Nonlinear control of unmanned aerial vehicles with, cable suspended payloads

This paper fOcuses on the mathematical modeling and control of an unmanned aerial system (UAS) with a payload suspended using a cable. The motion of the payload induces disturbances on the aerial platform and needs to be mitigated for stable operation. The solution to this control problem is presented through the implementation of a passivity based controller, and an extended state observer based active disturbance rejection controller. The implementation of the passivity based controller requires the knowledge of higher time derivatives of the payload oscillations. Assuming only the swing angles of the payload with respect to a UAS are measured, these states (primirily the angular velocity) are estimated using a continuous-discrete Kalman Filter. Alternately since, the payload cable swing angle is difficult to measure, an active disturbance rejection controller is designed and implemented wherein the disturbance induced in the system due to the motion of 'the payload is estimated using the extended state observer. A comparison between ,the passivity based controller and the extended state observer based active disturbance rejection controller is performed using a high fidelity numerical simulation. (C) 2019 Elsevier Masson SAS. All rights reserved.