• Journal of Institute of Control, Robotics and Systems
• /
• v.14 no.10
• /
• pp.969-976
• /
• 2008

A position control problem is studied for UEV(Unmanned Expedition Vehicles), which is to follow pre-determined paths via fixed way-points. Hybrid control systems are used for position control of UEV depending on the operating condition. Speed control consists of three controllers: PID control, adaptive PI control, and neural network. Heading control consists of two controllers, PID and adaptive PID control. The controllers are selected based on the changes of road conditions. We suggest an adaptive PI control algorithm for speed control and an transition management algorithm among the controllers. The algorithm adapts the road conditions and variation of vehicle dynamical characteristics and selects a suitable controller.

• 제어로봇시스템학회:학술대회논문집
• /
• 2000.10a
• /
• pp.350-350
• /
• 2000

Since the heat exchange system, such as the boiler of power plant, gas turbine, and radiator require a high rate heat efficiency and the efficiency of these systems is depended on the control methods. However, it is important f3r operator to understand control system of these systems. In order to properly apply control equipment to these process control systems, such as boiler, any other heat process, or process control system it is necessary to understand the basic aspects and operation principle of the process that relate control, interrelationships of the process characteristics, and the dynamics that are involved. Generally, PID controllers are used in these systems but it is difficult for engineer to understand the complex dynamics and the tuning method because of the coupling action and disturbance in the system loop. In this paper, we design an effective experimental system fur automatic control education and analyze its characteristics through experimental system and industrial plant control software to study how they can team automatic control system by experiments.

• International Journal of Fuzzy Logic and Intelligent Systems
• /
• v.9 no.4
• /
• pp.309-314
• /
• 2009

This paper presents implementation of the adaptive neuro-fuzzy control method. Control performance of the adaptive neuro-fuzzy control method for a popular inverted pendulum system is evaluated. The inverted pendulum system is designed and built as an education kit for educational purpose for engineering students. The educational kit is specially used for intelligent control education. Control purpose is to satisfy balancing angle and desired trajectory tracking performance. The adaptive neuro-fuzzy controller has the Takagi-Sugeno(T-S) fuzzy structure. Back-propagation algorithm is used for updating weights in the fuzzy control. Control performances of the inverted pendulum system by PID control method and the adaptive neuro-fuzzy control method are compared. Control hardware of a DSP 2812 board is used to achieve the real-time control performance. Experimental studies are conducted to show successful control performances of the inverted pendulum system by the adaptive neuro-fuzzy control method.

• Proceedings of the Earthquake Engineering Society of Korea Conference
• /
• 2003.09a
• /
• pp.442-449
• /
• 2003

This paper presents a robust hybrid control system for seismic response control of a cable-stayed bridge. Because multiple control devices are operating, a hybrid control system could alleviate some of restirctions and limitations that exist when each system is acting alone. A LQG algorithm with on-off control scheme, H$_2$ and H$_{\infty}$ control algorithms with various frequency weighting filters are used to improve the controller robustness of the active control part in the hybrid control system. The numerital simulation results show that control performances of robust hybrid control systems are similar to those of the hybrid control system with LQG algorithm. Furthermore, it is verified that robust hybrid control systems are more robust than the hybrid control system with LQG algorithm and there are no signs of instabilities in the $\pm$5％ stiffness matrix perturbed system. Therefore, the proposed hybrid control system have a good robustness for stiffness matrix perturbation without loss of control effectiveness.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.14 no.5
• /
• pp.134-140
• /
• 2015

A control program of an engine control module (ECM) was developed, and its control performance was verified on a 750Ps marine diesel engine. The control method was designed for an engine rotational speed control system. For ECM hardware, the commercial rapid control prototype (RCP) ECM was used. The programming tool for control algorithm development was the MatLab/Simulink. The main control algorithm assembled many control models as engine cranking, run, and stall. Each model has sub-models to input/output control signals. The target engine speed was input signal from a speed control lever, and control output signal of the ECM was sent to the unit-injectors for fuel injection. The engine test was performed under various conditions of engine rotational speeds and dynamometer loads. The test results show that the control function of the ECM is suitable for electrical marine diesel engines.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2003.06a
• /
• pp.438-442
• /
• 2003

For an efficient sliding mode control system stability and chattering avoidance should be guaranteed. A continuation method using boundary layer is well known as one solution for this. However since not only model uncertainties and disturbances but also control task itself is variable. it is practically impossible to set controller parameters - control discontinuity, control bandwidth, boundary layer thickness - in advance. In this paper first an adaptation law of control discontinuity is introduced to assure system stability and then fuzzy logic based tuning algorithm of design parameters is applied based on monitored performance indices of tracking error, control chattering, and model precision. In the end maximum control bandwidth not exciting unmodeled dynamics and minimum control discontinuity, boundary layer thickness making system stable and free of chattering are found respectively. This eliminates control chattering and enhances control accuracy as much as possible under given control situation. In order to demonstrate the validity of the proposed algorithm safe headway maintenance control for autonomous transportation system is simulated. The control results show that the proposed algorithm guarantees system stability all the time and tunes control parameters consistently and in consequence implements an efficient control in terms of both accuracy and actuator chattering.

