中文摘要：

根据放大尺原理构建具有大缩放比的六自由度菱形运动支链和四自由度菱形运动支链，将其作为并联机构组成支链，提出一种具有结构紧凑、工作空间大的新型四自由度并联机器人机构．依据等效替换原理，将菱形机构虚拟轴用传统串联运动支链的实轴替代，得到新型四自由度并联机构的等效模型．利用螺旋理论分析了新型并联机构等效模型各支链的运动螺旋系和约束反螺旋系，确定并联机构动平台具有两个移动自由度和两个转动自由度．

英文摘要：

AceoMing to the principle of scaling ruler, 6-DOF （degree of freedom） and 4-DOF rhombus kinematic chains with a large pantograph ratio have been constructed to form the parallel manipulator, and based on this, a novel 4-DoF parallel manipulator with a compact structure and a large workspace is proposed. Based on the equivalent substitution principle, an equivalent model of 4-I）oF parallel ma- nipulator can be designed by the way of replacing virtual axis of rhombus mechanism with the real axis of serial kinematic chains. In addition, screw theory was used to analyze the DOF. In the analysis of the kinematic screw system and reciprocal screw system of constraints in the equivalent model of paral- lel manipulator, two translational DOF and two rotational DOF can be confirmed in the parallel moving platform.