• Proceedings of the KIEE Conference
• /
• 2005.07d
• /
• pp.2558-2560
• /
• 2005

본 논문에서는 마찰력과 질량은 수직항력에 의해 관계하고, 시스템 입출력 관계에서도 도출할 수 있음에 착안하여, LuGre 모델을 기반으로 하는 수직항력 관측이 가능한 보상기 적용과 동시에 제어 입력과 시스템 출력 관계를 적응규칙을 통해 질량추정기를 설계하여 제어 입력의 스케일로 사용함으로써 그 성능을 더욱 향상시키고자 하였다.

• Journal of Drive and Control
• /
• v.10 no.1
• /
• pp.1-6
• /
• 2013

The paper describes a technique that compensates a friction in pneumatic cylinder to perform the position control. The friction is one of the most common nonlinearities present in pneumatic actuating systems. For accurate position control and low velocity control, control strategies usually rely on accurate estimation of friction. This paper presents a observer to estimate the friction force in the pneumatic cylinder from the pressures in cylinder chambers. Also, the stiction compensation of a pneumatic cylinder is obtained by adding pulses to the control signal using impulsive control. The characteristics of the pulses in impulsive control are determined from the control action. The simulation results are proved that the method proposed here is effective.

• Transactions of the Korean Society of Machine Tool Engineers
• /
• v.12 no.6
• /
• pp.77-83
• /
• 2003

This paper deals with a position control problem of a hydraulic proportional position control system using a nonlinear friction compensation control. As nonlinear friction, stiction and coulomb friction forces are considered and modeled as deadzone and external disturbance respectively. In order to compensate this nonlinearities, we designed the controller which is the adaptive friction compensator using discrete time Model Reference Adaptive Control method in this paper. Digital Signal Processing board is employed for data acquisition and manipulation. The experimental results show that response is slow and steady-state error cannot be compensated properly without friction compensation but this compensator is effective to obtain fast response and good steady-state response.

• Journal of the Korean Society of Manufacturing Technology Engineers
• /
• v.7 no.4
• /
• pp.130-135
• /
• 1998

This paper deals with a position control problem of a hydraulic proportional position control system using a friction compensation control. There are many nonlinearities in hydraulic systems. With only proportional controller, response is slow and steady-state error cannot be compensated properly. Controller designed in this paper achieves fast transient response through the velocity and acceleration feedback and good steady-state response through the friction compensator. A/D and D/A board is employed for data acquisition and manipulation. The experimental results are compared with computer simulation results using Matlab.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.21 no.2
• /
• pp.252-260
• /
• 1997

In this paper, a friction compensation method using a disturbance observer is proposed for an impedance control of pneumatic manipulator. It is assumed that the generated torque by a pneumatic actuator can be estimated based on the pressure signals and the discharge volume. In order to improve the dynamic characteristics of the pneumatic actuator driven by meter out method, we construct the inner torque control system by feeding back the generated torque. In order to reduce the influence of disturbances comprising friction torque and parameter variations of plant, the impedance control system is constructed with a disturbance observer which estimates the disturbances based on the generated torque of pneumatic actuator, the angular velocity and the reaction torque. From some experiments, it is confirmed that the proposed control system is effective to improve the robustness for the friction torque in the impedance control of a pneumatic manipulator.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.45 no.11
• /
• pp.967-974
• /
• 2017

Reaction wheel shows nonlinear torque response on low-speed region due to friction. Thus precise satellite attitude control on this region is hard to achieve. Previous research tries to solve this problem, by compensating friction or applying dither command. However, due to difficulties of drag torque modeling or frequent zero wheel speed crossing, these methods are not suitable to apply on the real satellite attitude control. To solve this problem, we propose the attitude controller gain adjustment method based on the attitude error.

• Proceedings of the KSLP Conference
• /
• 2003.11a
• /
• pp.146-146
• /
• 2003

연인두 폐쇄 부전으로 보상조음이 있을 때, 말 명료도를 저하시킬 뿐 아니라 실제의 연인두 기능이 과소평가 될 수 있으므로 이에 대한 감별 및 언어치료가 필수적이다. 본 연구에서는 연인두 폐쇄 부전 환자들에서 보상조음의 출현율을 알아보고 어떤 음소들이 영향을 받는지 살펴보고자 하였다. 또한 연령과 과비성의 정도에 따른 차이도 살펴보았다. 1998년 3월부터 2003년 6월까지 삼성서울병원에서 연인두 폐쇄 부전으로 진단 받고 언어치료를 받지 않았거나 언어치료 경험은 있지만 일반화되지 않고 중단된 환자 105명의 조음 및 공명 평가 자료를 분석하였다. 연령은 평균 11.3세(2.1세부터 63세)였고 7세 이하의 아동집단이 65명, 성인집단이 40명이었다. 조음은 구강압력자음인 파열음, 마찰음, 파찰음에서의 보상조음의 유무 및 종류를 분석하였다. 과비성의 정도는 경도, 중도, 심도로 평가하였다. (중략)

• Proceedings of the Korean Institute of Navigation and Port Research Conference
• /
• v.1
• /
• pp.405-413
• /
• 2006

In general mechanical servo systems, friction deteriorates the performance of controllers by its nonlinear characteristics. Especially, friction phenomenon causes steady-state tracking errors and limit cycles in position and velocity control systems, even though gains of controllers are tuned well in linear system model. Even if sensor is used higher accuracy level, it is difficult to improve tracking performance of the position to the same level with a general control method such as PID type. Therefore, many friction models were proposed and compensation methods have been researched actively. In this paper, we consider that the variation of mover's mass is various by loading and unloading. The normal force variation occurs by it an other parameters. Therefore, the proposed control system is composed of main position controller and a friction compensator. A parameter estimator for a nonlinear friction model is designed by adaptive control law and adaptive backstepping control method.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.40 no.12
• /
• pp.1067-1076
• /
• 2016

This paper describes the development of a hybrid-powered wheelchair (HPW) for the elderly. The proposed HPW has novel mechanical and control features compared with conventional powered wheelchairs. An ergonomic back-braking mechanism was designed in order to stop the wheels easily. In terms of control features, the HPW remarkably reduces the muscle power required by combining various assistive functions, such as wheel torque assistance, friction/inertia compensation, gravity compensation, and the one-hand driving algorithm. For wheel torque assistance, strain gauges were attached to the hand-rim in order to measure the wheel torque applied by a human. Gyroscopes and an accelerometer were attached to the wheel and chair respectively for friction and inertia compensation. An inclinometer was attached for gravity compensation and the one-hand driving algorithm was included for patients who can only use one hand. The one-hand driving algorithm controls the angular velocity of the uncontrolled wheel by using a gyroscope and pressure sensors attached to the bottom of the seat. Finally, the performance of the proposed motion assisted algorithm was verified through various experiments.

• Proceedings of the KIEE Conference
• /
• 2003.07e
• /
• pp.103-105
• /
• 2003

본 논문에서는 이동로봇의 마찰력 보상을 위해 퍼지 외란 관측자를 설계한다. 이동로봇은 주행 바닥면에 따라 주행 특성이 달라질 수 있다. 주행 중 발생하는 마찰력은 비선형적인 특성을 가지므로 이에 검출할 수 있는 퍼지 관측기를 설계하도록 한다. 설계된 퍼지 관측기를 적용함으로써 주행 바닥 면의 상태에 따라 발생하는 마찰력의 영향을 최소화시킴으로써 주행 특성을 효과적으로 개선시킬 수 있다.