteristics as a function of the flow rate of the carrier gas and the sheath gas, and the variation of the linewidth with the nozzle exit size based on particle tracking. This thesis focuses on computational fluid dynamics (CFD), which is a computer simulation. The particle tracking results obtained by CFD were analyzed using MATLAB. CFD analytical models can be analyzed in environments with different conditions and consider more specific situations than mathematical computational models. The validity of the CFD analysis is shown by comparing the experimental results with the CFD analysis.

• Journal of Drive and Control
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• v.21 no.2
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• pp.1-7
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• 2024

This paper proposes a novel cooling system for hydrogen fuel cell cooling systems by integrating heat pump technology to enhance operational efficiency. The study analyzed the cooling efficiency of the fuel cell cooling system. With the increasing focus on eco-friendly vehicle technologies to address environmental concerns and global warming, the transportation sector, a major contributor to greenhouse gas emissions, needs technological enhancements for better efficiency. The proposed cooling system was modeled through 1-D simulations. The analysis results of parameters such as thermal balance, temperature, and pressure of each component confirmed the stable operation of the system. By examining variations in the cooling system's flow rate, compressor RPM, and the Coefficient of Performance (COP) based on different refrigerants, initial research was conducted to derive optimal operating conditions and parameter values.

• Journal of Drive and Control
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• v.21 no.2
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• pp.15-22
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• 2024

The objective of this study was to examine whether a gerotor pump used in a transmission could be converted into an electric vehicle thermal management system pump using a virtual design environment. To achieve this objective, we first built an environment that could analyze the performance of a gerotor pump in heat transfer fluid. Flow rate, pressure, and volumetric efficiency were then analyzed when using heat transfer fluid in a gerotor pump. Finally, how large the displacement volume of the pump should be designed when using a heat transfer fluid other than oil was determined. Based on results of this study, it is expected that gerotor pumps will be applied to new business fields such as electric vehicle cooling systems.

• Journal of Drive and Control
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• v.21 no.3
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• pp.9-19
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• 2024

Many modern hydraulic excavators now use EPPRVs (Electronic Proportional Pressure Reducing Valves) in their pilot systems to control the spool displacement of the main hydraulic system. However, the performance of these systems is often limited by factors such as magnetic hysteresis, mechanical wear, and transient responses influenced by operating conditions and component installation. This paper presents a pressure feedback controller for excavator pilot systems that utilize EPPRVs. This controller significantly reduces steady-state pressure control errors and mitigates the hysteresis effects commonly seen in traditional open-loop systems. To achieve this, we integrated EPPRVs with the main hydraulic valve and injected a chirp signal into the solenoid current. By doing so, we were able to measure the frequency response of the pilot system across different operating pressures and estimate the system dynamics model. Using these models, we designed a set of PI pressure feedback controllers that are guaranteed to be stable. These controllers were then integrated with a gain scheduler based on a lookup table. Experimental results demonstrate that when the developed pressure feedback controller is incorporated into the conventional open-loop controller, it effectively reduces steady-state pressure control errors and mitigates hysteresis.

• Journal of Drive and Control
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• v.21 no.3
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• pp.1-8
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• 2024

Electric cart, one of the many devices created to aid golfers, combines software and wireless technology with over 200 different parts and computers. It is designed to be controlled remotely and can be started or stopped using a remote control while on the golf course. However, one recurring issue is the frequent derailment of the electric cart during operation. This problem not only hampers game performance but also causes delays as drivers lose focus. The objective of this study is to enhance the driving system of autonomous electric carts, which are controlled by the driver's signals, in order to address the issue of derailments. These autonomous carts follow a line tracer on the course. By examining the evolution of golf carts and the safety enhancements implemented in current models, we propose to supplement the autonomous driving system to increase safety and improve the performance of these electric carts.

• Journal of Drive and Control
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• v.21 no.3
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• pp.28-35
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• 2024

This study compared performances of PID (Proportional Integral Derivative), SMC (Sliding Mode Control), and MPC (Model Predictive Control) strategies applied to a 2DOF (Degree Of Freedom) drone tracking robot. The developed 2DOF robot utilized a depth camera with an IMU (Inertial Measurement Unit), laser pointers, and servo motors to rapidly detect and track objects. Image processing was conducted using the YOLO deep learning model. Through this setup, controllers were attached to the robot to track random drone movements, comparing performances in terms of accuracy and energy consumption. This study revealed that while SMC demonstrated precise tracking without deviating from the path, both PID and MPC controllers showed deviations. Performance-wise, SMC is superior. However, considering economic aspects, PID is more advantageous due to its lower power consumption and relatively minor tracking errors.

• Journal of Drive and Control
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• v.21 no.3
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• pp.36-45
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• 2024

Collaborative robots, designed for direct interaction with humans have limited adaptability to environmental changes. This study addresses this limitation by implementing a barista robot system using AI technology. To overcome limitations of traditional collaborative robots, a model that applies a real-time object detection algorithm to a 6-degree-of-freedom robot arm to recognize and control the position of random cups is proposed. A coffee ordering application is developed, allowing users to place orders through the app, which the robot arm then automatically prepares. The system is connected to ROS via TCP/IP socket communication, performing various tasks through state transitions and gripper control. Experimental results confirmed that the barista robot could autonomously handle processes of ordering, preparing, and serving coffee.

