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The Rolling Wheel Equations without Magic: A Combined Slip-stiction Approach by the Udwadia-Kalaba Formulation with Constraints Relaxation for a Smooth Simulation

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Journal of Transportation Technologies 2021年第3期11卷 378-389页

作者： Bukoko Ikoki KDYNAMICS Logiciel Inc. Sherbrooke Canada

The Udwadia-Kalaba formulation is proposed to model the dynamics of the rolling wheel. A unified approach that addresses both the slip and the stiction in the contact section is considered. Purely rolling constraints are associated with stiction and are suitably lifted as slip occurs. An extended formulation for the Uwadia-Kalaba equations of motion is introduced for that matter. It resorts to the weighted minimum norm and the weighted semi-least-squares solutions of the constraints equations. This not only allows a bias on constraints, by an appropriate description of weight functions based on friction, it also leads to a smooth activation or deactivation of selected constraints without rewriting the equations of motion or upsetting their numerical integration.

关键词： Rolling Wheel Friction stiction Slip Constraints Relaxation

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Contact mechanics in flexural MEMS stiction

Contact mechanics in flexural MEMS stiction

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第十二届全国物理力学学术会议

作者： Yin Zhang Ya-Pu Zhao The State Key Laboratory of Nonlinear Mechanics Institute of MechanicsChinese Academy of Sciences

A variational method using the principle of virtual work(PVW) is presented to formulate the problem of the microcantilever *** with the Rayleigh-Ritz method using the arc-shaped or S-shaped deflection,which prescribes the boundary conditions and thus the deflection shape of a stuck cantilever beam,the new method uses the matching conditions and constraint condition derived from PVW and minimization of the system free energy to describe the boundary conditions at the contact separation *** transition of the beam deflection from an arc-shape-like one to an S-shape-like one with the increase of the beam length is shown by the new ***(real) beam deflection given by this new model deviates more or less from either an arc-shape or an S-shape,which has significant impact on the interpretation of experimental *** arc-shaped or S-shaped deflection assumption ignores the beam bending energy inside the contact area and the elastic energy due to the beam/substrate contact,which is inappropriate as shown by this ***,the arc-shaped or S-shaped deflection only approximately describes the deflection shape of a stuck beam with zero external load and obviously,the external load changes the beam *** Rayleigh-Ritz method using the arc-shaped or S-shaped deflection assumption in essence can only be used to tell approximately whether stiction occurs or *** than assuming a certain deflection shape and by incorporating the external load, the new method offers a more general and accurate study not only on the microcantilever beam stiction but also on its de-adherence.

关键词： stiction MEMS arc-shape S-shape adhesion

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An Improved PI Controller for stiction Compensation of Control Valves in Process Industry

An Improved PI Controller for Stiction Compensation of Contr...

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第43届中国控制会议

作者： Dong Yang Xun Lang Jiande Wu Yumin Lang Lei Xie Hongye Su Department of Electronic Engineering School of Information Yunnan University Yunnan Key Laboratory of Intelligent Systems and Computing Yunnan University State Key Laboratory of Industrial Control Technology Zhejiang University

In the process industry, limit cycles are mostly induced by stiction-related nonlinearity in control valves, severely deteriorating control loop performance. Such problem highlights the importance of compensating for oscillations due to valve stiction. To this end, this work introduces an improved PI controller(IPIC) for stiction compensation, which retains the advantages of the traditional PI controller with fewer adjustment parameters. The enhancement involves nonlinear variation of the integral gain based on instantaneous error. Additionally, a differential evolution algorithm is utilized for controller *** to state-of-the-art methods in setpoint tracking, disturbance rejection, and robustness to parameter uncertainties, the proposed approach exhibits superior performance.

关键词： stiction Limit Cycle Nonlinear PI controller Differential Evolution Algorithm

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Application in prestiction friction compensation for angular velocity loop of inertially stabilized platforms

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Chinese Journal of Aeronautics 2014年第3期27卷 655-662页

作者： Zhang Zhiyong Li Zhiqiang Zhou Qingkun Zhang Lianchao Fan Dapeng College of Mechatronic Engineering and Automation National University of Defense Technology

Abstract To overcome the influence of the nonlinear friction on the gimbaled servo-system of an inertial stabilized platforms （ISPs） with DC motor direct-drive, the methods of modeling and compensation of the nonlinear friction are proposed. Firstly, the inapplicability of LuGre model when trying to interpret the backward angular displacement in the prestiction regime is observed experimentally and the reason is deduced theoretically. Then, based on the dynamic model of direct-drive ISPs, a modified LuGre model is proposed to describe the characteristic of the friction in the prestiction regime. Furthermore, the state switch condition of the three friction regimes including presliding, gross sliding and prestiction is presented. Finally, a composite compensation controller including a nonlinear friction observer and a feedforward compensator based on the novel LuGre model is designed to restrain the nonlinear friction and to improve the control precision. Experimental results indicate that compared with those of the conventional proportion-integrationdifferentiation （PID） control method and the PID plus LuGre model-based friction compensation method, the dwell-time has decreased from 0.2 s to almost 0 s, the position error decreased to 86.7% and the peak-to-peak value of position error decreased to 80% after the novel compensation controller is added. It concludes that the composite compensation controller can greatly improve the control precision of the dynamic sealed ISPs.

关键词： Closed loop control systems Friction compensation Inertially stabilized platforms Prestiction stiction

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Capillary Interactions between a Probe Tip and a Nanoparticle

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Chinese Physics Letters 2008年第5期25卷 1795-1798页

作者：孙立宁王乐锋荣伟彬 State Key Laboratory of Robotics and System Harbin Institute of Technology Harbin 150080

To understand capillary interactions between probe tips and nanoparticles under ambient conditions, a theoretical model of capillary forces between them is developed based on the geometric relations. It is found that the contribution of surface tension force to the total capillary force attains to similar order of magnitude as the capillary pressure force in many cases. It is also shown that the tip shape and the radial distance of the meniscus have great influence on the capillary force. The capillary force decreases with the increasing separation distances, and the variance of the contact angles may change the magnitudes of capillary forces several times at large radial distances. The applicability of the symmetric meniscus approximation is discussed.

关键词： ATOMIC-FORCE MICROSCOPE SURFACE NANOMANIPULATION stiction MEMS

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