On seeking new plane-symmetric six-bars

We survey the collection of established plane-symmetric six-revolute linkages in order to select forms for which it is likely that new solutions might be found. Having done so, we use closure equation algebra to determine existence criteria for such possible solutions, but find that there can be none, apart from special cases of those already known. We are able, however, to extend the analysis to isolate four new plane-symmetric six-bars containing screw joints. It becomes pertinent in the proceedings to indicate some shortcomings in earlier works.     

Overconstrained 5-bars with parallel adjacent joint axes — I Method of Analysis

Almost all overconstrained spatial 4-bar linkages have now been systematically isolated. Several categories of 5- and 6-bar linkages have also been determined, but without reference to any exhaustive form of analysis. In this Part of the present paper, a method will be set up to allow a major attempt in solving the 5-bar linkage problem. Included in the technique is a new procedure for simplifying the analysis of linkages which contain screw joints, a considerable stumbling-block for earlier researchers.     

Mobility of the Myard 5R Linkage Involved in ＂Gogu Problem＂

Since the traditional Grübler-Kutzbach criterion fails in many overconstrained mechanisms, developing a general mobility formula is a hot topic lasting for more than 150 years in mechanisms. GOGU systematically investigated various mobility methods, and pointed that the methods were not fit for two kinds of paradoxical overconstrained mechanisms. The mobility on the two kinds of mechanisms in "Gogu problem", and has developed into a systematic mobility methodology. Myard 5R linkage is one of the single-loop mechanisms involved in "Gogu problem", its joint axes are distributed in space with special geometric conditions, which increases the difficulty of mobility analysis. The study is to calculate the global mobility of the Myard 5R linkage using the mobility methodology. Firstly, the mobility methodology based on screw theory is briefly introduced. Secondly, some homogeneous transforms are performed accnrding to the D-H parameters and the invarianee of the linkage plane symmetry is revealed, which provides an idea to judge a plane-symmetric loop. The special geometric features of the axes distribution are discussed as well. Finally, the global mobility of the more paradoxical mechanisms.     

平面对称光学系统的像差(I-像差理论的扩展)

扩展平面对称光栅系统的像差理论,使之适用于光线斜入射下平面对称折射光学系统的像差计算。结果使反射、衍射、折射光学系统的像差系数用同一组公式表达;应用基于费马原理的光线追迹解析法可以验证结果表达式的正确性。阐述了如何应用我们的波像差系数,导出轴对称对称光学系统的赛德尔初级像差。另外,文章还研究了当主光线位置改变所产生的像差修正。     

On completing the determination of existence criteria for overconstrained 4-bars with helical joints

Many workers have been responsible for the isolation of individual overconstrained 4-bar linkage solutions. Such loops are also included as special cases in the classes of solutions found systematically by a very small number of researchers. A completely general analysis was only recently undertaken. The present paper confirms or corrects and consolidates prior work, generalising where necessary, and completes the analysis of 4-bar spatial chains, with the exception of two linkages which have had to be separately investigated. The results of this analysis, previously unpublished, are tabulated at the end of the paper.     

Synthesis of adjustable planar 4-bar mechanisms

The ability of planar 4-bar mechanism, to generate various kinds of motion, can be greatly enhanced if it is made adjustable. With a simple adjustment of the position of the driven crank fixed pivot(s), a variety of outputs can be obtained with the same set of hardware.

This paper outlines synthesis techniques for 4-bar linkages, having adjustable driven crank pivots, for different motion generation problems. For a 4-bar mechanism, no more than five design positions can be specified. All the possible maximal motion specifications for the two “phases”, consisting of different combination of the five positions, are enumerated. This leads to four classes of motion generation problems. Synthesis procedure for each class is presented. An example of the P₁-P₂-P₃:P₁-P₄-P₅ case is solved. The method of solution is analytical in nature, and, therefore well suited for use on a digital computer.     

On 5-revolute linkages with parallel adjacent joint axes

Although by no means straightforward, the analysis of 4-bar linkages is relatively fertile, because of the symmetries and other special properties bestowed upon the loops by virtue of the even numbers of links. Consequently, mobile chains with 5 members appear somewhat sparsely in the literature. Some systematic and intuitive progress has been made, but much remains unknown. In this paper, we explore a previously untried field of significance to a complete determination of 5-bar linkages. We find that there can be no general 5-R solution with parallel adjacent joint axes, but we are enabled to extend previous work on 5-R loops. Opportunity is also taken to present for the first time a comprehensive listing of known 6-R linkages.     

面对称Bricard-like机构的设计与研究

由于空间单环机构巧妙的几何约束,Bennett机构、Bricard机构等被陆续提出并被广泛研究。将多个反四边形机构通过转动副回环连接,可以构造一类新型空间机构,该类机构具有类似空间单环机构的运动特点。提出了一种类似面对称Bricard机构的面对称Bricard-like机构。该Bricard-like机构由两个相同的反四边形单元和一个反平行四边形单元构成。根据反四边形单元的运动特点,将Bricard-like机构简化为变杆长的面对称Bricard机构。而后通过分析其等价6R机构的D-H参数及闭环方程,得到了该机构的自由度以及运动轨迹。此外,根据运动轨迹,分析了该机构的运动特性,揭示了该机构能够实现内翻运动和外翻运动,进而实现无限翻转运动。并讨论了该机构的无限翻转的可行性条件,给出了构造无限翻转机构的约束条件。最后通过制作样机模型,验证了构造方法的可行性和理论分析的正确性。     

