The contact stiffness and the error analysis have an important effect on the manufacture and the optimization of Ball Linear Guide Feed Unit( BLGFU). In order to analyze the contact stiffness and linear errors or angl...The contact stiffness and the error analysis have an important effect on the manufacture and the optimization of Ball Linear Guide Feed Unit( BLGFU). In order to analyze the contact stiffness and linear errors or angle errors of BLGFU,in this paper,the contact stress and deformation mechanics between the ball and rail is analyzed. Based on Hertz theory of contact and theory of the multi-body system,a model of the contact stiffness considering the changes in contact angle is established. With the increasing of the external load,the varying trend of the contact deformation can be obtained. Therefore, the motion accuracy degradation of the BLGFU can be analyzed. By using a special experimental device and test system of the rolling linear guide worktable,the horizontal contact stiffness and the vertical linear stiffness are obtained,respectively. By comparing the contact stiffness of the experiment dates and the simulation results,the variation tendency of two curves is consisted and the difference between the measured values and the theoretical values is less than 18%. It is obvious that the model of the contact stiffness considering changes of contact angle has accuracy and feasibility. Thus,while external force point locating at different positions; the contact stiffness and the accuracy analysis of the BLGFU are proved validity by simulations.展开更多
Porous Ti with low modulus,excellent bio-corrosion resistance,biocompatibility,and antibacterial activity is highly pursued as advanced implant materials.In this work,a new approach to prepare micron porous structures...Porous Ti with low modulus,excellent bio-corrosion resistance,biocompatibility,and antibacterial activity is highly pursued as advanced implant materials.In this work,a new approach to prepare micron porous structures on the surface layer of a grade 2 commercially-pure Ti(TA2)was proposed,which utilized a simple vacuum wetting process of pure Ag on the surface of TA2.The microstructure,corrosion resistance,biocompatibility,mechanical properties,antibacterial ability,and formation mechanism of the asfabricated porous Ti were studied.The results show that the pores(with average pore sizes of 0.5-5μm)are distributed on the surface layer of the TA2 with a depth of~10μm.In particular,a large number of silver nanoparticles(Ag NPs)form which are dispersed on the porous structures.The formation mechanisms of the porous structures and Ag NPs were elucidated,suggesting that the volatilization/sublimation of Ag in TA2 is crucial.The porous Ti possesses excellent bio-corrosion resistance,surface wettability,biocompatibility,antibacterial activity,and a relatively low elastic modulus of 40-55 GPa,which may have a promising future in the field of orthopedic implants.This work also provides a novel idea for the development of advanced porous Ti materials for orthopedic-related basic research and biomedical applications.展开更多
In the era of intelligent revolution,pneumatic artificial muscle(PAM)actuators have gained significance in robotics,particularly for tasks demanding high safety and flexibility.Despite their inherent flexibility,PAMs ...In the era of intelligent revolution,pneumatic artificial muscle(PAM)actuators have gained significance in robotics,particularly for tasks demanding high safety and flexibility.Despite their inherent flexibility,PAMs encounter challenges in practical applications because of their complex material properties,including hysteresis,nonlinearity,and low response frequencies,which hinder precise modeling and motion control,limiting their widespread adoption.This study focuses on fuzzy logic dynamic surface control(DSC)for PAMs,addressing full-state constraints and unknown disturbances.We propose an improved neural DSC method,combining enhanced DSC techniques with fuzzy logic system approximation and parameter minimization for PAM systems.The introduction of a novel barrier Lyapunov function during system design effectively resolves full-state constraint issues.A key feature of this control approach is its single online estimation parameter update while maintaining stability characteristics akin to the conventional backstepping method.Importantly,it ensures constraint adherence even in the presence of disturbances.Lyapunov stability analysis confirms signal boundedness within the closed-loop system.Experimental results validate the algorithm’s effectiveness in enhancing control precision and response speed.展开更多
基金Sponsored by the National Natural Science Foundation of China(Grant Nos.51505012 and 51575014)the Natural Science Foundation of Beijing(Grant No.KZ201410005010)+2 种基金the Important National Science&Technology Specific Projects of China(Grant No.2012ZX04010021-001-004)the China Postdoctoral Science Foundation Funded Project(Grant No.2016M591033)the Beijing Postdoctoral Research Foundation(Grant No.2015ZZ-13)
