• 대한기계학회논문집A
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• 제23권11호
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• pp.1982-1992
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• 1999

This paper presents a novel concept of cargo handling system adapted for a sea port subjected to severe time-varying tide. The proposed system can perform loading or unloading by using a sort of hydraulic elevator associated with real-time position control. In order to achieve a proof-of-concept, a small-sized laboratory model of the cargo handling system is designed and built. The model consists of three principal components container palette transfer (CPT) car, platform with lifting columns, and cargo ship. The platform activated by electro-rheological (ER) valve-cylinders is actively controlled to track the position of the cargo ship subjected to be varied due to the time-varying tide and wave motion. Following the derivation of the dynamic model for the platform and cargo ship motions, an appropriate control scheme is formulated and implemented. The location of the CPT car is sensed by a set of photoelectric switches and controlled via sequence controller. On the other hand, a sliding mode controller (SMC) is adopted as the position controller for the platform. Both simulated and measured control results are presented to demonstrate the effectiveness of the proposed cargo system.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2000년도 제15차 학술회의논문집
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• pp.506-506
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• 2000

To improve control performance of a non-linear system, many other researches have used the sliding mode control algorithm. The sliding mode controller is known to be robust against nonlinear and unmodeled dynamic terms. However. this algorithm raises the inherent chattering caused by excessive switching inputs around the sliding surface. Therefore, in order to solve the chattering problem and improve control performance, this study has developed the sliding mode controller with a perturbation estimator using the observer-based fuzzy adaptive network generates the control input for compensating unmodeled dynamics terms and disturbance. And, the weighting parameters of the fuzzy adaptive network are updated on-line by adaptive law in order to force the estimation errors to converge to zero. Therefore, the combination of sliding mode control and fuzzy adaptive network gives rise to the robust and intelligent routine. For evaluating control performance of the proposed approach. tracking control simulation is carried out for the hydraulic motion simulator which is a 6-degree of freedom parallel manipulator.

• Journal of Mechanical Science and Technology
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• 제18권4호
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• pp.535-549
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• 2004

This paper proposes a sliding mode controller with fuzzy adaptive perturbation compensator(FAPC) to get a good control performance and reduce the chatter, The proposed algorithm can reduce the chattering because the proposed fuzzy adaptive perturbation compensator compensates the perturbation terms. The compensator computes the control input for compensating unmodeled dynamic terms and disturbance by using the observer-based fuzzy adaptive network(FAN) The weighting parameters of the compensate. are updated by on-line adaptive scheme in order to minimize the estimation error and the estimation velocity error of each actuator. Therefore, the combination of sliding mode control and fuzzy adaptive network gives the robust and intelligent routine to get a good control performance. To evaluate the control performance of the proposed approach, tracking control is experimentally carried out for the hydraulic motion platform which consists of a 6-DOF parallel manipulator.

• 동력기계공학회지
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• 제11권3호
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• pp.59-65
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• 2007

In this study, 6-DOF simulator using pneumatic cylinder driving apparatus was manufactured because a pneumatic cylinder driving apparatus is superior to electric driving motor and hydraulic actuator, which used in traditional 6-DOF simulator, in competitive price and acceleration performance, and, 6-DOF motion can be realized at a low price in case that relatively low load is imposed on the simulator. The possible range of pose control of the simulator was investigated by inverse kinematics, and, it was controlled by a linear controller derived from linear model of the simulator. The Experimental results show that the simulator follows given coordinate well.

• Journal of Mechanical Science and Technology
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• 제19권3호
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• pp.778-791
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• 2005

A novel pneumatic artificial muscle actuator (PAM actuator), which has achieved increased popularity to provide the advantages such as high strength and high power/weight ratio, low cost, compactness, ease of maintenance, cleanliness, readily available and cheap power source, inherent safety and mobility assistance to humans performing tasks, has been regarded during the recent decades as an interesting alternative to hydraulic and electric actuators. However, some limitations still exist, such as the air compressibility and the lack of damping ability of the actuator bring the dynamic delay of the pressure response and cause the oscillatory motion. Then it is not easy to realize the performance of transient response of pneumatic artificial muscle manipulator (PAM manipulator) due to the changes in the external inertia load with high speed. In order to realize satisfactory control performance, a variable damper-Magneto­Rheological Brake (MRB), is equipped to the joint of the manipulator. Superb mixture of conventional PID controller and a phase plane switching control method brings us a novel controller. This proposed controller is appropriate for a kind of plants with nonlinearity, uncertainties and disturbances. The experiments were carried out in practical PAM manipulator and the effectiveness of the proposed control algorithm was demonstrated through experiments, which had proved that the stability of the manipulator can be improved greatly in a high gain control by using MRB with phase plane switching control method and without regard for the changes of external inertia loads.

