中文摘要：

用传统方法对并联机构或复杂机构进行受力分析是十分不方便的,尤其是要计算所有运动副的约束反力时,常常需要联立大量的方程才能得到最终结果。基于螺旋理论对这类机构进行受力分析会使这个问题简化。运用此方法可以方便地求出在外力作用下机构的主动力和所有运动副的约束反力,并且对于主动力和各运动副的约束反力是以单独构件逐个求解为特点的,可以确保分析每个杆件联立求解的方程数目不多于6个。为详细说明基于螺旋理论对这类机构进行受力分析的方法的优点,以由两个转动副、一个球副和一个万向铰组成的一个单环空间机构为例运用此方法求解其主动力和所有运动副的约束反力,通过求解就可以看出运用此方法可以使机构的受力分析过程大大简化,并且思路清晰容易理解。

英文摘要：

The force analysis of parallel mechanism or complex mechanism by using the traditional method,especially,when it needs to calculate constraint reactions of all kinematic pairs,is quite inconvenient because a large number of simultaneous equations need to be solved.Using screw theory to analyze such mechanisms will simplify the problem.With this method,it can develop the force analysis of the mechanism including active forces under external force and constraint reactions of all kinematic pairs,and it can deal with the active forces and constraint reaction forces of every kinematic pair respectively.The advantage is that the method can ensure the number of equilibrium equations being no more than six each time.For understanding the characteristics of this force analysis method based on screw theory,a single-loop spatial mechanism is taken as an example,which consists of two revolute pairs（R）,a spherical pair（S） and a universal pair（U）,i.e.RSUR mechanism.It needs to solve its active forces and constraint reactions of all kinematics pairs with this method.Through the solution it can be seen that the method greatly simplifies the process of calculating the force analysis and the solution process is clear and easy to understand.