• Transactions on Control, Automation and Systems Engineering
• /
• 제4권4호
• /
• pp.296-304
• /
• 2002

A position tracking control schemes on the precise mechanical system in presence of nonlinear dynamic friction is proposed. A nonlinear dynamic friction is regarded as the bristle friction model to compensate effects of friction. The conventional sliding mode controller often has been used as a non-model-based friction controller, but it has a poor tracking performance in high-precision position tracking application since it completely cannot compensate the friction effect below a certain precision level. Thus to improve the precise position tracking performance, we propose the sliding mode control method combined with the friction-model-based observer having tunable structure of the transient response. Then this control scheme has a good transient response as well as the high precise tracking performance compared with the conventional sliding mode control without observer and the control system with similar type of observer. The experiments on the bali-screw drive table with the nonlinear dynamic friction show the feasibility of the proposed control scheme.

• 한국자동차공학회논문집
• /
• 제11권4호
• /
• pp.173-179
• /
• 2003

In this paper, a real-time multibody vehicle dynamics and control model has been developed for a virtual reality intelligent vehicle simulator. The simulator consists of low PCs for a virtual reality visualization system, vehicle dynamics and control analysis system a control loading system, and a network monitoring system. Virtual environment is created by 3D Studio Max graphic tool and OpenGVS real-time rendering library. A real-time vehicle dynamics and control model consists of a control module based on the sliding mode control for adaptive cruise control and a real-time multibody vehicle dynamics module based on the subsystem synthesis method. To verify the real-time capability of the model, cut-in, cut-out simulations have been carried out.

• 제어로봇시스템학회논문지
• /
• 제16권4호
• /
• pp.329-334
• /
• 2010

This paper presents the design of a neural network based adaptive control for missile. Acceleration of missile by tail fin control cannot be controllable by DMI (Dynamic Model Inversion) directly because it is non-minimum phase system. To avoid the non-minimum phase system, dynamic model inversion is applied with output-redefinition method. In order to evaluate performance of the suggested controllers we selected the three cases such as control surface fail, control surface loss and wing loss for model uncertainty. The corresponding aerodynamic databases to the failure cases were calculated by using the Missile DATACOM. Using a high fidelity 6DOF simulation program of the missile the performance was evaluates.

• 제어로봇시스템학회논문지
• /
• 제13권3호
• /
• pp.268-272
• /
• 2007

These days many scientists make studies of feedback control system for stability on non-linear state and for the maneuver of flying objects. These feedback control systems have to satisfy trajectory condition and angular conditions, that is to say, controllability and stability simultaneously to achieve mission. In this paper, a design methods using model based control system which consists of spiral predictive model, Q-function included into generalized-work function is shown. It is made a clear that the proposed algorithm using SPM maneuvers for controllability and stability at the same time is successful in attaining our purpose. The feature of the proposed algorithm is illustrated by simulation results. As a conclusion, the proposed algorithm is useful for the control of moving objects.

• 한국정보시스템학회지:정보시스템연구
• /
• 제14권3호
• /
• pp.1-8
• /
• 2005

This paper formally defines a role-driven security and access control model of a business process in order eventually to provide a theoretical basis for realizing the secured business process management systems. That is, we propose a graphical representation and formal description of the mechanism that generates a set of role-driven security and access control models from a business process modeled by the information control net(ICN) modeling methodology that is a typical business process modeling approach for defining and specifying business processes. Based upon the mechanism, we are able to design and accomplish a secured business process management system that provides an unified resource access control mechanism of the business process management engine domain's and the application domain's. Finally, we strongly believe that the secured access control policies from the role-driven security and access control model can be easily transformed into the RBAC(Role-based Access Control) model that is a standardized security technology for computer and communications systems of commercial and civilian government organizations.

• 한국통신학회논문지
• /
• 제29권8C호
• /
• pp.1076-1085
• /
• 2004

최근 프라이버시 적용이 IT분야의 가장 중요한 문제의 하나로 대두되고 있다. 프라이버시 보호는 조직의 데이터 처리 시스템에 프라이버시 정책을 적용함으로써 달성 될 수 있다. 전통적인 보안 모델은 다소간 프라이버시 바인딩과 같은 기본적인 프라이버시 요구를 적용하기에 부적절하다. 본 논문은 조직에 프라이버시 정책을 적용할 수 있는 하나의 확장된 역할기반 접근제어 모델을 제안한다. 이 모델은 RBAC과 도메인-타입 적용, 그리고 프라이버시 정책을 결합함으로써 프라이버시 보호와 함께 문맥기반 접근제어를 제공한다. 프라이버시 정책은 역할에 프라이버시 등급을, 데이터에 고객의 프라이버시 선호에 따른 데이터 프라이버시 등급을 부여하는 데이터 사용 정책을 적용함으로써 달성한다. 또 이 모델을 응용에 적용하기 위하여 작은 병원 모델이 사용되었다.

