• Journal of Power Electronics
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• 제17권6호
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• pp.1650-1657
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• 2017

In this study, the distributed secondary voltage control of islanded microgrids with multi-agent consensus algorithm is investigated. As an alternative to a time-triggered approach, an event-triggered scheme is proposed to reduce the communication load among inverter-based distributed generators (DGs). The proposed aperiodic control scheme reduced unnecessary utilization of limited network bandwidth without degrading control performance. By properly establishing a distributed triggering condition in DG local controller, each inverter is only required to send voltage information when its own event occurs. The compensation of voltage amplitude deviation can be realized, and redundant data exchange related to fixed high sampling rate can be avoided. Therefore, an efficient use of communication infrastructure can be realized, particularly when the system is operating in steady state. The effectiveness of the proposed scheme is verified by simulations on a microgrid test system.

• 한국정밀공학회지
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• 제13권9호
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• pp.94-103
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• 1996

This paper is concerned with the theroretical and experimental study on the force control of a miniature robotic finger that grasps an object at three other positions with the fingertip. The artificial finger is uniform flexible cantilever beam equipped with a distributed set of compact grasping force secnsors. Control action is applied by a qiexoceramic bimorph strip placed at the base of the finger. The mathematical model of the assembled electro-mechanical system is developed. The distributed sensors are described by a set of concentrated mass-spring system. The formulated equations of motion are then applied to a control problem which the finger is commanded to grasp an object The PID-controller is introduced to drive the finger. The usefulness of the proposed control technique is verified by simulation and experiment.

• Transactions on Control, Automation and Systems Engineering
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• 제3권3호
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• pp.181-189
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• 2001

The software components of embedded control systems get extremely complex as they are designed into distributed systems get extremely complex as they are designed into distributed systems consisting of a large number of inexpensive microcontrollers interconnected by low-bandwidth real-time networks such as the controller area network (CAN). While recently emerging middleware technologies such as CORBA and DCOM address the complexity of distributed programming, they cannot be directly applied to distributed control system design due to their excessive resource demand and inadequate communication models. In this paper, we propose a CORBA-based middleware design for CAN-based distributed embedded control systems. Our design goal is to minimize its resource need and make it support group communication without losing the IDL (interface definition language) level compliance to the OMG standards. To achieve this, we develop a transport protocol on the CAN and a group communication scheme based on the well-known publisher/subscriber model. The protocol effectively realizes subject-based addressing and supports anonymous publisher/subscriber communication. We also customize the method invocation and message passing protocol, referred to as the general inter-ORB protocol (GIOP), of CORBA so that CORBA method invocations are efficiently serviced on a low-bandwidth network such as the CAN. This customization includes packed data encoding and variable-length integer encoding for compact representation of IDL data types. We have implemented our CORBA-based middleware on the mArx real-time operating system we have developed at Seoul National University. Our experiments clearly demonstrate that it is feasible to use CORBA in developing distributed embedded control systems possessing severe resource limitations. Our design clearly demonstrates that it is feasible to use a CORBA-based middleware in developing distributed embedded systems on real-time networks possessing severe resource limitations.

• 한국지능시스템학회논문지
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• 제16권4호
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• pp.485-492
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• 2006

본 논문은 휴머노이드 로봇 ISHURO의 분산 제어를 위한 네트웍 구현에 대해 다루고 있다. 일반적으로 휴머노이드형 로봇은 기구학적으로 유연한 동작을 위해 다수의 자유도가 필요하다. 이를 구현하기 위해서는 중앙에서 일괄적으로 처리 하는 것 보다 간결 하면서도 유연성을 줄 수 있는 분산 처리 방법이 선호되고 있다. 분산 처리를 위한 제어기를 구성할 때는 로봇의 모터를 독립적으로 제어하기 위한 제어기가 별도로 필요하며 모듈 간에는 정해진 시간 내에 데이터를 교환할 수 있는 통신 기법이 필요하다. ISHURO의 각 관절은 자체 내에 독립된 DSP를 내장하고 있으며 CAN 네트웍을 이용하여 모듈간의 통신을 하여 구동기를 재어하거나 센서의 값을 모니터링 할 수 있게 되어 있다. 본 논문에서는 이를 위한 통신 구조를 제안하고 필요한 전송 메시지를 정의하고, 전송시간을 분석하여 로봇 분산 제어기 구조에 적절한 전송 프로토콜을 제시하였다. 모든 과정은 Matlab을 이용하여 컴퓨터모의실험을 수행하였고 실제 휴머노이드 로봇에 적용하여 보행실험을 통해 검증 하였다.

