• International Journal of Automotive Technology
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• 제3권4호
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• pp.165-170
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• 2002

For a vehicle Anti-lock Braking System (ABS), the control target is to maintain friction coefficients within maximum range to ensure minimum stopping distance and vehicle stability. But in order to achieve a directionally stable maneuver, tire side forces must be considered along with the braking friction. Focusing on combined braking and turning operation conditions, this paper presents a new control scheme for an ABS controller design, which calculates optimal target wheel slip ratio on-line based on vehicle dynamic states and prevailing road condition. A fuzzy logic approach is applied to maintain the optimal target slip ratio so that the best compromise between braking deceleration, stopping distance and direction stability performances can be obtained for the vehicle. The scheme is implemented using an 8-DOF nonlinear vehicle model and simulation tests were carried out in different conditions. The simulation results show that the proposed scheme is robust and effective. Compared with a fixed-slip ratio scheme, the stopping distance can be decreased with satisfactory directional control performance meanwhile.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1998년도 제13차 학술회의논문집
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• pp.301-307
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• 1998

The goal of this paper is to describe an advanced method of the fault diagnois using Control Theory with reference to a crack detection, a new way to localize the crack position under infulence of the plant disturbance and white measurement noise on a rotating shaft. As a first step, the shaft is physically modelled with a finite element method as usual and the dynamic mathematical model is derived from it using the Hamilton - principle and in this way the system is modelled by various subsystems. The equations of motion with crack is established by adaption of the local stiffness change through breathing and gaping from the crack to the equation of motion with un-damaged shaft. This is supposed to be regarded as reference for the given system. Based on the fictitious model of the time behaviour induced from vibration phenomena measured at the bearings, a nonlinear State Observer is designed in order to detect the crack on the shaft. This is elementary NL- observer(EOB). Using the elementary observer, an Estimator(Observer) Bank is established and arranged at the certain position on the shaft. In case a crack is found and its position is known, the procedure for the estimation of the depth is going to begin.

• Journal of Computational Design and Engineering
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• 제3권4호
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• pp.312-321
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• 2016

Dynamic behaviour of a slider-crank mechanism associated with a smart flexible connecting rod is investigated. Effect of various mechanisms' parameters including crank length, flexibility of the connecting rod and the slider's mass on the dynamic behaviour is studied. Two control schemes are proposed for elastodynamic vibration suppression of the flexible connecting rod and also obtaining a constant angular velocity for the crank. The first scheme is based on feedback linearization approach and the second one is based on a sliding mode controller. The input signals are applied by an electric motor located at the crank ground joint, and two layers of piezoelectric film bonded to the top and bottom surfaces of the connecting rod. Both of the controllers successfully suppress the vibrations of the elastic linkage.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1991년도 하계학술대회 논문집
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• pp.813-816
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• 1991

Direct-drive SCARA-type industrial robots are increasingly used in the assembly process of small mechanical parts as well as electronic components, which uses direct-drive (DD) motors instead of reduction gear-type conventional motors for the actuators of manipulator arms. There are many advantages in using DD motors for robots, such as no backlash, low friction, high mechanical stiffness capability for fast and precise arm control, and high repeatability of positioning. However, there exist a number of difficulties which must be overcome to ensure proper construction and operation; increasing effects of load veriation and nonlinear and coupling dynamics, severe vibration caused by resonance of the manipulator components and low mechanical damping, etc. In order to handle these difficulties, lots of efforts have been made such as reduction of the arm inertia and elimination of the resonance, Performance evaluation of a recently developed, domestic DD robot shows that it works excellently compared with conventional robots. It, however, requires proved reliability and price competitiveness against its foreign counterparts.

