• Journal of Institute of Control, Robotics and Systems
• /
• v.16 no.7
• /
• pp.646-654
• /
• 2010

This paper describes an integrated chassis control for a maneuverability, a lateral stability and a rollover prevention of a vehicle by the using of the ESC and AFS. The integrated chassis control system consists of a supervisor, control algorithms and a coordinator. From the measured and estimation signals, the supervisor determines the vehicle driving situation about the lateral stability and rollover prevention. The control algorithms determine a desired yaw moment for lateral stability and a desired longitudinal force for the rollover prevention. In order to apply the control inputs, the coordinator determines a brake and active front steering inputs optimally based on the current status of the subject vehicle. To improve the reliability and to reduce the operating load of the proposed control algorithms, a multi-core ECU platform is used in this system. For the evaluation of this system, a closed loop simulations with driver-vehicle-controller system were conducted to investigate the performance of the proposed control strategy.

• Journal of Institute of Control, Robotics and Systems
• /
• v.17 no.10
• /
• pp.967-982
• /
• 2011

This paper presents a FTNCS (Fault-Tolerant Networked Control System) that can tolerate control surface failure and packet delay/loss in an UAV (Unmanned Aerial Vehicle). The proposed method utilizes the benefits of self-diagnosis by smart actuators along with the control allocation technique. A smart actuator is an intelligent actuation system combined with microprocessors to perform self-diagnosis and bi-directional communications. In the event of failure, the smart actuator provides the system supervisor with a set of actuator condition data. The system supervisor then compensate for the effect of faulty actuators by re-allocating redundant control surfaces based on the provided actuator condition data. In addition to the compensation of faulty actuators, the proposed FTNCS also includes an efficient algorithm to deal with network induced delay/packet loss. The proposed algorithm is based on a Lagrange polynomial interpolation method without any mathematical model of the system. Computer simulations with an UAV show that the proposed FTNCS can achieve a fast and accurate tracking performance even in the presence of actuator faults and network induced delays.

• 제어로봇시스템학회:학술대회논문집
• /
• 1997.10a
• /
• pp.143-146
• /
• 1997

In this paper, we propose a fuzzy-supervised nonlinear H$_{\infty}$ controller which guarantees the robustness and has exact tracking performance for robot manipulator with system parameter uncertainty and exogenous disturbance, The proposed controller which is based on robotic H$_{\infty}$ controller has fuzzy supervisor which decides the optimal control input weighting value through fuzzy making-decision process. Owing to the fuzzy supervisor, The proposed controller can take the optimal control input. Then, we will apply the proposed controller to rigid robot manipulator to verify the performance of our controller.r.

• Proceedings of the Korean Nuclear Society Conference
• /
• 1998.05a
• /
• pp.321-328
• /
• 1998

A controller and sensor fault tolerant system jot a steam generator is designed with fuzzy logic. A structure of the : proposed fault tolerant redundant system is composed of a supervisor and two fuzzy weighting modulators. A supervisor alternatively checks a controlled and a sensor induced performances to identify Which Part, a controller or a sensor, is faulty. In order to analyze controller induced performance both an error and a charge in error of the system output an chosen as fuzzy variables. The fuzzy logic jot a sensor induced performance uses two variables : a deviation between two sensor outputs and its frequency, Fuzzy weighting modulator generates an output signal compensated for faulty input signal. Simulations show that the : proposed fault tolerant control scheme jot a steam generator regulates welt water level by suppressing fault effect of either controllers or sensors. Therefore through duplicating sensors and controllers with the proposed fault tolerant scheme, both a reliability of a steam generator control and sensor system and that of a power plant increase even mote.

• The Transactions of the Korean Institute of Electrical Engineers
• /
• v.35 no.12
• /
• pp.541-554
• /
• 1986

This paper presents the results of driving performance analysis of permanent magnet synchronous motor using a microprocessor based control system. The system consists of three phase power transistor inverters, three phase controlled rectifier, three central processing units, and sensors. The three CPUs are, respectively, used to generate PWM control signals for the inverter generating three phase sine wave, to generate the gate control signals for firing the converter, and to supervise other two CPUs. The supervisor is used to compute PI control algtorithm to three phase reference sine wave for the inverter. It is also used to maintain a constant voltage frequency ratio for the converter operating as a constant torque controller. The inverter CPU retrieves precomputed PWM patterns from look up tables because of computation speed limitations found in almost available microprocessors. The converter CPU also retrieves precomputed gate control patterns from another look-up tables. For protecting the control ststem from any damage by extraordinary over currents, the supervisor receives the data from current sensor, CT, and break down the CB to isolate the circuits from source. A resolver has a good performance characteristics of overall speed range, especially on low speed range. Therefor the speed control accuracy is impoved. The microprocessor based PM synchronous motor control system, thus, has many advantages such as constant torque characteristics, improvement of wave, limitation on extraordinary over currents, improvement of speed control accuracy, and fast response speed control using multi-CPU and look-up tables.

