提出一种新型共轴式少自由度混联机构，可以模拟三桨叶共轴式直升机操纵机构的运动，由下操纵3-SPS+PS+RRS并联机构和上操纵混联机构串联而成，整体机构结构简单紧凑，所以可应用于三桨叶共轴式无人机。机构对旋转盘的约束等效为一个PS约束支链，上操纵混联机构等效为几个并联机构后，运用螺旋理论分析上操纵机构的自由度，证明上下倾斜盘运动姿态一致，结合下操纵机构得出整个机构满足三桨叶共轴直升机操纵机构所需的自由度。对上操纵机构中的倾斜盘的姿态角和运动支链的位置进行分析，并得出了在下操纵机构一定倾斜姿态下变距转动角的变化规律。通过PRO/E仿真查看整体机构的运行情况。
A new coaxial reduced degree of freedom (DOF) hybrid mechanism is put forward. The mechanism is a series formed coaxial hybrid mechanism which is composed of a 3-SPS+PS+RRS parallel mechanism and a hybrid mechanism. The overall mechanism has simple and compact structure, so it can be applied in the three blade coaxial unmanned helicopter. The restrain of 3-SPS+PS+RRS parallel mechanism is eauivalent restrain of PS subchain. The hybrid mechanism is decomposed into several equivalent parallel mechanisms. The degree of freedom of swashplate mechanism is analyzed by screw theory and the upper swashplate and lower swashplate are proved to keep the same posture. A conclusion is reached that the whole coaxial hybrid mechanism satisfying degrees of freedom of the operating mechanism of three blade coaxial helicopter under the consideration of the lower parallel mechanism. The position of upper operating mechanism is analyzed and the variation of the rotation angle of three pitchs is studied when the swashplate keep the inclined posture. The whole operation mechanism is simulated through PRO/E.
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