UAV's Precise Trajectory Tracking Control Based on Nonlinear Dynamic Inverse and Quaternions

基于四元数和动态逆的无人机精确航迹控制

¹ School of Aeronautics, Northwestern Polytechnial University Xi'an, 710072, China
² Skyline Technologies, Xi'an, 710072, China

Received: 8 2019

Abstract

The precise tracking 3D trajectory that changes dramatically within the boundary of flight performance is the essential capability of the UAV applied to air combat, which requires that flight control law design be adapted to nonlinear characteristics of flight dynamics and solve the singularities problem during the flight. Continuous trajectory control on the basis of nonlinear dynamic inversion (NDI) is studied. The singularities problem is caused by continuous trajectory expressed by flight velocity and flight-path angles. A sudden change of flight-path axis system happens when aircraft flies along a continuous trajectory which results in singularities. A method for amending flight-path axis system is presented to solve the sudden change problem of flight-path axis system. Finally, the combination of the maneuver generator based on quaternions and amending flight-path axis system realize the precise trajectory tracking control without singularities and obtain excellent tracking characteristics.

摘要

精确跟踪飞机飞行性能边界内剧烈变化的三维航迹是无人机应用于空战的关键问题，这要求飞机的飞行控制律设计不仅要适应动力学的非线性特性还要解决飞行过程中的奇异性问题。在非线性动态逆（NDI）理论的基础上探讨了连续航迹的控制问题，聚焦于飞机飞行速度和航迹角描述航迹产生的奇异性（也称万向节死锁），针对当飞机在沿引发奇异性的连续航迹飞行时，航迹坐标轴系会出现突变的现象，提出了一种修正航迹轴系的方法来解决航迹坐标轴系经过奇异点突变的问题。最终，设计了基于四元数的机动产生器，结合提出的修正航迹轴系方法，实现了不会产生奇异性问题的精确航迹控制，并且取得了良好的跟踪效果。