• Journal of the Korean Institute of Intelligent Systems
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• v.16 no.3
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• pp.349-356
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• 2006

A cartpole system is controlled by a control system consisting of two fuzzy controllers cooperating by a CMAC. Each controller uses 2 different input variables and yields the control force provided to the CMAC. The cooperation is due to training of the CMAC supervised by a judge which selects training information for the CMAC between two fuzzy controllers. The control scheme could be appreciated in terms of the tight structure of the controller, simple cooperating scheme due to the CMAC training, and accomplishing control goal that could not be attained by individual controllers.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.9
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• pp.1802-1808
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• 2009

A fault detection observer with finite time convergence characteristics(FT_FDO) is proposed and applied to a fault detection isolation system for a dynamic control system. The FT_FDO is a kind of dual state-observer scheme that provides with the state estimates insensitive to a specified fault and the corresponding fault estimate. The state estimates are processed to get the residual that will be logically compared with other residuals to detect and isolate the fault of interest, and the fault estimate may be used for fault compensation. The FDIS employing the FT_FDOs can be considered to be a multiple observer schemes(MOS) in which FT_FDOs are parallelly driven to generate a set of residuals to be compared each other. Due to the finite time convergence characteristics of the FT_FDO, the predetermined detection delay can be considered in the design stage of FDIS so that any fault of interest can be detected and identified in that time. It evidently resolves a well known difficulty of threshold selection owing to the transient responses of the fault detection observers(FDO) employed in FDIS. An FDIS is constructed for instruments(2-sensor, 1-actuator) in an inverted pendulum control system, and simulations are performed to show the performance of the FDIS and fault tolerant control system.

• The Journal of the Korea institute of electronic communication sciences
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• v.7 no.5
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• pp.1133-1138
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• 2012

In the paper, design of nonlinear sliding surfaces which are based on optimal control is studied, The state trajectory by the input of optimal control was obtained by Frobenius theorem and matrix decomposition method, was set the nonlinear sliding surfaces of the system. The states is maintained to sliding surfaces from initial states. As the result, robustness of the system can be guaranteed throughout an entire response of the system starting form the initial time instance, the uncertainty and external disturbance that can occur during the reaching time is removed, the problem of large control input was solved, and setting the sliding surfaces optimal path was able to reduce the tracking time. The validity of the proposed control scheme is shown in computer simulation for inverted pendulum.

• Journal of Mechanical Science and Technology
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• v.20 no.5
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• pp.602-611
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• 2006

This paper proposes a locomotion pattern and a control method for biped robots with curved soles. First, since the contact point of a supporting leg may arbitrarily move back and forth on the ground, we derived the desired trajectory from a model called the Moving. Inverted Pendulum Model (MIPM) where the Zero Moment Point (ZMP) exists at the supporting point and can be moved intentionally. Secondly, a biped robot with curved soles is an under-actuated system since the supporting point contacting with a point on the ground has no actuator during the single supporting phase. Therefore, this paper proposes a computed-torque control for this under-actuated system using decoupled dynamic equations. A series of computer simulations with a 7-DOF biped robot with curved soles shows that the proposed walking pattern and control method are effective and allow the biped robot to walk fast and stably, and move more like human beings. Also, it is shown that the curved sole shape has superior energy consumption compared to flat soles, and greater efficiency in ascending and descending the stairs.

• Journal of the Korean Institute of Intelligent Systems
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• v.14 no.1
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• pp.112-117
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• 2004

This paper suggests the design and analysis of the fuzzy sliding mode control for a nonlinear system using Takagi-Sugeno(T-S) fuzzy model. In this control scheme, identifying procedure that the input gain matrices in a T-S fuzzy model are manipulated into the same one is needed. The input disturbances generated in the identifying procedure are resolved by incorporating the disturbance treatment method of the conventional sliding mode control. The proposed control strategy can also treat the input disturbances that can not be linearized in the linearization procedure of T-S fuzzy modeling. Design example for the nonlinear system, an inverted pendulum on a cart, demonstrates the utility and validity of the proposed control scheme.

