Presents the detailed algorithm established for determination of workspace for a 3-DOF coordinate measuring machine using parallel link mechanism by constructing the inverse kinematic model first and then reviewing th...Presents the detailed algorithm established for determination of workspace for a 3-DOF coordinate measuring machine using parallel link mechanism by constructing the inverse kinematic model first and then reviewing the physical and kinematical constraints from the structural characteristics of the parallel link mechanism, and discusses the actual geometries of workspace and the factors having effect on workspace through computer simulation thereby providing necessary theoretical basis for the research and development of coordinate measuring machines using parallel link mechanism.展开更多
The object of study is about dynamic modeling and control for a 2degree-of-freedom (DOF) planar parallel mechanism (PM) with flexible links. The kinematic anddynamic equations are established according to the characte...The object of study is about dynamic modeling and control for a 2degree-of-freedom (DOF) planar parallel mechanism (PM) with flexible links. The kinematic anddynamic equations are established according to the characteristics of mixed rigid and flexiblestructure. By using the singular perturbation approach (SPA), the model of the mechanism can beseparated into slow and fast subsystems. Based on the feedback linearization theory and inputshaping technique, the large scale rigid motion controller and the flexible link vibrationcontroller can be designed separately to achieve fast and accurate positioning of the PM.展开更多
The determination of virtual constraints is always one of the key and difficult problems in traditional mobility calculation. To make mobility calculation simple, considering avoiding virtual constraints, some new for...The determination of virtual constraints is always one of the key and difficult problems in traditional mobility calculation. To make mobility calculation simple, considering avoiding virtual constraints, some new formulae have been presented, however these formulae can hardly intuitively reflect general link group＇s restrictions on output member and its influences on independence of output parameters, which is premise to the judgment of the properties of mobility. Towards the problem to reveal the intrinsic relationship between the degree of freedom（DOF） of a mechanism, the link group, and the dimension of output parameters, also to avoid determination of virtual constraint, based on the new concepts of the ＂DOF of general link group＂ and ＂node parameters＂, a new formula in the calculation of the mobility of mechanisms is presented that is expressed with DOFs of the general link groups and rank of motion parameters of base point of the output link. It is named GOM（mobility of groups and output parameter） formula. On the basis of new concepts of＂effective parameters＂ and ＂invalid parameters＂, a rule is put forward for solving the DOF of mechanisms with invalid parameters by GOM formula, that is, the base point parameters are the subset of effective parameters of link group. Thereafter, several examples are enumerated and the results coincide with the prototype data, which proves the validity of the proposed formula. Meanwhile, it is obtained that the necessary and sufficient condition for the judgment of output parameters independence is that each of the DOF of the link group is not less than zero. The proposed formula which is simple in calculation provides theoretical basis for the judgment of independence of output parameters and provides references for type synthesis of novel parallel mechanisms with independence requirements of their output parameters.展开更多
介绍了一种基于AC-link技术的并联谐振高压电源的拓扑电路,该结构结合准谐振的工作模式能够实现高功率因数和高效率;采用了基于状态平面图对并联谐振电路的分析方法,该方法相比传统的基波等效分析法具有求解简单、直观、精确和负载适用...介绍了一种基于AC-link技术的并联谐振高压电源的拓扑电路,该结构结合准谐振的工作模式能够实现高功率因数和高效率;采用了基于状态平面图对并联谐振电路的分析方法,该方法相比传统的基波等效分析法具有求解简单、直观、精确和负载适用范围大的特点,并给出了相应推导过程;给出了输出电压为25 k V,电流为1 A的变换器的分析和谐振参数设计。最后进行了仿真,仿真结果表明,基于高频交流链接并联谐振拓扑和基于状态平面图法的控制能够稳定输出电压(<1%),实现零电流开关,三相输入电流谐波较低(THD<12.5%)与三相电压基本同相位,功率因数为0.99。展开更多
直流变压器是互联网数据中心(Internet Data Center,IDC)配电系统的重要单元,其技术水平影响着整个IDC配电系统的运营水平。以逻辑链路控制(Logical Link Control,LLC)谐振变换器为基础单元模块,以输入串联、输出并联为拓扑结构,设计了...直流变压器是互联网数据中心(Internet Data Center,IDC)配电系统的重要单元,其技术水平影响着整个IDC配电系统的运营水平。以逻辑链路控制(Logical Link Control,LLC)谐振变换器为基础单元模块,以输入串联、输出并联为拓扑结构,设计了一款基于IDC配电系统的直流变压器。首先介绍了直流变压器系统的拓扑结构,并分析了其均压均流特性;其次又提出了一种三环控制策略,主要对直流变压器系统进行均压均流控制,该策略可以使系统稳定输出额定电压,并使系统具有良好的均压均流效果;最后设计一款10 kV/400 V的直流变压器系统,实验表明该系统运行效果良好,具有较高的稳定性和调节能力。展开更多
文摘Presents the detailed algorithm established for determination of workspace for a 3-DOF coordinate measuring machine using parallel link mechanism by constructing the inverse kinematic model first and then reviewing the physical and kinematical constraints from the structural characteristics of the parallel link mechanism, and discusses the actual geometries of workspace and the factors having effect on workspace through computer simulation thereby providing necessary theoretical basis for the research and development of coordinate measuring machines using parallel link mechanism.
