变桨四旋翼倒飞的建模与控制
Modeling and Control of Inverted Flight of a Variable-Pitch Quadrotor
AI总结：
本文针对变桨四旋翼的倒飞问题，提出基于动态反演的非线性控制设计，通过三重闭环结构解决旋翼扭矩非线性问题，实现姿态稳定与轨迹跟踪，并通过翻转 maneuver 验证了反推力能力。
摘要：
本文对具有变桨推进器的四旋翼进行了数学建模、仿真和控制律设计。利用变桨推进器实现负推力生成，提升机动性能。结合翼剖面理论和动量理论估算推进器推力与扭矩，用于建立运动方程。所提飞行动力学模型用于非线性控制设计，用于稳定、跟踪参考轨迹和模拟翻转 maneuver。旋翼扭矩是控制输入的无理函数，使控制设计具有挑战性。为此，控制设计采用三重闭环结构：外环解决平动动力学以生成推力、俯仰角和滚角指令；内环简化旋转动力学以提供所需角速度率；控制分配环通过引入推力系数导数作为虚拟控制输入，确定推力和身体力矩的导数，从而生成所需推力和身体力矩。通过实飞验证姿态稳定性和仿真结果展示性能，通过翻转 maneuver 验证了变桨四旋翼的反推力能力。
英文摘要：
This paper carries out the mathematical modeling, simulation, and control law design for a quadrotor with variable-pitch propellers. The use of variable-pitch propeller for thrust variation instead of RPM regulation facilitates generation of negative thrust, thereby augmenting the rate of change of thrust generation amenable for aggressive maneuvering. Blade element theory along with momentum theory is used to estimate propeller thrust and torque essential for formulating equation of motion of the vehicle. The proposed flight dynamics model is used for non-linear control design using dynamic inversion technique, which is then used to stabilize, track reference trajectory, and simulate flip maneuver. The rotor torque is an irrational function of the control input which makes the control design challenging. To address this problem, the control design employs three loops. The outer loop solves the translational dynamics to generate the thrust, pitch angle, and roll angle commands required to track the prescribed trajectory. Using the command generated in the outer loop, the inner loop simplifies the rotational dynamics to provide the desired rate of angular velocities. A control allocation loop is added to address the problem of nonlinearity associated with rotor torque. This is done by introducing the derivative of thrust coefficient as a virtual control input. These virtual inputs determine the derivatives of thrust and body moments, which in turn is used to generate the required thrust and body moments. The concept is validated by showing attitude stabilization in real flight for a variable pitch quadrotor. The performance of the proposed design is shown through simulated results for attitude stabilization and trajectory following. Reverse thrust capability of variable-pitch quadrotor is also shown by performing flip maneuver in which quadrotor roll angle changes from 0 to 180 degrees.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
