Cascaded Incremental Nonlinear Dynamic Inversion Control for MAV Disturbance Rejection
This addresses the issue of MAV stability under severe wind disturbances for outdoor operations, representing an incremental advancement in control methods.
The paper tackles the problem of Micro Aerial Vehicles (MAVs) struggling with wind gusts outdoors by generalizing Incremental Nonlinear Dynamic Inversion (INDI) control to outer loop control, demonstrating significant improvements over PID controllers in experiments with 10 m/s wind gusts and showing it works with standard GPS.
Micro Aerial Vehicles (MAVs) are limited in their operation outdoors near obstacles by their ability to withstand wind gusts. Currently widespread position control methods such as Proportional Integral Derivative control do not perform well under the influence of gusts. Incremental Nonlinear Dynamic Inversion (INDI) is a sensor-based control technique that can control nonlinear systems subject to disturbances. It was developed for the attitude control of manned aircraft or MAVs. In this paper we generalize this method to the outer loop control of MAVs under severe gust loads. Significant improvements over a traditional Proportional Integral Derivative (PID) controller are demonstrated in an experiment where the quadrotor flies in and out of a windtunnel exhaust at 10 m/s. The control method does not rely on frequent position updates, as is demonstrated in an outside experiment using a standard GPS module. Finally, we investigate the effect of using a linearization to calculate thrust vector increments, compared to a nonlinear calculation. The method requires little modeling and is computationally efficient.