目的 研究Delta并联机构分支数目和驱动副分布对机构运动约束的影响。方法 使用Study参数表示刚体的位移、姿态变换矩阵，根据运动链D-H参数，建立运动链约束方程，再进行坐标变换得到分支约束方程，分析驱动副分布对Delta类并联机构运动约束的影响。结果 分支数目为3和4时，驱动副无论如何分布，delta并联机构只具有移动的运动特征。结论 用统一的表达式来表示Delta并联机构的约束情况更为直观，也为Delta并联机构设计优化提供了新的思路。

The work aims to study the number of branches of Delta parallel mechanism and the influence of driven joint distribution on the kinematic constraints of mechanism. Study parameters were used to represent the displacement and attitude transformation matrix of a rigid body. According to the D-H parameters of kinematic chain, constraint equations of kinematic chain were established, and then the branch constraint equations through coordinate transformation were obtained. The effect of driven joint distribution on the kinematic constraints of Delta parallel mechanism was analyzed. When the branch number was 3 and 4, no matter how the driven joint was distributed, the delta parallel mechanism was only characterized by movement. The unified expression used to indicate the constraining conditions of Delta parallel mechanism is more intuitive, and provides a new idea for its optimized design.