ass日本风韵熟妇pics男人扒开女人屁屁桶到爽|扒开胸露出奶头亲吻视频|邻居少妇的诱惑|人人妻在线播放|日日摸夜夜摸狠狠摸婷婷|制服 丝袜 人妻|激情熟妇中文字幕|看黄色欧美特一级|日本av人妻系列|高潮对白av,丰满岳妇乱熟妇之荡,日本丰满熟妇乱又伦,日韩欧美一区二区三区在线

A new non-overstrained four-DOF parallel kinematic mechanism (PKM) for realizing three-dimensional translations and rotation is presented, which is composed only with revolute joints. The topological structure characteristics, such as the POC set of moving platform, mobility and the mechanism coupling degree, are first obtained based on the design theory of position and orientation characteristic (POC) set. By means of the D—H matrix, the kinematic inverse equations of the PKM are established and Jacobian matrix, singularity are subsequently derived and analyzed. The virtual mechanism is modeled and the kinematics is simulated by using Pro/E software. By comparing the theoretical calculation analysis of examples with the results derived from simulation, the inverse positional solutions are proved to be correct. Based on the kinematic inverse equations, the 3D boundary search method is used to describe the geometrical feature and cross section of constant orientation workspace. Furthermore, the distribution of singularity position is presented and the rotational capacity among the workspace is evaluated. The results show that the workspace has regular geometrical shape and the rotational capacity is satisfactory, but the singular may appear in the workspace. Hence, it is necessary to obtain the singularity-free workspace of the PKM, which can guarantee the mechanism to avoid singularities. The study has guiding significance and reference value to the design and control of this kind of PKM.