• 제어로봇시스템학회논문지
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• 제6권10호
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• pp.911-917
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• 2000

As many sensors and actuators are used in various automated systems, the application of network to real-time distributed control system is gaining acceptance in many industries. In order to take advantages of networking, however, the network should be carefully designed to satisfy real-time distributed control. This paper presents an implementation method of closed-loop control using Profibus-FMS. In order to implement a closed-loop control system, we used industrial computers with Profibus-FMS network cards and a DC servo motor. Through various experiments, the step response of the control system with network was compared with the reference response without network.

• 대한임베디드공학회논문지
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• 제17권2호
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• pp.115-121
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• 2022

This paper proposes a distributed model predictive formation control algorithm for a group of unmanned ground vehicles (UGVs) with guaranteeing collision avoidance between UGVs. Generally, the model predictive control based formation control has a disadvantage in that it takes a long time to compute control inputs when considering collision avoidance between UGVs. In this paper, in order to overcome this problem, the formation control algorithm is implemented in a distributed manner so that it could be individually controlled. Also, a collision-avoidance method considering real-time is proposed. The proposed formation control algorithm is implemented based on robot operating system (ROS), open source-based middleware. Through the various simulation tests, it is confirmed that the formation control of five UGVs is successfully performed while avoiding collisions between UGVs.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2000년도 제15차 학술회의논문집
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• pp.546-546
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• 2000

This paper designs and implements special objects such as a control object, a I/O object and a file object based on CORBA and DCOM which are suitable to distributed control systems. And interactions among those objects ate analyzed.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2000년도 제15차 학술회의논문집
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• pp.548-548
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• 2000

This paper measures and compares time delays between CORBA, DCOM, TSpaces Objects designed for distributed control systems. To compare time delay for each object, this paper implements the ball and beam control system. And the reasons of delay have been studied.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2003년도 ICCAS
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• pp.2121-2125
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• 2003

This paper proposes a fast distributed constrained power control (FDCPC) with non-stationary relaxation factor to next power update in CDMA cellular power control system. We review unconstrained control algorithms, the distributed power control (DPC), unconstrained second order power control (USOPC) and DPC with stationary relaxation factor (DPCSRF). Under the unconstrained condition, the convergence analysis shows theoretically that the convergence rate of DPC is the fastest one. However, under the constrained control algorithms, DCPC is not the fastest one any more because of transmission power constraint. To improve the convergence speed, the DCPC with non-stationary relaxation factor (FDCPC) are proposed. Under the constrained condition, the convergence rate of FDCPC outperforms that of DCPC and CSOPC.

• International Journal of Internet, Broadcasting and Communication
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• 제8권1호
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• pp.64-68
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• 2016

These fields are integrated to visualize and finalize the proposed development, in simulation environment. SCADA (supervisory control and data acquisition) systems and distributed control systems (DCSs) are widely deployed in all over the world, which are designed to control the industrial infrastructures, in real ways. To supervise and control the various parts of designed systems; trends to require a deep knowledge to understand the overall functional needs of industries, which could be a big challenge. Industrial field devices (or network sensors) are usually distributed in many locations and are controlled from centralized site (or main control center); the communication provides various signs of security issues. To handle these issues, the research contribution will twofold: a method using cryptography is deployed in critical systems for security purposes and overall transmission is controlled from main controller site. At controller site, multimedia components are employed to control the overall transmission graphically, such as system communication, bytes flows, security embedded parameters and others, by the means of multimedia technology.