• Proceedings of the Korea Water Resources Association Conference
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• 2005.05b
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• pp.1148-1153
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• 2005

하수관거는 국민의 정맥이라고 할 수 있을 정도로 도시의 환경관리와 치수, 쾌적한 환경조성에 있어서 매우 중요한 시설이며 그 규모가 광범위하고 복잡한 네트워크로 구성되어 있다. 이러한 하수관망을 통해 이송되는 물은 지저분하고 냄새가 심하기 때문에 지하에 관의 형태로 대부분 시공되어 왔으며, 상수관망처럼 압력관이 아니라 대부분 중력에 의한 이송방식을 채택하고 있어 문제 발생 시 원인파악과 대처를 힘들게 하는 요인을 가지고 있다. 특히 하수관거의 관리 소홀은 곧바로 토양오염과 인근 환경오염으로 직결되며 장기적으로는 상수를 오염시키는 요인으로 작용하므로 체계적인 방법과 장기적인 안목을 가지고 명확한 분석을 시행할 수 있는 시스템을 가지고 최적으로 유지관리 되어야 한다. 최근 들어 이러한 하수도 시설을 효율적으로 관리 및 개선하기 위해 대도시를 중심으로 근거 조사와 정비 사업이 활발히 시행되고 있다. 그러나, 사업효과를 검증하거나 관로의 유지관리를 위하여 국내 실정에 맞지 않는 외국하수관망 흐름 해석 프로그램을 그대로 사용하고 있고 정확한 해석이 이루어지지 않고 있어 효율적인 유지관리가 어렵다. 이와 같은 문제점을 해결하기 위하여 하수관망해석이나 하수관망 정비시 필요한 불명수산정이 가능하고 국내실정에 맞는 프로그램 개발이 시급한 실정이며, 아울러 프로그램을 효율적 운영하고 관리하는 제어관리 기술을 개발, 진행하고 있다. 본 논문에서는 개발된 프로그램의 부정류 해석 기능을 활용하여 대상구역의 해석을 실시하여 기존분석방법의 I/I결과와 비교하였으며 최적관리를 위한 방안을 제시하였다.준편차가 증가하고 있음을 알 수 있다. 본 연구에서는 상용 CFD모형인 FLOW-3D를 계획 중인 하수처리장의 침전지 유입부 설계에 적용하였으며 저류벽의 위치와 폭, 유공정류벽의 유공율에 따른 유입하수의 분배효과를 분석하였다. 실험을 수행하여 보다 정밀한 공식으로 개선할 수 있었다.$10,924m^3/s$ 및 $10,075m^3/s$로서 실험 I의 $2,757m^3/s$에 비해 통수능이 많이 개선되었음을 알 수 있다.함을 알 수 있다. 상수관로 설계 기준에서는 관로내 수압을 $1.5\~4.0kg/cm^2$으로 나타내고 있는데 $6kg/cm^2$보다 과수압을 나타내는 경우가 $100\%$로 밸브를 개방하였을 때보다 $60\%,\;80\%$ 개방하였을 때가 더 빈번히 발생하고 있으므로 대상지역의 밸브 개폐는 $100\%$ 개방하는 것이 선계기준에 적합한 것으로 나타났다. 밸브 개폐에 따른 수압 변화를 모의한 결과 밸브 개폐도를 적절히 유지하여 필요수량의 확보 및 누수방지대책에 활용할 수 있을 것으로 판단된다.8R(mm)(r^2=0.84)$로 지수적으로 증가하는 경향을 나타내었다. 유거수량은 토성별로 양토를 1.0으로 기준할 때 사양토가 0.86으로 가장 작았고, 식양토 1.09, 식토 1.15로 평가되어 침투수에 비해 토성별 차이가 크게 나타났다. 이는 토성이 세립질일 수록 유거수의 저항이 작기 때문으로 생각된다. 경사에 따라서는

• Journal of Drive and Control
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• v.17 no.2
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• pp.1-8
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• 2020

Recently, industrial systems are becoming quicker and lighter to enable the reduction of energy consumption and increase productivity. So the latest systems are more flexible and rapid than the previous systems. But, with this improvement, another problem has emerged, such as the increase in residual vibration when a system is started or stopped. The input shaper is a command generation method that can remove residual vibration. It can provide a solution to the problem of residual vibration in industrial systems. However, it is difficult to generate the input shaper in high order systems, such as a typical industrial system because the input shaper is induced from the system's vibration characteristics. This study focused on the extra insensitivity shaper that can compensate for the system's modeling error such as input dynamics, and the high order's system affection. A genetic algorithm was deployed to adjust a vibration limitation for the extra insensitivity of the input shaper. A plant is a low damping system that includes one zero and a pole. The fitness functions are an error signal of the system's response with normalized frequency variations. Verification of the suggested system is satisfied by comparison between the zero vibration derivative input shaper's response and the suggested one.