• Journal of Power Electronics
• /
• 제18권5호
• /
• pp.1398-1408
• /
• 2018

In order to further improve the steady-state control performance of model predictive torque control (MPTC), a double-vector-based model predictive torque control without a weighting factor is proposed in this paper. The extended voltage vectors synthesized by two basic voltage vectors are used to increase the number of feasible voltage vectors. Therefore, the control precision of the torque and the stator flux along with the steady-state performance can be improved. To avoid testing all of the feasible voltage vectors, the solution of deadbeat torque control is calculated to predict the reference voltage vector. Thus, the candidate voltage vectors, which need to be evaluated by a cost function, can be reduced based on the sector position of the predicted reference voltage vector. Furthermore, a cost function, which only includes a reference voltage tracking error, is designed to eliminate the weighting factor. Moreover, two voltage vectors are applied during one control period, and their durations are calculated based on the principle of reference voltage tracking error minimization. Finally, the proposed method is tested by simulations and experiments.

• ETRI Journal
• /
• 제41권6호
• /
• pp.838-849
• /
• 2019

We present a permanent magnet-based spherical wheel motor that can be used in omnidirectional mobility applications. The proposed motor consists of a ball-shaped rotor with a magnetic dipole and a hemispherical shell with circumferential air-core coils attached to the outer surface acting as a stator. Based on the rotational symmetry of the rotor poles and stator coils, we are able to model the rotor poles and stator coils as dipoles. A simple physical model constructed based on a torque model enables fast numerical simulations of motor dynamics. Based on these numerical simulations, we test various control schemes that enable constant-speed rotation along arbitrary axes with small rotational attitude error. Torque analysis reveals that the back electromotive force induced in the coils can be used to construct a control scheme that achieves the desired results. Numerical simulations of trajectories confirm that even without explicit methods for correcting the rotational attitude error, it is possible to drive the motor with a low attitude error (<5°) using the proposed control scheme.

• Smart Structures and Systems
• /
• 제31권5호
• /
• pp.437-454
• /
• 2023

Real-time hybrid simulation (RTHS), which has the advantages of a substructure pseudo-dynamic test, is widely used to investigate the rate-dependent mechanical response of structures under earthquake excitation. However, time delay in RTHS can cause inaccurate results and experimental instabilities. Thus, this study proposes a model-based adaptive control strategy using a Kalman filter (KF) to minimize the time delay and improve RTHS stability and accuracy. In this method, the adaptive control strategy consists of three parts-a feedforward controller based on the discrete inverse model of a servohydraulic actuator and physical specimen, a parameter estimator using the KF, and a feedback controller. The KF with the feedforward controller can significantly reduce the variable time delay due to its fast convergence and high sensitivity to the error between the desired displacement and the measured one. The feedback control can remedy the residual time delay and minimize the method's dependence on the inverse model, thereby improving the robustness of the proposed control method. The tracking performance and parametric studies are conducted using the benchmark problem in RTHS. The results reveal that better tracking performance can be obtained, and the KF's initial settings have limited influence on the proposed strategy. Virtual RTHSs are conducted with linear and nonlinear physical substructures, respectively, and the results indicate brilliant tracking performance and superb robustness of the proposed method.

• Journal of Electrical Engineering and Technology
• /
• 제8권2호
• /
• pp.230-237
• /
• 2013

This paper presents a novel nonlinear model of Switched Reluctance Generator (SRG) based on wind Energy Conversion system. Closed loop control with based Proportional Integrator current Chopping Control machine model is used. A Power converter in SRG can be controlled by using PI-CCC proposed model, and can be produced maximum power efficiency and minimize the ripple contents in the output of SRG. A second power converter namely PI based controlled PWM Inverter is used to interface the machine to the Grid. An effective control technique for the inverter, based on the pulse width modulation (PWM) scheme, has been developed to make the line voltage needs less power switching devices and each pair of turbine the generated active power starts increasing smoothly. This proposed control scheme feasibility and validity are simulated on SIMULINK/SIM POWER SYSTEMS only.