基金This project is supported by National Natural Science Foundation of China (No.50390064, No.50375099) Doctorate Foundation of Ministry of Education of China(No.20020248048).
文摘The object of study is about dynamic modeling and control for a 2degree-of-freedom (DOF) planar parallel mechanism (PM) with flexible links. The kinematic anddynamic equations are established according to the characteristics of mixed rigid and flexiblestructure. By using the singular perturbation approach (SPA), the model of the mechanism can beseparated into slow and fast subsystems. Based on the feedback linearization theory and inputshaping technique, the large scale rigid motion controller and the flexible link vibrationcontroller can be designed separately to achieve fast and accurate positioning of the PM.
基金supported by National Natural Science Foundation of China(Grant Nos.51275438,51005195)Hebei Provincial Natural Science Foundation of(Grant No.E2011203214)Development Program of Qinhuangdao City,China(Grant No.201101A069)
文摘The determination of virtual constraints is always one of the key and difficult problems in traditional mobility calculation. To make mobility calculation simple, considering avoiding virtual constraints, some new formulae have been presented, however these formulae can hardly intuitively reflect general link group＇s restrictions on output member and its influences on independence of output parameters, which is premise to the judgment of the properties of mobility. Towards the problem to reveal the intrinsic relationship between the degree of freedom（DOF） of a mechanism, the link group, and the dimension of output parameters, also to avoid determination of virtual constraint, based on the new concepts of the ＂DOF of general link group＂ and ＂node parameters＂, a new formula in the calculation of the mobility of mechanisms is presented that is expressed with DOFs of the general link groups and rank of motion parameters of base point of the output link. It is named GOM（mobility of groups and output parameter） formula. On the basis of new concepts of＂effective parameters＂ and ＂invalid parameters＂, a rule is put forward for solving the DOF of mechanisms with invalid parameters by GOM formula, that is, the base point parameters are the subset of effective parameters of link group. Thereafter, several examples are enumerated and the results coincide with the prototype data, which proves the validity of the proposed formula. Meanwhile, it is obtained that the necessary and sufficient condition for the judgment of output parameters independence is that each of the DOF of the link group is not less than zero. The proposed formula which is simple in calculation provides theoretical basis for the judgment of independence of output parameters and provides references for type synthesis of novel parallel mechanisms with independence requirements of their output parameters.
文摘介绍了一种基于AC-link技术的并联谐振高压电源的拓扑电路,该结构结合准谐振的工作模式能够实现高功率因数和高效率;采用了基于状态平面图对并联谐振电路的分析方法,该方法相比传统的基波等效分析法具有求解简单、直观、精确和负载适用范围大的特点,并给出了相应推导过程;给出了输出电压为25 k V,电流为1 A的变换器的分析和谐振参数设计。最后进行了仿真,仿真结果表明,基于高频交流链接并联谐振拓扑和基于状态平面图法的控制能够稳定输出电压(<1%),实现零电流开关,三相输入电流谐波较低(THD<12.5%)与三相电压基本同相位,功率因数为0.99。
文摘直流变压器是互联网数据中心(Internet Data Center,IDC)配电系统的重要单元,其技术水平影响着整个IDC配电系统的运营水平。以逻辑链路控制(Logical Link Control,LLC)谐振变换器为基础单元模块,以输入串联、输出并联为拓扑结构,设计了一款基于IDC配电系统的直流变压器。首先介绍了直流变压器系统的拓扑结构,并分析了其均压均流特性;其次又提出了一种三环控制策略,主要对直流变压器系统进行均压均流控制,该策略可以使系统稳定输出额定电压,并使系统具有良好的均压均流效果;最后设计一款10 kV/400 V的直流变压器系统,实验表明该系统运行效果良好,具有较高的稳定性和调节能力。
