为了研制面向精密工程的微动角位移机构,采用旋量代数分析了3-HSE和3-HSVR三螺旋角位移机构的自由度和约束模式.分析表明,基于“不共线三点确定一个平面”设计的角位移机构存在欠约束和欠确定运动问题,由此导致机构的位姿和运动具有不确定性.因此,提出了双螺旋式精确约束二自由度角位移机构.这种机构在自然状态下采用六点约束,具有确定位姿;在输入状态下自由度数等于输入数,具有确定运动.采用矢量运动变换方法证明了机构在不同输入模式下的姿态调整原理并利用机构运动几何关系分析了机构灵敏度,结果表明,该角位移机构灵敏度优于0.83μrad.这种角位移机构仅采用两个螺旋支链,结构简单、位姿和运动确定、稳定性高,可用于两个自由度的姿态调整.%In order to design a micro-motion angle displacement mechanism for precision engineering, the degrees of freedom and constraint patterns of 3HSE and 3HSVR angle displacement mechanisms with three screws were analyzed, and it shows that the common angle displacement mechanisms designed via three point supports have the uncertainties of the orientation and motion. Therefore, an exact constraint angle displacement mechanism with double screws was presented. The mechanism is exactly constrained by six point constraints, so that the position and orientation are deterministic at the natural state. Moreover, the number of degrees of freedom of the mechanism are equal to the number of the inputs and its motion is also deterministic at the input state. Furthermore,the adjusting orientation principles under different inputs were proved and the sensitivity was analyzed via the relationship of kinematic geometry. The result indicates that the sensitivity of the mechanism is superior to 0. 83 μrad. The analysis shows that the proposed angle displacement mechanism has good stability and is suitable for the angle adjustment involving two degrees of freedom in precision engineering.
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