三轴承推力矢量喷管运动学建模及试验

三轴承推力矢量（3BSD）喷管是实现大角度偏转的推力矢量主要形式，主要应用于垂直/短距起降（V/STOL）飞机。喷管由3段组成，相邻两段通过轴承连接，喷管与发动机出口也通过轴承连接，因此形成了3对转动副，通过3对转动副的转动喷管可以实现偏转到特定的角度及方向。三轴承推力矢量喷管运动学模型是其控制器设计及应用的前提，通过喷管固联坐标系逐级坐标转换的方法得到喷管运动学模型。通过几何关系分析说明了三轴承推力矢量喷管的基本原理，对推力矢量偏转大小/方向与三级喷管转角之间的非线性关系进行了分析，在3条基本假设的基础上提出了喷管逆运动学控制规律，并利用一个缩比喷管进行了试验验证。试验结果表明，所建立模型可以反映喷管运动学特性，逆运动学控制规律可应用于喷管开环控制。

Kinematic Modeling and Testing of 3-Bearing Swivel Duct Nozzle

The 3-bearing swivel duct (3BSD) nozzle is the main form of large angle deflection. It is chiefly used on vertical and/or short take-off and landing (V/STOL) aircrafts. A 3-bearing swivel duct nozzle contains three ducts. The three ducts and the engine outlet are connected by three bearings thus forming three revolute pairs. The nozzles deflect to a desired angle and direction through the rotation of the revolute pairs. Kinematic modeling is the prerequisite of the design and application of a 3-bearing swivel duct nozzle. A kinematic model is built in this paper using coordinates transformation. Principles of the nozzle are presented through geometric analysis. The nonlinear relationship of the nozzle deflection angle/direction and rotation angles of the three revolute pairs is discussed. The inverse kinematic control law is given, based on three proposed assumptions, and tested on a scaled 3-bearing swivel duct nozzle. The experiment results show that the kinematics model reflects the kinematic behavior of the 3-bearing swivel duct nozzle precisely, and the inverse kinematic control law can be used for its open loop control.