METHOD USED IN SINGULARITY RESEARCH BASED ON KINEMATICS AND ITS EXAMPLE IN APPLICATION

First the kinematic principle of singularity is proved, that is the intersecting point of three normal planes of three velocities at three non-collinear points in a rigid body lying in the plane determined by the three corresponding points. It is a sufficient and necessary condition that the velocities of three non-collinear points in a rigid body can determine a screw motion of the body. Based on this principle, a simple and direct new method to distinguish the singularity of the parallel manipulator is derived. With this new kinematic method, the 3-RPS parallel manipulator is studied. Its singularity loci are obtained for some orientations for the fast time and verified with Grassmann line geometary and screw theory and the force Jacobian matrix.     

粘滞阻尼器粘弹性效应分析与研究

粘滞阻尼器因其具有的优良性能,在实际工程中得到了广泛的应用.随着对粘滞阻尼器研究的深入,发现其具有一定的刚度.本文通过研究认为,粘滞阻尼器产生刚度的根本原因是阻尼介质具有一定的粘弹性效应,在对此分析的基础上,建立了粘滞阻尼器考虑粘弹性效应影响的力学模型,并对其进行了试验与仿真分析,结果表明该阻尼器模型能够较好地反映其实际力学性能,可为粘滞阻尼器的设计与应用提供有益的借鉴.     

STUDY OF REGULARITY OF GENERAL-LINEAR-COMPLEX SINGULARITY OF 3／6-STEWART MECHANISM

The general-linear-complex singularity of Stewart mechanism is a very important problem in the parallel manipulator. Its general regularity is not found yet during the past two decades. StOnge and Gosselin pointed out that the singularity locus of the Stewart mechanism at some given orienb-tions of the moving platform should be polynomial expressions with varied degrees in 2000, but they didn't formulate the expression. Based on the kinematics singularity principle and the geometry cond-tion proposed by Huang Zhen in 1999, firstly the singularity equation in degree two is derived. It is a hyperbola when the orientation of the moving platform is given. This result is also proved using screw theory. Then some singularity surfaces are gotten in three-dimensional space. This result is of impcr-tant significance.