基于平面约束不确定性的自调性机构设计

普遍使用的平面闭链机构是在理想平面约束条件下，作者选择曲柄摇块机构为例，分析了制造误差等不确定性因素对理想平面约束的影响，结果表明它属于静不定机构。通过过约束理论分析，消除机构中的过约束，使其成为静定机构，能够实现无障碍装配。然而，在实际运行过程中，机构可能新生运动约束，又出现过约束，它能否避免自锁现象，自动调整位置和姿态，时时处于静定状态，还要进行自调性分析。研究表明，自调性机构设计一般要先消除几何过约束，再分析运动过程中的各种外部约束能否形成新的过约束。

Adjustive Mechanism Design Based on Planar Constraint Uncertainty

For normal planar closed chain mechanism, it is based on ideal planar constraint condition. The authors took crank leader mechanism as an example, and analyzed influences resulted from uncertain factors, such as manufacturing error. The result shows it belongs to statically indetermination mechanism. After analyzing its over-constraint and eliminating it, in this way, it become statically determination mechanism and can be assembled without obstacle. However, in the process of practical running, the mechanism can give birth to new kinematic constraint, frictional constraint and dynamic constraint etc., so over constraint emerges again. Therefore, it is necessary to analyse its adaptability in total running process. The conclusion shows that design of adaptability mechanism normally eliminate geometry over constraint at first, then it is analyzed that whether there is new over constraints from all kind of external constraints in the process of running.