This paper presents a method to recover quadrotor UAV from a throw, when no control parameters are known before the throw. We leverage the availability of high-frequency rotor speed feedback available in racing drone hardware and software to find control effectiveness values and fit a motor model using recursive least squares (RLS) estimation. Furthermore, we propose an excitation sequence that provides large actuation commands while guaranteeing to stay within gyroscope sensing limits. After 450ms of excitation, an INDI attitude controller uses the 52 fitted parameters to arrest rotational motion and recover an upright attitude. Finally, a NDI position controller drives the craft to a position setpoint. The proposed algorithm runs efficiently on microcontrollers found in common UAV flight controllers, and was shown to recover an agile quadrotor every time in 57 live experiments with as low as 3.5m throw height, demonstrating robustness against initial rotations and noise. We also demonstrate control of randomized quadrotors in simulated throws, where the parameter fitting RMS error is typically within 10% of the true value.

翻译：本文提出了一种在抛掷前未知任何控制参数的情况下，恢复四旋翼无人机（UAV）飞行状态的方法。我们利用竞速无人机硬件和软件中可用的高频转子转速反馈，通过递归最小二乘（RLS）估计来获取控制效能值并拟合电机模型。此外，我们提出了一种激励序列，该序列在保证不超出陀螺仪传感极限的前提下提供大幅度的驱动指令。经过450毫秒的激励后，增量非线性动态逆（INDI）姿态控制器利用拟合出的52个参数来抑制旋转运动并恢复直立姿态。最后，非线性动态逆（NDI）位置控制器将飞行器驱动至目标位置。所提算法能在常见无人机飞控的微控制器上高效运行，并在57次实机实验中，以低至3.5米的抛掷高度，每次都成功恢复了敏捷四旋翼飞行器，证明了其对初始旋转和噪声的鲁棒性。我们还在模拟抛掷实验中展示了对随机参数四旋翼飞行器的控制能力，其中参数拟合的均方根误差通常在其真值的10%以内。