• Advances in nano research
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• 제9권3호
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• pp.133-145
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• 2020

In this study, nonlinear vibrations and dynamic instabilities of a smart embedded micro shell conveying varied fluid flow and subjected to the combined electro-thermo-mechanical loadings are investigated. With the aim of designing new hydraulic sensors and actuators, the piezoelectric materials are employed for the body and the effects of applying electric field on the stability of the system as well as the induced voltage due to the dynamic behavior of the system are studied. The nonlocal piezoelasticity theory and the nonlinear cylindrical shell model in conjunction with the energy approach are utilized to mathematically modeling of the structure. The fluid flow is assumed to be isentropic, incompressible and fully develop, and for more generality of the problem both steady and time dependent flow regimes are considered. The mathematical modeling of fluid flow is also carried out based on a scalar potential function, time mean Navier-Stokes equations and the theory of slip boundary condition. Employing the modified Lagrange equations for open systems, the nonlinear coupled governing equations of motion are achieved and solved via the state space problem; forth order numerical integration and Bolotin's method. In the numerical results, a comprehensive discussion is made on the dynamical instabilities of the system (such as divergence, flutter and parametric resonance). We found that applying positive electric potential field will improve the stability of the system as an actuator or vibration amplitude controller in the micro electro mechanical systems.

• 한국소음진동공학회논문집
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• 제26권1호
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• pp.82-88
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• 2016

This paper proposes a new type of semi-active direct-drive valve(DDV) car suspension system using piezoelectric actuator associated with displacement amplifier. As a first step, controllable piezoelectric DDV damper is designed and governing equation of a quarter-vehicle suspension system consisting of sprung mass, spring, tire and the piezostack DDV damper is constructed. After deriving the equations of the motion, in order to control spool displacement and damping force the skyhook controller is designed and applied. The performance evaluation of the proposed semi-active suspension system is conducted with different displacement of spool. Then, the ride comfort analysis is undertaken in time domain with bump road profile.

• 대한조선학회논문집
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• 제36권2호
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• pp.61-71
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• 1999

본 연구에서는 조수간만의 차가 큰 항만에 적합한 새로운 하역 시스템을 제안하였다. 새로운 하역 시스템은 기존의 갑문 이용 방식 대신에 일종의 유압 엘리베이터를 사용함으로써 조수간만의 차에 따라 변하는 선박의 높이로 실시간 제어하여 선적 흑은 하역을 하는 방식이다. 한번에 대량의 컨테이너를 처리하기 위해 컨테이너 팔레트 운송타를 도입함으로써 기존 시스템에 비해 시간당 처리능력을 높일 수 있고, 선적 및 하역의 전 과정을 자동화함으로써 작업 효율을 극대화할 수 있도록 하였다. 새로운 하역 시스템의 개념 입증을 위해 소형 하역 시스템 모델을 설계 제작하였다. 제작된 모델은 컨테이너 팔레트 운송차, 플랫폼과 리프트 칼럼의 복합 구조물, 그리고 전용 운반선으로 구성된다. ER(electro-rheological) 밸브-실린더에 의해 구동되는 플랫폼은 조수간만의 차와 과도에 의해 변하는 선박의 높이를 능동적으로 추적 제어하게 된다. 동적 모델성을 통해 플랫폼의 운동 지배 방정식을 도출하였고, 파도 가진으로 인한 선박의 거동 및 조수간만의 차를 모델링하였다. 선적 및 하역의 자동화와 플랫폼의 정확한 위치 제어를 위해 시퀀스 제어기와 PID(proportional-integral-derivative) 위치 제어기가 연계된 제어 시스템을 구성하였다. 컴퓨터 시뮬레이션과 실험을 통해 제안된 하역 시스템의 유용성을 입증하였다.