一类轴孔装配混联柔性机构构型综合

Type Synthesis of Hybrid Compliant Mechanisms for Peg-in-Hole Assembly

被动装配是实现轴孔高精度配合的重要方法之一,其基本原理为柔性装配机构针对外界装配力与装配反力做出自适应柔顺变形,补偿由于工业机器人定位误差导致的轴孔中心线位移偏差及倾角偏差.作为被动装配方法的核心使能部件,柔性装配机构的性能直接决定装配成功与否,为此,开展了一类基于五自由度混联柔性机构轴孔装配的方案设计和柔性机构构型综合研究.该机构由分别具有2T1R(T表述移动运动,R为转动运动)和3R自由度运动的柔性并联模块串联组成,并采用片弹簧作为实现柔顺变形的基本柔性单元.在整体方案设计的基础上,以旋量作为数学工具,提出一种并联柔性机构构型综合的一般流程,讨论在片弹簧不同变形情况下的支链组成形式,拟定支链装配条件.结合实际工况,本文优选出3-RFS-3-RFS作为轴孔装配的柔性机构,利用有限元软件对得到的机构进行仿真以验证机构自由度及各向柔度,仿真结果表明该机构具备五自由度且各向柔性差异小于0.05%.搭建了轴孔装配实验台,装配实验结果表明对于直径为20 mm与10 mm的轴孔对,装配成功率分别可达90%与70%.

Passive assembly is an important method in peg-in-hole assembly.The assembly and reaction forces result in adaptive deformation of the compliant mechanism,which depends on the deformation to compensate for the position and angular deviations.As the key point of a passive assembly device,the performance of compliant mechanisms determines whether the assembly is successful or not.Therefore,a kind of hybrid compliant wrist with five degrees of freedom,which is composed of two parallel compliant modules with 2 T1 R(T and R denote translational and rotational motions,respectively)and 3 R mobility,was proposed and designed in this study.First,a novel passive assembly device was proposed.Then,using screw as a mathematical tool,a general process for configuration synthesis of parallel complaint mechanisms is proposed.Available limbs were generated on the basis of the deformation conditions of the plate spring and the assembly principles.Finally,the 3-RFS-3-RFS hybrid compliant mechanism was selected for the peg-in-hole assembly.The finite element simulation showed that the hybrid compliant mechanism can adjust the displacement and angle errors well.Moreover,flexibility in all directions is changeable by no more than 0.05%and with no difference in all angles.A peg-in-hole assembly test bench was built.The assembly test results show that the assembly success rate can reach 90%and 80%for peg and hole pairs with diameters of 20 and 10 mm,respectively.