文摘The contact stiffness and the error analysis have an important effect on the manufacture and the optimization of Ball Linear Guide Feed Unit( BLGFU). In order to analyze the contact stiffness and linear errors or angle errors of BLGFU,in this paper,the contact stress and deformation mechanics between the ball and rail is analyzed. Based on Hertz theory of contact and theory of the multi-body system,a model of the contact stiffness considering the changes in contact angle is established. With the increasing of the external load,the varying trend of the contact deformation can be obtained. Therefore, the motion accuracy degradation of the BLGFU can be analyzed. By using a special experimental device and test system of the rolling linear guide worktable,the horizontal contact stiffness and the vertical linear stiffness are obtained,respectively. By comparing the contact stiffness of the experiment dates and the simulation results,the variation tendency of two curves is consisted and the difference between the measured values and the theoretical values is less than 18%. It is obvious that the model of the contact stiffness considering changes of contact angle has accuracy and feasibility. Thus,while external force point locating at different positions; the contact stiffness and the accuracy analysis of the BLGFU are proved validity by simulations.
基金sponsored by the National Natural Science Foundation of China(Nos.52171036,52065043,and 51971108)the Central Guidance on Local:Construction of regional innovation system-Cross Regional R&D cooperation projects(No.20221ZDH04054)the Interdisciplinary Innovation Fund of Natural Science,Nanchang Universit
文摘Porous Ti with low modulus,excellent bio-corrosion resistance,biocompatibility,and antibacterial activity is highly pursued as advanced implant materials.In this work,a new approach to prepare micron porous structures on the surface layer of a grade 2 commercially-pure Ti(TA2)was proposed,which utilized a simple vacuum wetting process of pure Ag on the surface of TA2.The microstructure,corrosion resistance,biocompatibility,mechanical properties,antibacterial ability,and formation mechanism of the asfabricated porous Ti were studied.The results show that the pores(with average pore sizes of 0.5-5μm)are distributed on the surface layer of the TA2 with a depth of~10μm.In particular,a large number of silver nanoparticles(Ag NPs)form which are dispersed on the porous structures.The formation mechanisms of the porous structures and Ag NPs were elucidated,suggesting that the volatilization/sublimation of Ag in TA2 is crucial.The porous Ti possesses excellent bio-corrosion resistance,surface wettability,biocompatibility,antibacterial activity,and a relatively low elastic modulus of 40-55 GPa,which may have a promising future in the field of orthopedic implants.This work also provides a novel idea for the development of advanced porous Ti materials for orthopedic-related basic research and biomedical applications.
基金supported by the National Key Research and Development Program of China(Grant No.2022YFF0708903)in part by the Ningbo Key Technology Research and Development Program of China(Grant No.2023Z018)+1 种基金in part by the National Natural Science Foundation of China(Grant No.52275043)in part by the Zhejiang Lab Open Research Project of China(Grant No.121001-AB2212).
文摘In the era of intelligent revolution,pneumatic artificial muscle(PAM)actuators have gained significance in robotics,particularly for tasks demanding high safety and flexibility.Despite their inherent flexibility,PAMs encounter challenges in practical applications because of their complex material properties,including hysteresis,nonlinearity,and low response frequencies,which hinder precise modeling and motion control,limiting their widespread adoption.This study focuses on fuzzy logic dynamic surface control(DSC)for PAMs,addressing full-state constraints and unknown disturbances.We propose an improved neural DSC method,combining enhanced DSC techniques with fuzzy logic system approximation and parameter minimization for PAM systems.The introduction of a novel barrier Lyapunov function during system design effectively resolves full-state constraint issues.A key feature of this control approach is its single online estimation parameter update while maintaining stability characteristics akin to the conventional backstepping method.Importantly,it ensures constraint adherence even in the presence of disturbances.Lyapunov stability analysis confirms signal boundedness within the closed-loop system.Experimental results validate the algorithm’s effectiveness in enhancing control precision and response speed.
