• Transactions of the Korean Society of Mechanical Engineers A
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• v.33 no.11
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• pp.1332-1340
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• 2009

The front end wheel loader is widely used for the loading of materials in mining and construction fields. It has repetitive digging, loading and dumping procedures. The bucket is subjected to large resistance force from the soil during scooping. We considered the soil reaction force characteristics from scooping procedure, the protection by overload and automatic scooping mode algorithm. The main topic of this paper is the analysis of the soil reaction force characteristics. The analysis of soil mechanics is carried out and the developed soil model is verified by experimental results from the simplified experimental equipment. A simplified model of the soil shape and bucket trajectory is used to determine the scooping direction based on an estimation of the resistance force applied on the bucket during the scooping motion. In the future, this model will be used for the generation of an appropriate path for the wheel loader automation.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.12 no.1
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• pp.1-20
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• 2018

Service composition in the Inter-Cloud raises new challenges that are caused by the different Quality of Service (QoS) requirements of the users, which are served by different geo-distributed Cloud providers. This paper aims to explore how to select and compose such services while considering how to reach high efficiency on cost and response time, low network latency, and high reliability across multiple Cloud providers. A new hybrid multi-objective evolutionary algorithm to perform the above task called LS-NSGA-II-DE is proposed, in which the differential evolution (DE) algorithm uses the adaptive mutation operator and crossover operator to replace the those of the Non-dominated Sorting Genetic Algorithm-II (NSGA-II) to get the better convergence and diversity. At the same time, a Local Search (LS) method is performed for the Non-dominated solution set F{1} in each generation to improve the distribution of the F{1}. The simulation results show that our proposed algorithm performs well in terms of the solution distribution and convergence, and in addition, the optimality ability and scalability are better compared with those of the other algorithms.

• Journal of Institute of Control, Robotics and Systems
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• v.4 no.1
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• pp.113-122
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• 1998

This paper presents an implementation method of Profibus interface software using FMS(Fieldbus Message Specification). The Profibus interface software is implemented on PC which is widely used as an industrial computer as well as a commercial embedded controller called IUC(Intelligent Universal Controller). In order to enable the Profibus interface software to handle many application tasks and communication services, two kinds of real-time/multi-tasking operating system, OS-9 and CTask, are utilized. We also develop an experimental model of Profibus-based automation system, and evaluate the performance of the Profibus network. Through experiments, the user layer level message latency is measured with respect to the change of message length, message generation interval and TRT(Target Rotation Time). The results of experiment are compared with those of a simulation model which comprises only the physical and data link layers of Profibus. The results of this study shows that the message latency in the user layer level occupies fairly a large part of the total message latency.

• Journal of the Korean Society for Precision Engineering
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• v.28 no.10
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• pp.1181-1188
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• 2011

A control system for stabilizing a small robot or inverted pendulum using twisted gyro wheel is proposed. Conventional stabilizer using inertial wheel employs action-reaction force/torque to control a pendulum, which can generate relatively small torque and short period of output. In this paper, a novel actuation method using twisted gyro torque in 3-dimentional space was proposed to stabilizing a pendulum by twisting the assembly including a rotating gyro wheel. In addition, two special control functions for this type of twisted gyro wheel were designed. One is the function of self-adjusting the mass center of the robot and the other is the torque reloading configuration for continuous torque generation. The proposed system was verified by experimental result and simulation. The designed twisted gyro wheel control system can be easily packed in a small size module and installed in a humanoid robot or inverted pendulum type mechanism.

• Journal of the Korea Safety Management & Science
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• v.22 no.1
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• pp.15-21
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• 2020

Industrial Motors diagnostic equipment is highly dependent on the automation system, so if there are defects in the automation equipment, it can only rely on the operator's intuitive judgment.To help with intuitive judgment, Park's Vactor Approach(PVA) represents the current signal as a pattern of circles, so it can tell if a fault occurs when the circle is distorted. However, the failure to judge the degree of distortion of the circle pattern is the basis of the fault, so it will face difficulties. In this paper, in order to compare the faults of PVA, the period of d-axis current of PVA pulsation was mastered, so that two phase differences occurred in the same signal source. Through experiments, it is confirmed that this is a 90 degree cross formation of PVA, which is convenient for judging from the vision that there is no fault, thus helping the operator to make intuitive judgment.

