• The Journal of the Korea institute of electronic communication sciences
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• v.13 no.1
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• pp.93-100
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• 2018

This study proposes a controller that compensates torque error for precise angular velocity tracking and a method to compensate the stability of controller in implementation. Also, it is proved that the designed controller can be asymptotically stable based on Lyapunov stability theory. The proposed controller is able to control the d-axis reference current to arbitrary values and easily achieve control performance with two gains. As a result of applying to IPMSM of about 750W class, the steady state error with reference speed 1200 [RPM] is within 0.1 [%]. And it can be seen that it is an asymptomatic stable controller overcoming disturbance within about 0.2 second in application of constant load of about 5 [Nm].

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.15 no.6
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• pp.71-77
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• 2015

In this paper, we propose a scheduling method for signal measurement and control algorithm execution in a multi-motor drive controller. The multi-motor controller which is used for vehicle control receives position/velocity command and performs position/velocity control and current control. Internal resource allocation and control algorithm execution timing are very important when one microcontroller is used for multi-motor drives. The control performance of the velocity control system is verified by varying ADC(Analog to Digital Converter) conversion timing and algorithm execution timing using real experiments.

• International Journal of Internet, Broadcasting and Communication
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• v.16 no.3
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• pp.146-157
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• 2024

Despite numerous air mattresses marketed to prevent Pressure Ulcers (PU), none have fully succeeded due to residual pressure surpassing critical levels. We introduces an innovative medical bed system aiming at complete PU prevention. This system employs a unique 4-bar link mechanism, moving keys up and down to manage body pressure. Each of the 17 keys integrates a sensor controller, reading pressure from 10 sensors. By regulating motor input, we maintain body pressure below critical levels. Keys are equipped with a servo drive and sensor controller, linked to the main controller via two CAN series. Using fuzzy or PI/IP controllers, we adjust keys to minimize total error, dispersing body pressure and ensuring comfort. In case of controller failure, keys alternate swiftly, preventing ulcer development. Through experimental tests under varied conditions, the fuzzy controller with tailored membership functions demonstrated swift performance. PI control showed rapid convergence, while IP control exhibited slower convergence and oscillations near zero error. Our specialized medical robot bed, incorporating 4-bar links and pressure sensors, underwent testing with three controllers-fuzzy, PI, and IP-showcasing their effectiveness in keeping body pressure below critical ulcer levels. Experimental results validate the proposed approach's efficacy, indicating potential for complete PU prevention.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.1
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• pp.99-106
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• 2017

Audible Pedestrian Signal(APS) is an additional equipment to provide information about pedestrian signals in non-visual formats such as audible tones and verbal messages. It can provide information to pedestrians about the location and directions of a crosswalk, and the traffic signal status. In general, a pedestrian who is visually impaired uses a 358.5MHz wireless remote controller to activate the APS and crosses at the crosswalk with the help of the APS. The existing APS can only receive an activation message from the remote controller. Therefore, the APS has an issue, especially at intersections, that all APSs within the communication range of the remote controller are activated simultaneously. It makes to confuse the visual impaired pedestrians. In this paper, we propose a BLE-enabled APS that can enable two-way communication via Bluetooth with a smartphone. The proposed system solves the problem and provides them with additional information, so that visually impaired pedestrians can cross at the crosswalk more conveniently.

• The Journal of the Korea institute of electronic communication sciences
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• v.14 no.4
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• pp.715-722
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• 2019

This paper introduces the implementation of an user-aware system using a visible light communication and its operations. The user-aware system using a visible light communication consists of the transmitter based on the Android system and the receiver based on an open-source controller. In the transmitter, user's personal information data is encoded and converted to visible light signals by the Android camera interface. In the receiver, the photodiode module receives the incoming visible light signals and converts to electrical signals and the open-source controller, that is arduino processes the received data. The processing module finds the start bit of 0111 to determine the user information data from the packet for the burst-mode communication. According to the experimental results, the proposed system successfully transmits and receives visible light data with the manchester encoding.

• The Journal of the Korea institute of electronic communication sciences
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• v.9 no.6
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• pp.681-687
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• 2014

Nuclear industries have faced unfavorable circumstances such as an obsolescence of the instrumentation and control system, and therefore nuclear society is striving to resolve this issue fundamentally. IEC and IAEA judge that FPGA technology is a good replacement for Programmable Logic Controller (PLC) of Nuclear Instrumentation and Control System. FPGAs are currently highlighted as an alternative means for obsolete control systems. Because the main function inside an FPGA is initially developed as software, good software quality can impact the reliability of an FPGA-based controller. Therefore, it is necessary to establish a software development aspect strategy that enhances the reliability of an FPGA-based controller. In terms of software development, HDL-Programmed Device (HPD) Development Life Cycle is applied into FPGA-based Controller. The burn-in test and environmental(temperature) test should be performed in order to apply into nuclear instrumentation and control system. Therefore it is ensured that the developed FPGA-based controller are normally operated for 352 hours and 92 hours in test chamber of Korea Institute of Machinery and Materials (KIMM).

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2005.05a
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• pp.1117-1123
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• 2005

This paper deals with a new automated guided vehicle (AGV) control system for distributed control. Proposed AGV control system adapts the multi-agent technology. The system is composed of two types of controller: routing and order. The order controller is in charge of assignment of orders to AGVs. Through the bidding-based negotiation with routing controllers, the order controller assigns a new order to the proper AGV. The order controller announces order information to the routing controllers. Then the routing controllers generate a routing schedule for the order and make a bid according to the routing schedule. If the routing schedule conflicts with other AGV's one, the routing controller makes an alternative through negotiation with other routing controllers. The order controller finally evaluates bids and selects one. Each controller consists of a set of agents: negotiation agent, decision making agent and communication agent. We focus on the agent architecture and negotiation-based AGV scheduling algorithm. Proposed system is validated through an exemplary scenario.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.3 no.2
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• pp.403-410
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• 1999

A conventional PID controller has poor performance when it applied to systems with unknown deadzones. To solve this problem, this paper proposes PID controller using two layered-fuzzy logic. The structure of controller is reconstructed with fuzzy compensator and fuzzy tuner on the conventional PID controller. Our proposed control scheme shows superior transient and steady-state performance compared to conventional PID controller. The scheme is robust to variations in deadzone nonlinearities as well as the steady-state gain of the plant. The performance of the developed controller is verified through simulation.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.57 no.1
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• pp.46-55
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• 2008

In this paper, we designed the bay control unit that is based on the microprocessors and integrates with the new technology of electrical, electronic, and mechanical fields. Nowadays the customers have required much more integrated multi-protection relay, monitoring, control devices and power management for better and easier maintenance, performance, electrical system analysis and communication according to new trend of switchboard This bay controller supplies those requirements of customers with easy handling and operation. This bay controller provides a graphic display with rear-lit liquid crystal LCD and push buttons as kinds of HMI(Human Machine Interface). This bay controller provides the parameter setting program, control setting program, various editors and fault recording and analysis program on Windows/95/98/NT/2000/XP for HMI. In addition, this bay controller can be set manually and this manual setting function helps user to interface easily.

• Proceedings of the KIEE Conference
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• 1996.07b
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• pp.1341-1343
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• 1996

This paper presents a design method for an on-line adaptive neural networks based intelligent controller. The proposed neural controller, assuming PID controller is initially presented, learns the equivalent behaviors of the existing PID controller initially and switches to take over the PID control system. Then, it executes on-line adaptation via evaluating its performance and minimizing user defined cost function constantly so that the optimal control can be achieved. The PID controller and the proposed neural controller are investigated and compared in computer simulation.