Model identification and data fusion for the purpose of the altitude control of the VTOL aerial robot

In this paper we focus on the problem of the altitude control for an unmanned aerial vehicle known as quadrotor. One of the requirements for the proper operation of altitude control system, are reliable estimates of the UAV altitude and vertical velocity. In this paper altitude and vertical speed estimation algorithm in a form of the Kalman filter is presented which makes use of the ultrasonic range finder and accelerometer. On the basis of the estimates, the nonlinear Hammerstein-Wiener model of the velocity and parametric model of altitude are constructed. Next, the model of the quadrotor vertical movement is used in a process of cascade control system design. Finally, the verification of the controllers has been performed on the hardware platform, and the performance of the altitude controller has been examined.