• Journal of Power Electronics
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• v.16 no.6
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• pp.2338-2349
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• 2016

This paper presents an impedance-matching-based control scheme for the harmonic resonance damping of multiple grid-connected-converters (GCCs) with LCL filters. As indicated in this paper, harmonic resonance occurs if a GCC possesses an output impedance that is not matched with the rest of the network in some specific frequency bands. It is also revealed that the resonance frequency is associated with the number of GCCs, the grid impedance and even the capacitive loads. By controlling the grid-side current instead of the converter-side current, the critical LCL filter is restricted as an internal component. Thus, the closed-loop output impedance of the GCC within the filter can be configured. The proposed scheme actively regulates the output impedance of the GCC to match the impedance of the external network, based on the detected resonance frequency. As a result, the resonance risk of multiple GCCs can be avoided, which is beneficial for the plug-and-play property of the GCCs in microgrids. Simulation and experimental results validate the effectiveness of the proposed method.

• Journal of Institute of Control, Robotics and Systems
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• v.12 no.11
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• pp.1144-1155
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• 2006

Digital communication networks have become a core technology in advanced building automation systems. BACnet(Building Automation and Control networks) is a standard data communication protocol designed specifically for building automation and control systems. BACnet adopts Master-Slave/Token-Passing(MS/TP) protocol as one of its field level networks. In this study, we introduce a method of implementing a bandwidth allocation scheme in the MS/TP protocol. The bandwidth allocation scheme improves the capability of real-time communication of the original MS/TP protocol. The bandwidth allocation scheme introduced in this paper can be easily implemented in the existing MS/TP protocol with a slight modification. In this study, we actually developed the hardware and firmware of the modified MS/TP communication module in which the bandwidth allocation scheme is implemented. Using the modified MS/TP communication module, we developed an experimental model in order to examine the validity of the bandwidth allocation scheme in the MS/TP protocol. Experimental results show that the modified MS/TP protocol satisfies the requirements of real time communication for periodic and urgent messages of BACnet communication services.

• Journal of Electrical Engineering and Technology
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• v.13 no.1
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• pp.352-361
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• 2018

This paper proposes a sensing system of the Halbach array permanent magnet spherical motor(PMSM). The rotor position can be obtained by solving three rotation angles, which revolves around 3 reference axes of the stator. With the development of 3-D hall sensor, the position identification problem of the Halbach array PMSM based on rotor magnetic field is studied in this paper. A nonlinear and serious coupling relationship between the rotation angles and the measured magnetic flux density is established on the basis of the rotation transformation theory and the magnetic field model. In order to get rid of the influence on position detection caused by the harmonics of rotor magnetic field and the stator coil magnetic field, a sensor location combination scheme is proposed. In order to solve the nonlinear equation fast and accurately, a new position solution algorithm which combines the merits of gradient projection and particle swarm optimization(PSO) is presented. Then the rotation angles are obtained and the rotor position is identified. The validity of the sensing system is verified through the simulation.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.8 no.2
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• pp.79-85
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• 2015

Home automation technology combines various devices in home organically with each other to ensure the convenience and improved safety of the home life refers to a technique for improving the human living. Because of the technology needed to make this house before you can act as awareness of your thoughts. In this paper, we implement the system model, such as data collection using a sensor network, and take advantage of the idea that the data itself to the home, and an introduction to the method.

• Journal of Power Electronics
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• v.10 no.6
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• pp.673-679
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• 2010

Input-series-output-parallel (ISOP) connected DC-DC converters enable low voltage rating switches to be used in high voltage input applications. In this paper, a DSP is adopted to generate digital phase-shifted PWM signals and to fulfill the closed-loop control function for ISOP connected two full-bridge DC-DC converters. Moreover, a stable output current sharing control strategy is proposed for the system, with which equal sharing of the input voltage and the load current can be achieved without any input voltage control loops. Based on small signal analysis with the state space average method, a loop gain design with the proposed scheme is made. Compared with the conventional IVS scheme, the proposed strategy leads to simplification of the output voltage regulator design and better static and dynamic responses. The effectiveness of the proposed control strategy is verified by the simulation and experimental results of an ISOP system made up of two full-bridge DC-DC converters.