• Structural Engineering and Mechanics
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• v.82 no.2
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• pp.205-224
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• 2022

This paper presents a refined finite element formulation for nonlinear static and dynamic analysis of sliding cable structures, overcoming the limitation of the existing approaches that neglect or approximate the friction, pulley dimension, temperature and geometric nonlinearity. A new family of elements with the same framework is proposed, consisting of the cable-pulley (CP) elements considering sliding friction, and the non-sliding cable-pulley (NSCP) elements considering static friction. Thereafter, the complete procedure of static and dynamic analysis using the proposed elements is developed, with the capability of accurately dealing with the friction at each pulley. Several examples are utilized to verify the validity and accuracy of the proposed elements and analysis strategy, and investigate the frictional, thermal and pulley-dimension effects as well. The numerical examples show that the results obtained in this work are in good accordance with the existing works when using the same approximations of friction, pulley dimension and temperature. By avoiding the approximations, the proposed formulation can be effectively adopted in predicting the more precise nonlinear responses of sliding cable structures.

• International Journal of Naval Architecture and Ocean Engineering
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• v.13 no.1
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• pp.746-757
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• 2021

To investigate the mechanism of friction-induced vibration and noise of ship water lubricated stern bearings, a two-degree-of-freedom (2-DOF) nonlinear self-excited vibration model is established. The novelty of this work lies in the detailed analysis of influence of different parameters on the stability and nonlinear vibration characteristics of the system, which provides a theoretical basis for the various friction vibration and noise phenomenon and has a very important directive meaning for low noise design of water lubricated stern bearings. The results reveal that the change of any parameter, such as rotating speed of shaft, contact pressure, friction coefficient, system damping and stiffness, has an important influence on the stability and nonlinear response of the system. The vibration amplitudes of the system increase as (a) rotating speed of shaft, contact pressure, and the ratio of static friction coefficient to dynamic friction coefficient increase and (b) the transmission damping between motor and shaft decreases. The frequency spectrum of the system is modulated by the first mode natural frequency, which is continuous multi-harmonics of the first mode natural frequency. The response of the system presents a quasi-periodic motion.

• International Journal of Precision Engineering and Manufacturing
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• v.4 no.5
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• pp.5-14
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• 2003

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 fer effects of friction. The conventional SMC method often shows poor tracking performance in high-precision position tracking application since it cannot completely compensate for the friction effect below a certain precision level. Thus to improve the precise position tracking performance, we propose the SMC method combined with the disturbance observer having tunable transient performance. Then this control scheme has the high precise tracking peformance as well as a good transient response when it is compared with the conventional SMC method and the similar types of observers, The experiment on the XY ball-screw drive system with the nonlinear dynamic friction confirms the feasibility of the proposed control scheme.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.19 no.2
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• pp.241-250
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• 2010

A recurrent adaptive model-free intelligent control with a friction estimation law is proposed to enhance the positioning performance of the mover in PMLSM system. For the PMLSM with nonlinear friction and uncertainty, an adaptive recurrent fuzzy neural network(ARFNN) and compensated control law in $H_{\infty}$ performance criterion are designed to mimic a perfect control law and compensate the approximated error between ideal controller and ARFNN. Combined with friction observer to estimate nonlinear friction parameters of the LuGre model, on-line adaptive laws of the controller and observer are derived based on the Lyapunov stability criterion. To analyze the effectiveness our control scheme, some simulations for the PMLSM with nonlinear friction and uncertainty were executed.

• Journal of the Korean Society for Precision Engineering
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• v.14 no.4
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• pp.88-96
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• 1997

This paper suggests a new non-linear friction compensation for digital control systems. This control adopts a hysteresis nonlinear element which can introduce the phase lead of the control system to compensate the phase delay comes from the inherent time delay of a digital control. A proper Lyapunov function is selected and the Lyapunov direct method is used to prove the asymptotic stability of the suggested control.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.11a
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• pp.987-993
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• 1996

This report suggests a new non-linear friction compensation for digital control systems. This control adopts a hysteric nonlinear clement which can introduce the phase lead of the control system to compensate the phase delay comes from the inherent time delay of a digital control. The Lyapunov direct method is used to prove the asymtotic stability of the suggested control, and the stability and the effectiveness are verified analytically and experimentally on a single axis servo driving system.

• Journal of the Korean Society for Precision Engineering
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• v.25 no.12
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• pp.89-99
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• 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.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.10a
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• pp.250-251
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• 2014

This paper investigates the stick-slip phenomena on spinning shaft. The modeling of the shaft is considered only torsional direction with nonlinear friction. The friction is adopted a negative friction-velocity slope. Based on the model, a nonlinear equation of motion is derived and analyze the stick-slip phenomena. In order to analyze the time dependent response, the nonlinear formulations are numerically solved by nonlinear Newmark method. The numerical results reveal the stick-slip phenomena on the spinning shaft system.

• Transactions on Control, Automation and Systems Engineering
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• v.4 no.4
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• pp.311-318
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• 2002

Two adaptive nonlinear friction compensation schemes are proposed for second-order nonlinear mechanical systems with a partially known nonlinear dynamic friction model to achieve asymptotic position and velocity tracking. The first scheme has auxiliary filtered states so that a simple open-loop observer can be used. The second one has a dual-observer structure to estimate two different nonlinear aspects of the friction state. Conditions for the parameter estimates to converge to the true parameter values are presented. Simulation results are utilized to show control performance and to demonstrate the convergence of the parameter estimates to their true values.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.54 no.7
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• pp.428-436
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• 2005

In this paper, we introduce an adaptive control method to improve the position accuracy and reduce nonlinear friction effects for the linear motion servo system with the nonlinear friction. The considered system plant included not only the variation of the mass of mover but also the friction change by the normal force. We also designed an adaptive controller with the mass estimator and the compensator by observing the variation of normal force. The effectiveness and system performances for the proposed control method in this paper show to improve than other control methods through numerical simulations.