Recently novel mechanisms with compact size and without many mechanical elements such as bearing are strongly required for medical devices such as surgical operation devices. This paper describes analysis and synthesi...Recently novel mechanisms with compact size and without many mechanical elements such as bearing are strongly required for medical devices such as surgical operation devices. This paper describes analysis and synthesis of elastic link mechanisms of a single spring beam which can be manufactured by NC coiling machines. These mechanisms are expected as disposable micro forceps. Smooth Curvature Model（SCM） with 3rd order Legendre polynomial curvature functions is applied to calculate large deformation of a curved cantilever beam by taking account of the balance between external and internal elastic forces and moments. SCM is then extended to analyze large deformation of a closed-loop curved elastic beam which is composed of multiple free curved beams. A closed-loop elastic link is divided into two free curved cantilever beams each of which is assumed as serially connected free curved cantilever beams described with SCM. The sets of coefficients of Legendre polynomials of SCM in all free curved cantilever beams are determined by taking account of the force and moment balance at connecting point where external input force is applied. The sets of coefficients of Legendre polynomials of a nonleaded closed-loop elastic link are optimized to design a link mechanism which can generate specified output motion due to input force applied at the assumed dividing point. For example, two planar micro grippers with a single pulling input force are analyzed and designed. The elastic deformation analyzed with proposed method agrees very well with that calculated with FEM. The designed micro gripper can generate the desired pinching motion. The proposed method can contribute to design compact and simple elastic mechanisms without high calculation costs.展开更多
In this paper,a long stroke moving secondary permanent magnet linear eddy current brake is proposed.Without exciting coils,the permanent magnet eddy current brake possesses the advantage of saving copper and better re...In this paper,a long stroke moving secondary permanent magnet linear eddy current brake is proposed.Without exciting coils,the permanent magnet eddy current brake possesses the advantage of saving copper and better reliability.The topology and operating principle are presented.The mathematical model was derived with the layer theory.The braking force characteristic was analyzed using the finite element method.The structural parameters of the long stroke moving secondary permanent magnet linear eddy current brake were studied by referring the design progress of the other types of eddy current brakes.Finally,a prototype of long stroke moving secondary permanent magnet linear eddy current brake was built and tested,and the experimental result verifies the correctness of the above analysis.展开更多
In order to further analyze the influence of clearance on the kinematic performance of spatial linkage weft insertion mechanism,it is necessary to study the dynamic characteristics of contact impact force model with t...In order to further analyze the influence of clearance on the kinematic performance of spatial linkage weft insertion mechanism,it is necessary to study the dynamic characteristics of contact impact force model with the variable stiffness and damping coefficient.Firstly,the parameters in the output process of the system are solved by describing of the flexible joint clearance.Then,based on Lankarani-Nikravesh contact force model,the contact impact stiffness and damping coefficient is modified from fixed values to time-varying coefficients.The dynamic model of spatial linkage weft insertion mechanism with modified clearance is established by Lagrange method,and the dynamic characteristics of the system are calculated.The results show that the joint clearance can directly affect the output performance of the mechanism.With the increase of the clearance value,the curve fluctuations of acceleration,driving torque and collision force are obvious,and it will be further intensified with the increase of spindle speed,which greatly affects the stability of mechanism and fabric quality.Finally,the virtual prototype is established by the SolidWorks software and simulated by the ADAMS software.The simulation results are compared with the numerical results,which verifies the accuracy of the modeling method in this paper.展开更多
为了提高电动汽车制动能量回收效率,对电动汽车制动能量再生系统及机电制动力分配控制策略进行了研究。以制动强度为依据划分制动模式,提出了以电子制动力分配(Electronic Brake force Distribution,EBD)来分配前、后轴制动力的电动机...为了提高电动汽车制动能量回收效率,对电动汽车制动能量再生系统及机电制动力分配控制策略进行了研究。以制动强度为依据划分制动模式,提出了以电子制动力分配(Electronic Brake force Distribution,EBD)来分配前、后轴制动力的电动机制动与机械制动的协调控制策略方法,建立了相应的再生制动系统前、后轴制动力分配控制策略模型,并且对控制模型进行了仿真分析。仿真结果表明,提出的控制策略方法不仅可以提高制动能量回收的效率,还可以有效防止车轮在低附着路面上抱死,保证了车辆的稳定性与安全性。展开更多