影响双曲柄铰接五连杆机构连杆曲线的因素

介绍了铰接五连杆机构的连杆曲线的求解方法，分析了影响铰接五连杆机构连杆曲线的因素，绘出了几种特殊的铰接五连杆机构的连杆曲线，并简要介绍了铰接五连杆机构的应用前景。     

立式双螺杆制冷压缩机性能分析

研究了立式螺杆制冷压缩机的结构特点.并对立式螺杆制冷压缩机与卧式螺杆制冷压缩机进行了分析比较:立式螺杆压缩机的轴向力比卧式压缩机的轴向力减少57%;立式螺杆压缩机的容积效率要比卧式压缩机的容积效率高5%;由于油分的特殊环形设计,所以立式压缩机的油分效果要比卧式压缩机的油分效果好;而立式压缩机占地面积为卧式压缩机的1/3.     

多直线导向机构的综合方法

本文利用类四杆五杆机构连杆曲线的变化规律，建立了多直线导向机构综合的作图逼近法和近似解析法，讨论了类四杆五杆多直线导向机构直线段参数的确定方法。     

五杆双输入机构的输出特性图谱及输出特性分析

利用ＦＦＴ对常用的典型五杆双自由度机构，在其输入均为匀速转动的条件下，建立了其输出特性－输出函数和连杆上轨迹的特征参数图谱，并对其输出特性与五杆机构的尺度、输入角速度、输入转角的初始值之间的关系进行了分析，得到一些规律性的结论，有助于利用五杆机构的输出特性图谱进行五杆机构的尺度综合，并为多杆机构的特性研究提供了帮助．     

Shaking force balancing of planar linkages with force transmission irregularities using balancing idler loopsVollständiger trägheitskraftausgleich von ebenen koppelgetrieben mit ungleichmässiger kraftübertragung durch schleifen

The article first shows 4-bar, 6-bar and 8-bar planar mechanisms with force transmission irregularities in which an unbalanceable shaking force is generated by a link or by a group of links that have connections to the fixed link through pairs permitting linear freedoms only. Complete shaking force balancing of such mechanisms with force transmission irregularities using the method of linearly independent mass vectors and the concept of balancing idler loops in presented. Design equations for the complete shaking force balancing of some 4-bar, 6-bar and 8-bar mechanisms with force transmission irregularities are given. A numerical example is included.     

Design of geared 5-bar mechanisms for unlimited crank rotations and optimum transmission

This investigation is concerned with the determination of the rotatability of the geared cranks and the optimization of transmission characteristics of geared 5-bar linkages. Algebraic solutions are shown to be feasible only in a few, special cases. An efficient computer-aided procedure, however, can be used for the general case and for the development of design charts. These charts, which are given for the mechanisms with gear ratio minus one, can be used to determine whether a mechanism of given proportions possesses unlimited crank rotations and to select the floating-link dimensions yielding optimum transmission.     

A note on symmetrical self-oscilating coupler curvesBemerkungen über symmetrische selbstoskulierende koppelkurven

Some special symmetrical coupler curves, from hinged planar 4-bar linkages, are presented which not only touch themselves but which osculate with themselves where three double points coalesce. Possible applications in point-guidance are touched on.     

The E---H---H---H-linkage

Most single-loop 4-bar overconstrained lower-paired linkages with mobility one have now been isolated. The solutions of all but three appear in publications and/or dissertations. Of the three, the H---H---C---C-loop has recently been fully analysed and will be published separately. The subject of the present paper is the solution of the E---H---H---H-chain. This and the S---H---H---H-loop are especially difficult to treat because of the number of screw joints present. By means of a theorem published earlier, however, the E---H---H---H-linkage is made amenable to analysis, using closure equation algebra and the spherical indicatrix.     

Overconstrained 5-bars with parallel adjacent joint axes—II The linkages

In this Part of the paper, we apply the technique outlined in Part I to examine all 5-bar loops containing lower pairs, for all combinations of parallel adjacent joint axes, with a view to isolating the linkages which have mobility one, but are free from part-chain mobility. We achieve total success in all categories but one. In the process, we discover a new linkage. Finally, we indicate what needs to be done to complete the solution of the 5-bar existence problem.     

受控机构实现轨迹的运动误差研究

刚性受控五杆机构实现给定轨迹因结构参数误差引起的运动误差，以受控原动件运动误差最小为目标，采用最小范数法确定刚性受控五杆机构各杆结构参数误差；在此基础上，进一步分析受控原动件运动误差变动与实现给定轨迹误差间的关系，为受控原动件的选择提供重要的依据。     

消除异形螺纹形状误差问题的探讨和研究

本文通过对异形螺纹中的波形螺纹形状和加工工艺进行分析,利用宏程序编制出合理的加工程序,有效解决了异形螺纹的形状误差问题.     

Special configurations of spatial mechanisms and robot armsSpezielle konfiguration räumlicher mechanismen und roboterarme

A novel general method is developed for determining special configurations of all single-loop mechanisms. The results are illustrated by means of numerical examples. In addition special configurations of robot arms are investigated, and a simple result which has important practical application is deduced; “when all the screws representing the instantaneous motion of the joints of a robot arm are reciprocal to a common screw or screw then the end effector cannot have free instantaneous movement parallel to the axis or axes of the reciprocal screws”.