Position information, produced by the image recognition, is
subjected to delays and signal outages before it reaches the control
input of the quadrocopter. One major drawback of direct visual
servoing is the need for the target to stay inside the field of
view of the camera. In the case of the quadrocopter under direct
visual servo control, one must be aware of the unstable nature
of this aircraft. This nature requires a functioning visual servoing
loop, which is directly dependent on the visibility of the target
by the camera. Therefore, an indirect visual servo-control was
developed that uses a combination of local position tracking with
an integrated IMU unit and an image-based position estimation
and filtering with a Kalman filter. The additional dynamic delay
estimation and compensation system was included in the position
filtering process.