• Journal of Institute of Control, Robotics and Systems
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• v.21 no.4
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• pp.336-341
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• 2015

This paper proposes a balancing and driving control system for a Mecanum wheel ball robot which has a two axis structure and four motors. The inverted pendulum control method is adopted to maintain the balance of the ball robot while it is driving. For the balancing control, an anon-model-based controller has been designed to control the device simply without the need of a complex formula. All the gains of the controller are heuristically adjusted during the experiments. The tilt angle is measured by IMU sensors, which is used to generate the control input of the roll and pitch controller to make the tilt angle zero. For the driving control, the PID control algorithm has been adopted with angles of the wheels and the encoder data. The performance of the designed control system has been verified through the real experiments with the suggested ball robot.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.24 no.4
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• pp.299-309
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• 2014

When biped robots make turns, the ability to walk stably and precisely along any circular path is crucial. In this context, inverse kinematics solutions are found for accurate gait realization, and new zero moment point(ZMP) equations are derived with respect to the cyclindrical coordinate system to facilitate generation of stable walking patterns. Then, appropriate steady and transitional walking patterns are both proposed in form of time functons. Subsequently, walking patterns for a path but of different speeds are generated using the functions and associated formulas, and preliminarily checked for stability based on the ZMP equations. Upon comparison of those cases, one can see how and when robots may fall down during circular walking. Finally, those patterns are put to test on the sample robot by ADAMS(R) along with the inverse kinematics solutions and a new balance control scheme compensating for insufficient stability particulary during the initial transition period. Test results show that the robot can walk along the circular path as predicted at a resonably high speed despite the distributed mass and ground contact effects, validating effectiveness of the suggested approach.

• International Journal of High-Rise Buildings
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• v.3 no.1
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• pp.35-48
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• 2014

In designing a 300 meter high skyscraper expected to be the tallest building in Japan, an earthquake-ridden country, we launched on the full-scale performance based design to ensure redundancy and establish new specifications using below new techniques. The following new techniques are applied because the existing techniques/materials are not enough to meet the established design criteria for the large-scale, irregularly-shaped building, and earth-conscious material saving and construction streamlining for reconstructing a station building are also required: ${\bullet}$ High strength materials: Concrete filled steel tube ("CFT") columns made of high-strength concrete and steels; ${\bullet}$ New joint system: Combination of outer diaphragm and aluminium spray jointing; ${\bullet}$ Various dampers including corrugated steel-plate walls, rotational friction dampers, oil dampers, and inverted-pendulum adaptive tuned mass damper (ATMD): Installed as appropriate; and ${\bullet}$ Foundation system: Piled raft foundation, soil cement earth-retaining wall construction, and beer bottle shaped high-strength CFT piles.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2000.05a
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• pp.249-255
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• 2000

HRIV(Hybrid Rule-Interval Variation) method is presented to stabilize a class of nonlinear systems, where SMC(Sliding Mode Control) and ADC (ADaptive Control) schemes are incorporated to overcome the unstable characteristics of a conventional FLC(Fuzzy Logic Control). HRIV method consists of two modes: I-mode (Integral Sliding Mode PLC) and R-mode(RIV method). In I-mode, SMC is used to compensate for MAE(Minimum Approximation Error) caused by the heuristic characteristics of FLC. In R-mode, RIV method reduces interval lengths of rules as states converge to an equilibrium point, which makes the defined Lyapunov function candidate negative semi-definite without considering MAE, and the new uncertain parameters generated in R-mode are compensated by SMC. In RIV method, the overcontraction problem that the states are out of a rule-table can happen by the excessive reduction of rule intervals, which is solved with a dynamic modification of rule-intervals and a transition to I-mode. Especially, HRIV method has advantages to use the analytic upper bound of MAE and to reduce Its effect in the control input, compared with the previous researches. Finally, the proposed method is applied to stabilize a simple nonlinear system and a modified inverted pendulum system in simulation experiments.

• The Journal of the Korea institute of electronic communication sciences
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• v.2 no.2
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• pp.67-74
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• 2007

Chattering phenomenon is still a large drawback of VSS. To overcome this problem, various approaches have been reported. A new notion of sliding sector has been proposed recently. Inside this sector, a kind of norm of the state decreases without control input. Therefore, so long as the state is constrained inside this sector, the norm of the state approaches to zero. The sliding sector theory is elementary study step and is studied about only linear systems. In this paper, new methods of the tracking control of unstable nonlinear systems using the sliding sector is proposed. This paper analyzes the stability, using Lyapunov function on the sliding sector. Through the computer simulations for an inverted pendulum system, it is verified that sliding sector control is capable to reduce the chattering.