• Smart Structures and Systems
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• 제15권4호
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• pp.1103-1120
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• 2015

A self-sensing magnetorheological (MR) damper with embedded piezoelectric force sensor has recently been devised to facilitate real-time close-looped control of structural vibration in a simple and reliable manner. The development and characterization of the self-sensing MR damper are presented based on experimental work, which demonstrates its reliable force sensing and controllable damping capabilities. With the use of experimental data acquired under harmonic loading, a nonparametric dynamic model is formulated to portray the nonlinear behaviors of the self-sensing MR damper based on NARX modeling and neural network techniques. The Bayesian regularization is adopted in the network training procedure to eschew overfitting problem and enhance generalization. Verification results indicate that the developed NARX network model accurately describes the forward dynamics of the self-sensing MR damper and has superior prediction performance and generalization capability over a Bouc-Wen parametric model.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2001년도 ICCAS
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• pp.156.5-156
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• 2001

Stabilized tracking platform in a missile consisting of a flat planar antenna, pitch/yaw gimbals, gear trains, and current controlled DC drive motors for pitch and yaw gimbal must have a capability to track a target as an inertial sensor in the presence of missile body motion such as maneuvering and vibration. Because of this reason, tracking a target from dynamic platform requires a servo architecture that includes a outer tracking loop(position loop) and inner rate loop that stabilizes the line of sight(LOS). This paper presents a gimbaled platform model including nonlinear phenomena due to viscous and Coulomb friction based on experimental data and torque equilibrium equation, the design concept for the inner tacholoop having P controller structure ...

• Smart Structures and Systems
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• 제18권1호
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• pp.17-29
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• 2016

In this paper, the possibility of using human induced loading (HIL) to detect a decrease of tension in the cable-stays of an existing footbridge is investigated. First, a reliable finite elements model of an existing footbridge is developed by calibration with experimental data. Next, estimates of the tension in the cables are derived and their dependency on the modal features of the deck is investigated. The modelling of the HIL is briefly discussed and used to perform the nonlinear, large strain, dynamic finite elements analyses. The results of these analyses are assessed with focus on characterizing the time histories of the tension in the cables under pedestrian crossing and their effects on the deck response for different initial conditions. Finally, the control perspective is introduced in view of further research.

• 한국통신학회논문지
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• 제12권5호
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• pp.527-534
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• 1987

진동에 관한 비선형 1계연립미분방정식을 아나로그 시뮬레이션으로 2상전압제어발진을 시켜 유용성을 확인하였다. 2상신호를 각각 제곱하여 합성하는 부분과 곱셈부분의 실제회로 구성시 복잡하고 가격이 높아지므로 정류 회로와 스위칭회로로 대치하여 회로의 단순화와 가격 저렴화를 이루었다. 본 논문에서 제시된 회로는 제어 압력전압에 주파수가 정확한 비례관계를 가졌고, 응답 속도가 비교적 빠르고 또한 위상오차가 매우 적었으며 주파수비가 10:1 이상에서도 저왜율과 정진폭으로 동작하였다.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2006년도 추계학술대회 논문집
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• pp.1276-1281
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• 2006

In general, the wheel-skid prevention of braking system is very important in modern railway applications. This is because wheel-skid can lead to an increase in noise and vibration from wheels with flat points, as well as an increased braking distance. However conventional anti-skid control has problems because wheel adhension and skid characteristics are very difficult nonlinear systems and time consuming to accurately model. In this paper, we design a fuzzy controller using a model of relation between ahdension and braking force, we show that anti-skid fuzzy controller has a very good performance, performing better than the previous conventional controller.

• Steel and Composite Structures
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• 제18권2호
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• pp.481-496
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• 2015

A Lead Extrusion Damper (LED) is experimentally studied under various frequencies and displacement amplitudes. Experimental results show that the force-displacement hysteresis loops of the LED are close to rectangular and the force-velocity hysteresis loops exhibit nonlinear hysteretic characteristic. Also, the LED can provide consistent energy dissipation without any stiffness degradation. Based on the experimental results, a mathematical model is then proposed to describe the effects of frequency and displacement on property of LED. It can be proved from the comparison between experimental and numerical results that the mathematical model can accurately describe the mechanical behavior of LED. Subsequently, the seismic responses of the Schwedler reticulated shell structure with LEDs are analyzed by ANSYS software, in which three different installation forms of LEDs are considered. It can be concluded that the LED can effectively reduce the displacement and acceleration responses of this type of structures.