文摘Recently novel mechanisms with compact size and without many mechanical elements such as bearing are strongly required for medical devices such as surgical operation devices. This paper describes analysis and synthesis of elastic link mechanisms of a single spring beam which can be manufactured by NC coiling machines. These mechanisms are expected as disposable micro forceps. Smooth Curvature Model（SCM） with 3rd order Legendre polynomial curvature functions is applied to calculate large deformation of a curved cantilever beam by taking account of the balance between external and internal elastic forces and moments. SCM is then extended to analyze large deformation of a closed-loop curved elastic beam which is composed of multiple free curved beams. A closed-loop elastic link is divided into two free curved cantilever beams each of which is assumed as serially connected free curved cantilever beams described with SCM. The sets of coefficients of Legendre polynomials of SCM in all free curved cantilever beams are determined by taking account of the force and moment balance at connecting point where external input force is applied. The sets of coefficients of Legendre polynomials of a nonleaded closed-loop elastic link are optimized to design a link mechanism which can generate specified output motion due to input force applied at the assumed dividing point. For example, two planar micro grippers with a single pulling input force are analyzed and designed. The elastic deformation analyzed with proposed method agrees very well with that calculated with FEM. The designed micro gripper can generate the desired pinching motion. The proposed method can contribute to design compact and simple elastic mechanisms without high calculation costs.
基金This work was supported in part by the National Natural Science Foundation of China under Grant 51877051,the Research and Development Project of Scientific and Technological Achievements in Provincial Universities of Heilongjiang Education Department under Grant TSTAU-C2018014.
文摘In this paper,a long stroke moving secondary permanent magnet linear eddy current brake is proposed.Without exciting coils,the permanent magnet eddy current brake possesses the advantage of saving copper and better reliability.The topology and operating principle are presented.The mathematical model was derived with the layer theory.The braking force characteristic was analyzed using the finite element method.The structural parameters of the long stroke moving secondary permanent magnet linear eddy current brake were studied by referring the design progress of the other types of eddy current brakes.Finally,a prototype of long stroke moving secondary permanent magnet linear eddy current brake was built and tested,and the experimental result verifies the correctness of the above analysis.
基金National Natural Science Foundation of China(No.11402186)Innovative Research Team in University of Tianjin,China(No.TD13-5037)Natural Science Foundation of Tianjin,China(Nos.14JCQNJC05600 and 18JCQNJC05300)。
文摘In order to further analyze the influence of clearance on the kinematic performance of spatial linkage weft insertion mechanism,it is necessary to study the dynamic characteristics of contact impact force model with the variable stiffness and damping coefficient.Firstly,the parameters in the output process of the system are solved by describing of the flexible joint clearance.Then,based on Lankarani-Nikravesh contact force model,the contact impact stiffness and damping coefficient is modified from fixed values to time-varying coefficients.The dynamic model of spatial linkage weft insertion mechanism with modified clearance is established by Lagrange method,and the dynamic characteristics of the system are calculated.The results show that the joint clearance can directly affect the output performance of the mechanism.With the increase of the clearance value,the curve fluctuations of acceleration,driving torque and collision force are obvious,and it will be further intensified with the increase of spindle speed,which greatly affects the stability of mechanism and fabric quality.Finally,the virtual prototype is established by the SolidWorks software and simulated by the ADAMS software.The simulation results are compared with the numerical results,which verifies the accuracy of the modeling method in this paper.
文摘为了提高电动汽车制动能量回收效率,对电动汽车制动能量再生系统及机电制动力分配控制策略进行了研究。以制动强度为依据划分制动模式,提出了以电子制动力分配(Electronic Brake force Distribution,EBD)来分配前、后轴制动力的电动机制动与机械制动的协调控制策略方法,建立了相应的再生制动系统前、后轴制动力分配控制策略模型,并且对控制模型进行了仿真分析。仿真结果表明,提出的控制策略方法不仅可以提高制动能量回收的效率,还可以有效防止车轮在低附着路面上抱死,保证了车辆的稳定性与安全性。
