• 한국정밀공학회지
• /
• 제25권12호
• /
• pp.89-99
• /
• 2008

In this paper, the position tracking control problem of the servo system with nonlinear dynamic friction is issued. The nonlinear dynamic friction contains a directly immeasurable friction state variable and the uncertainty caused by incomplete parameter modeling and its variations. In order to provide the efficient solution to these control problems, we propose the composite control scheme, which consists of the robust friction state observer, the FNN approximator and the approximation error estimator with sliding mode control. In first, the sliding mode controller and the robust friction state observer is designed to estimate the unknown internal state of the LuGre friction model. Next, the FNN estimator is adopted to approximate the unknown lumped friction uncertainty. Finally, the adaptive approximation error estimator is designed to compensate the approximation error of the FNN estimator. Some simulations and experiments on the servo system assembled with ball-screw and DC servo motor are presented. Results show the remarkable performance of the proposed control scheme. The robust friction state observer can successfully identify immeasurable friction state and the FNN estimator and adaptive approximation error estimator give the robustness to the proposed control scheme against the uncertainty of the friction parameters.

• 한국공작기계학회논문집
• /
• 제11권3호
• /
• pp.93-101
• /
• 2002

The effect of nonlinear friction in the low velocity is dominant in precise controlled mechanisms and it is difficult to identify the friction effect. The friction model which Canudas suggested so called, LuGre model is well expressed the friction effect as Streibeck in the law velocity. But it\`s model parameters were estimated continuously in operation for precise control. This paper suggests the sliding mode controller and observer for compensating the friction effect. Experimental results for a ball-screw system show that the proposed method has a good performance especially in the low velocity.

• 한국생산제조학회지
• /
• 제19권3호
• /
• pp.394-401
• /
• 2010

In this article, we investigate a robust friction compensation scheme for the purpose of accomplishing precision positioning performance a servo mechanical system with nonlinear dynamic friction. To estimate the friction state and tackle robustness problem for uncertainty, a RFNN and reconstructed error compensator as well as a robust friction state observer are developed. The asymptotic stability of the series of friction compensation methodologies are verified from the Lyapunov's stability theory. Some simulations and experiments on a servo mechanical system were carried out to evaluate the effectiveness of the proposed control scheme.

• 중소기업융합학회논문지
• /
• 제4권1호
• /
• pp.17-29
• /
• 2014

무선 캡슐 내시경은 소장 질환을 진단하는 등의 어려움을 해결하는 진화 의료 기기로서 중요한 역할을 했다. 그것은 제한된 크기와 기능 때문에 몇 가지 단점이 있다. 가장 큰 장애물은 자기 운동 장애에서 속도 문제를 제공할 수 없다는 점이다. 따라서, 인간의 소화 시스템의 특성을 간단히 내시경 역학의 정보를 얻기 위해, 특히 소장을 소개한다. 조건 추출을 확인하기 위해서 LuGre 모델이라는 새로운 동적 마찰 모델을 도입하고 명확하게 특성 및 모델의 사용을 얻기 위하여 분석한다. 캡슐 내시경의 실제 상황과 관련된 매개 변수의 고려하여 매트랩 시뮬링크는 모델을 작성하는 데 적용하고 기능을 발견 할 수있는 시뮬레이션을 통해 확인하였다.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2008년도 추계학술대회 논문집
• /
• pp.127-128
• /
• 2008

• 한국공작기계학회논문집
• /
• 제18권1호
• /
• pp.50-58
• /
• 2009

For precise tracking control of a servo system with nonlinear friction, a robust friction compensation scheme is presented in this paper. The nonlinear friction is difficult to identify the friction parameters exactly through experiments. Friction parameters can be also varied according to contact conditions such as the variation of temperature and lubrication. Thus, in order to overcome these problems and obtain the desired position tracking performance, a robust adaptive back-stepping control scheme with a dual friction observer is developed. In addition, to estimate lumped friction uncertainty due to modeling errors, a DEKF recurrent neural network and adaptive reconstructed error estimator are also developed. The feasibility of the proposed control scheme is verified through the experiment fur a ball-screw system.

• 전자공학회논문지
• /
• 제51권1호
• /
• pp.202-208
• /
• 2014

로봇 시스템에 작용하는 마찰력은 비선형 형태이며 특히 저속에서의 정밀 제어를 어렵게 만든다. 본 논문에서는 로봇 연구에서 자주 활용되고 있는 벤치마크 로봇 시스템의 단축 모델에 대한 동적 마찰 보상 문제를 다룬다. 마찰 모델은 동적 특성 및 다양한 효과를 나타낼 수 있도록 비선형 동적 모델인 LuGre 모델을 고려한다. 본 논문에서 제안하는 제어기는 두 부분으로 구성된다. 동적 마찰의 추정 및 보상을 위해 Dual 관측기 기반의 적응 제어기를 사용한다. 마찰 추정 오차 및 나머지 외란을 보상하기 위해 PI 관측기를 추가로 설계한다. 모의실험을 통해 비선형 동적 마찰이 벤치마크 로봇 시스템의 제어 성능에 미치는 영향을 확인하고 제안된 제어기를 사용함으로써 동적 마찰에 대한 제어 성능이 향상됨을 보인다.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2003년도 춘계학술대회
• /
• pp.799-804
• /
• 2003

Friction phenomenon can be described as two parts which are pre-sliding and sliding regions. In motion of the sliding region, friction forces depend on the velocity of the system and are known as Coulomb, stick-slip, stribeck effect and viscous friction. The pre-sliding region, which is before breakaway, depends on the position of the system. The motion of friction in the sliding region can be described as the LuGre model. But the pre-sliding motion of friction, which has hysteresis characteristics in general, is not known widely. Therefore, an improved friction model, which can describe the motion of friction in the pre-sliding region, is proposed in this paper. And simulation and experimental results show the effectiveness of the proposed friction model for precise tracking control systems.

• 한국자동차공학회논문집
• /
• 제12권4호
• /
• pp.146-153
• /
• 2004

This paper presents a discrete analysis approach to investigate the performance of dual mass flywheel (DMF). In the discrete analysis, arcspring installed between the flywheels is modeled as N- discrete elements. Each element consists of mass, spring and nonlinear friction element. LuGre friction model is used to describe nonlinear friction characteristic. Based on the dynamic models of the DMF, clutch, engine, manual transmission and vehicle, a DMF performance simulator is developed using MATLAB Simulink. Simulation results of the engine speed, driveshaft torque and vehicle velocity are compared with test results. It is found that the discrete DMF model describes the vehicle behavior closely, especially during the clutch actuation period.

• 전기학회논문지P
• /
• 제59권2호
• /
• pp.163-172
• /
• 2010

A robust positioning control system has been studied using a friction parameter observer and a recurrent fuzzy neural network based on the sliding model. To estimate a nonlinear friction parameters of the LuGre friction model, a dual friction model-based observer is introduced. In addition, an approximating method for a system uncertainty has been developed using a recurrent fuzzy neural network technique to improve positioning performance. Experimental results have been presented to validate the performance of a proposed intelligent compensation scheme.