The results are believed the first attempt that resolves the circuit identification problem of the spatial linkages with four closures . the theory of type transformation of planar linkages has been extended to the kinamatic analysis of spatial linkages . the structural decomposing criterion and its automatic generation algorithm for multi - loop spatial linkages are discussed 将平面连杆机构运动分析的型转化和广义型转化理论拓展到空间连杆机构的运动分析，得出了型转化法全间连杆机构的结构分解准则及其自动生成算法:给出了以型转化单元为结构单元的空间机构单元划分方法。
In the paper , based on the method of low pair replacing with high pair , the problem of cam design was transferred to that of linkage design . by means of rotary unit vectors , the equations of displacement , velocity and acceleration of the replacement mechanisms were developed . and then , the virtual linkage ' s length and direction were deduced 论文基于高副低代原理，将平面凸轮机构设计与再现函数的平面连杆机构设计统一为同一种方法，运用圆向量函数建立代换机构的位移、速度、加速度矢量方程式，求取虚拟连杆杆长和方向，由此展开凸轮理论廓线、实际廓线、曲率半径和压力角的求解，并得出用圆形刀具加工凸轮时刀具中心的轨迹方程。
Nevertheless , the widely existed overconstraints in the mechanisms will make the quality of the mechanisms very sensitive to the inevitable manufacturing , assembly errors ( especially , the errors resulted from the shape and position between kinematic pair elements and their axes ) . at the same time , because the internal and external uncertain factors such as non - plane characteristic of dynamic parameters of links ( such as mass distribution , inertia forces , etc . ) , bending and twist of links , and the changes of environment and operating condition are inevitable , they will form the disturbance to planar constraints and make them possess the characteristic of " uncertain " 但是，平面连杆机构中广泛存在的过约束，造成机构对制造、安装误差特别是运动副元素的形位误差十分敏感；同时，由于不可避免的内部和外部不确定因素的影响，常常会造成机构运动的“障碍”及系统中某些构件的变形和运动副中的附加动载荷，引起机械的振动、冲击、噪声等而导致机械的效率和工作性能的降低。
The uncertainty of planar constraints causes overconstraints , which have no influences in the ory on smooth work of a machine with planar linkages , to form obstruction in fact and bring about a series of pernicious influences on the performance of the machines , especially on their dynamic behavior and the quality 因此，本文以平面连杆机构为研究对象，以高效、高稳定性及低成本为主要目标，对机械中的约束与过约束、自调机理与自调结构、运动副误差对平面连杆机构约束不确定性的影响程度以及无过约束机构的设计理论与方法进行了深入、系统的研究。
