A robust attitude quadrotor control based on a novel fractional order PI nonlinear structure is proposed and experimentally validated. The proportional action depends on a nonlinear transformation of the sliding variable, while the integral action of fractional order rejects nondifferentiable disturbances, such as turbulent effects and gust winds, enforcing a sliding motion in finite time. The exponential convergence of a quaternion-based error is guaranteed for well-posed attitude tracking, and the regularity of the control signal can be adjusted with respect to the fractional order. Notably, the proposal includes, as particular cases, first-order and second-order sliding mode control schemes. Experiments illustrate the viability of the proposal, and a comparative study versus PD, PI-like, first-order sliding mode and second-order sliding mode supertwisting controllers is presented and discussed.

中文翻译：

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用于四旋翼飞机姿态跟踪的分数阶非线性 PI 结构控制

提出并通过实验验证了一种基于新型分数阶 PI 非线性结构的鲁棒姿态四旋翼控制。比例作用取决于滑动变量的非线性变换，而分数阶积分作用拒绝不可微扰，如湍流效应和阵风，在有限时间内强制滑动。适定姿态跟踪保证了基于四元数的误差的指数收敛，并且可以相对于分数阶来调整控制信号的规律性。值得注意的是，作为特殊情况，该提议包括一阶和二阶滑模控制方案。实验说明了该提案的可行性，以及与 PD、PI 类似的比较研究，