• Korean Journal of Child Studies
• /
• v.26 no.6
• /
• pp.305-319
• /
• 2005

The subjects of this study were 210 fathers and mothers of 5-year-old preschoolers. Data were analyzed by correlation and regression. Results showed that "activity" was negatively related to children's self-control. Adaptability and rhythmics, however, were positively related to children's self-control in girl Mothers' imperative control was negatively but her position-oriented control and person-oriented control were positively related to the elf-control of boys. Mothers' position-oriented control and person-oriented control were positively related to the self-control of girls. but there were no significant relations found between mothers' imperative control and children's self-control Fathers' person-oriented control was related to the self-control of boys. Finally, both for boys and girls, "activity" was the most influential variable in children's self-control among the four sub-scales of temperament and parental modes of verbal control.

• Structural Engineering and Mechanics
• /
• v.52 no.5
• /
• pp.919-935
• /
• 2014

In this study, the control of the shape of pre-stressed cable structures and the effective control element were examined. The process of deriving the displacement control equations using the force method was explained, and the concurrent control scheme (CCS) and the sequence control scheme (SCS) were proposed. To explain the control scheme process, the quadrilateral cable net model was adopted and classified into a regular model and an irregular model for the analysis of the control results. In the control analysis of the regular model, the CCS and SCS analysis results proved reliable. For the SCS, the errors occur in the control stage and varied according to the control sequence. In the control analysis of the irregular model, the CCS analysis result also proved relatively reliable, and the SCS analysis result with the correction of errors in each stage was found nearly consistent with the target shape after the control. Finally, to investigate an effective control element, the Geiger cable dome was adopted. A set of non-redundant elements was evaluated in the reduced row echelon form of a coefficient matrix of control equations. Important elements for shape control were also evaluated using overlapping elements in the element sets, which were selected based on cable adjustments.

• Journal of Biosystems Engineering
• /
• v.14 no.3
• /
• pp.168-180
• /
• 1989

This study was attempted to develop the electronic-hydraulic hitch control system for position control of tractor plow and investigate the control performance of the system through experiments. Experiments were carried out to investigate the responses of the system to the step and sinusoidal inputs in position control. The effects of control mode, hydraulic flow rate, reference deadband, and proportional constant on control performance of the system were investigated. The following conclusions were derived from the study; 1. For the position control system operated on on-off control mode, positions of implement were controlled within ${\pm}0.73^{\circ}{\sim}{\pm}1.46^{\circ}$ in rockshaft angle to the reference position when the hydraulic flow rates were 5~15 l/min. For the position control system operated on PWM control mode, positions of implement were controlled within ${\pm}0.73^{\circ}$ to the reference position regardless of hydraulic flow rates. It means that the implement could be positioned more accurately to the reference position on PWM control mode than on on-off control mode. 2. As results of the frequency responses of the position control systems, no clear difference in control performance between on-off control and PWM control modes was found. As the hydraulic flow rates increased, the corner frequencies of amplitude attenuation and phase-angle change increased. It means that the control performance of the system could be improved as the hydraulic flow rate increases.

• International Journal of Aeronautical and Space Sciences
• /
• v.8 no.1
• /
• pp.10-20
• /
• 2007

For spacecraft attitude control, reaction wheel (RW) steering laws with more than three wheels for three-axis attitude control can be derived by using a control allocation (CA) approach.1-2 The CA technique deals with a problem of distributing a given control demand to available sets of actuators.3-4 There are many references for CA with applications to aerospace systems. For spacecraft, the control torque command for three body-fixed reference frames can be constructed by a combination of multiple wheels, usually four-wheel pyramid sets. Multi-wheel configurations can be exploited to satisfy a body-axis control torque requirement while satisfying objectives such as minimum control energy.1-2 In general, the reaction wheel steering laws determine required torque command for each wheel in the form of matrix pseudo-inverse. In general, the attitude control command is generated in the form of a feedback control. The spacecraft body angular rate measured by gyros is used to estimate angular displacement also.⁵ Combination of the body angular rate and attitude parameters such as quaternion and MRPs(Modified Rodrigues Parameters) is typically used in synthesizing the control command which should be produced by RWs.¹ The attitude sensor signals are usually corrupted by noise; gyros tend to contain errors such as drift and random noise. The attitude determination system can estimate such errors, and provide best true signals for feedback control.⁶ Even if the attitude determination system, for instance, sophisticated algorithm such as the EKF(Extended Kalman Filter) algorithm⁶, can eliminate the errors efficiently, it is quite probable that the control command still contains noise sources. The noise and/or other high frequency components in the control command would cause the wheel speed to change in an undesirable manner. The closed-loop system, governed by the feedback control law, is also directly affected by the noise due to imperfect sensor characteristics. The noise components in the sensor signal should be mitigated so that the control command is isolated from the noise effect. This can be done by adding a filter to the sensor output or preventing rapid change in the control command. Dynamic control allocation(DCA), recently studied by Härkegård, is to distribute the control command in the sense of dynamics⁴: the allocation is made over a certain time interval, not a fixed time instant. The dynamic behavior of the control command is taken into account in the course of distributing the control command. Not only the control command requirement, but also variation of the control command over a sampling interval is included in the performance criterion to be optimized. The result is a control command in the form of a finite difference equation over the given time interval.⁴ It results in a filter dynamics by taking the previous control command into account for the synthesis of current control command. Stability of the proposed dynamic control allocation (CA) approach was proved to ensure the control command is bounded at the steady-state. In this study, we extended the results presented in Ref. 4 by adding a two-step dynamic CA term in deriving the control allocation law. Also, the strict equality constraint, between the virtual and actual control inputs, is relaxed in order to construct control command with a smooth profile. The proposed DCA technique is applied to a spacecraft attitude control problem. The sensor noise and/or irregular signals, which are existent in most of spacecraft attitude sensors, can be handled effectively by the proposed approach.