Inversion based direct position control and trajectory following for micro aerial vehicles

In this work, we present a powerful, albeit simple position control approach for Micro Aerial Vehicles (MAVs) targeting specifically multicopter systems. Exploiting the differential flatness of four of the six outputs of multicopters, namely position and yaw, we show that the remaining outputs of pitch and roll need not be controlled states, but rather just need to be known. Instead of the common approach of having multiple cascaded control loops (position - velocity - acceleration/attitude - angular rates), the proposed method employs an outer control loop based on dynamic inversion, which directly commands angular rates and thrust. The inner control loop then reduces to a simple proportional controller on the angular rates. As a result, not only does this combination allow for higher bandwidth compared to common control approaches, but also eliminates many mathematical operations (only one trigonometric function is called), speeding up the necessary processing especially on embedded systems. This approach assumes a reliable state estimation framework, which we are able to provide with through previous work. As a result, with this work, we provide the missing elements necessary for a complete approach on autonomous navigation of MAVs.