• Proceedings of the Korean Operations and Management Science Society Conference
• /
• 1995.04a
• /
• pp.193-200
• /
• 1995

A shop floor control system(SFCS), a central part of agile manufacturing, performs the production activities required to fill orders. In order to effectively control these activities, CSCW (computer supported cooperative work) is adopted where a supervisor does not exist. In this paper, we define functional perspective of CSCW-based shop floor control using planning, scheduling, and execution functions. In particular, we focus on an execution model that can coordinate the planning and scheduling functions. Execution can be defined informally as a function that downloads and performs a set of scheduled tasks. Execution is also responsible for identifying and resolving various errors whether they come from hardware or software. The purpose of this research is to identify all the execution activities and solving techniques under the assumptions of CSCW-based heterarchical control architecture. This paper also proposes a classification scheme for execution activities of CSCW-based heterarchical control architecture. Petri-nets are used as a unified framework for modeling and controlling execution activities. For solving the nonexistence of a supervisor, A negotiation-based solution technique is utilized.

• 제어로봇시스템학회:학술대회논문집
• /
• 1997.10a
• /
• pp.585-588
• /
• 1997

This paper presents a construction method of logic-based switching control system which operates in widely changing environments. The logic-based switching controller is composed of a family of candidate controllers together with a supervisor. The system does not require any identification schemes of environments. Switching from one candidate controller to another is carried out based on monitoring the output of the system. The basic ideas of adaptation are as follows: (1)each candidate controller is prepared for each environment in advance; (2)the supervisor applies a sequence of speculative controls to a plant with candidate controllers just after the control has started and just after the change of the environment has been detected. It is important that each candidate controller can keep the system stable during a sequence of speculative controls, and the most appropriate candidate controller for the environment to which the system is exposed can be selected before the last speculative control is ended. An application to an antiskid braking system clarifies the effectiveness of the proposed method.

• Journal of Korean Institute of Industrial Engineers
• /
• v.25 no.1
• /
• pp.87-99
• /
• 1999

A shop floor control system(SFCS) performs the production activities required to fill orders. In order to effectively control these activities, the autonomous agent-based heterarchical shop floor control architecture is adopted where a supervisor does not exist. In this paper, we define functional perspective of the heterarchical shop floor control using planning, scheduling, and execution modules. In particular, we focus on an execution module that can coordinate the planning and scheduling modules and a general execution module that easily can be modified to execute the other equipment. The execution module can be defined informally as a module that downloads and performs a set of scheduled tasks. The execution module is also responsible for identifying and resolving various errors whether they come from hardware or software. The purpose of this research is to identify all the execution activities and solving techniques under the assumptions of the heterarchical control architecture. And we model the execution module in object-oriented modelling technique for generalization. The execution module modeled in object-oriented concept can be adopted to the other execution module easily. This paper also proposes a classification scheme for execution activities of the heterarchical control architecture. Petri-nets are used as a unified framework for modeling and controlling execution activities. For solving the nonexistence of a supervisor, a negotiation-based solution technique is utilized.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.16 no.8
• /
• pp.5314-5324
• /
• 2015

The present study was intended to measure the relationship between job stress and job satisfaction among nurses working for a general hospitals. The self-administered questionnaires were given to 312 nurses during the period from February 25 to March 16, 2013. As a results, the level of job satisfaction of subjects was significantly lower in high group than low group in job demand, but it was significantly lower in low group than high group in job control, supervisor support and coworker support. In correlations, job satisfaction were found to be in a negative correlation with job demand, whereas in positive correlation with job control, supervisor and coworker support. In logistic analysis, the odds ratio of job satisfaction on job demand were significantly increased in the high group than in low group, but job control supervisor and coworker support were significantly decreased in the high group than in low group. In hierarchial multiple regression analysis, the affecting factors to the job satisfaction was selected variables such as educational background, work station, subject satisfaction of work, career choice motives, turnover experience, job stress contents(job demand, job control, supervisor support and coworker support). especially, job stress contents was significantly increased of explanatory power of job satisfaction. It suggested that the level of job satisfaction got more power by addition of job stress contents.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.25 no.6
• /
• pp.708-716
• /
• 2019

After the Sewol ferry disaster, the maritime safety supervisor system was introduced to strengthen maritime safety control for coastal vessels. If any critical defect is found in vessel facilities during periodical or occasional guidance and supervision on a vessel, a maritime safety supervisor takes an administrative measure: detention of the vessel until it has been completely corrected. The detention order is one of the most powerful regulations exercised by a maritime safety supervisor. It would not be an overstatement to say that the guidance and supervision conducted by a maritime safety supervisor is very important for the safety of a vessel and protection of the maritime environment. However, the regulatory level of each Regional Office of Oceans and Fisheries toward vessels may vary with the enforcers, and an individual's intentional act or negligence might occur during the execution process. Detention of a coastal vessel by the Regional Office of Ocean and Fisheries can easily lead to delayed navigation, and a vessel owner may suffer economic loss from suspension of a charter party. Nevertheless, the Maritime Safety Act does not prescribe filing a petition for objection to the measure of detention order by a maritime safety supervisor. To overcome this problem, therefore, the objection procedure under the Maritime Safety Act has to be reformed to reclaim a right against an inappropriate detention order measure caused by an individual's intentional act or negligence through a formal objection.