## 3 Experimental Results
The UAV does not try to follow a continuous trajectory, though it tries to reach the predefined waypoints. The UAV reaches each waypoint with an error lower than 4 cm (see Figure 15). Figure 10: \(X\)-axis motion during one of the trials. Figure 9: \(Z\)-axis motion during one of the trials. Figure 11: \(Y\)-axis motion during one of the trials. Figure 12: The roll angle of the UAV in clip installation. Figure 13: The pitch angle of the UAV in clip installation. The operation performed during step 4 is illustrated in detail in Figure 16. First, the guide leads the cable inside the clamps (Figure 16a). The insertion operation is triggered when the cable is placed in the middle of the clamps and touching the clip (Figure 16b). The linear actuator stretches out, moving the clamps (Figure 16c) until they are fully closed around the cable (Figure 16d). Then, the actuator continues pushing the bird diverter until the cable is clipped (Figure 16e). Then, the actuator retracts, opening the clamps (Figure 16f); then, the clamp moves back (Figure 16g), and the aerial robot flies up, leaving the bird diverter deployed (Figure 16h). Figure 7:0 Yaw angle of the UAV during one of the trials. Figure 7:1 The 3D trajectory of the autonomous clip installation. The effect of the force exerted during the installation on the hovering condition of the UAV is then analyzed. As can be seen in Figure 9, there is only a minor effect on the \(Z\)-axis error due to the vertical force during the installation, but the horizontal error (Figures 10 and 11) and orientation angles (pitch, roll, and yaw, Figures 12-14) are mainly unaffected. Three consecutive trials have been performed to validate the repeatability and robustness and to obtain some timing data. The following three-time intervals are measured:  
* Descending toward cable: the time it takes to navigate from WP2 to WP4 and until the pilot triggers the installation procedure. This time can vary because the pilot triggers the operation when he/she considers the UAV is stabilized enough in WP4. * Clamping: the time the diverter installation tool takes to insert the bird diverter into the cable. Figure 7:2 A series of images to show the sequence of the process; (**a**) approaching, (**b**) positioning the device, (**c**) pushing down the diverter, (**d**) fixing the diverter, (**e**) clamping, (**f**) opening, (**g**) retreating of the linear actuator, (**h**) fly back to station. * Retreat: the time the linear actuator needs to retreat and open the clamps again, plus the time required to fly back to WP3. This time can also vary because the flyback command is manually triggered by the pilot. The time details of the experiments are summarized in Figure 7:3 The average time of the operation is 32.6 s (excluding the time required for take-off and navigation from WP1 to WP2). Descending onto the cable takes an average time of 9 s due to the constrained vertical speed and smoothness required. The clamping and retreating stages are automatic and take identical time (10 s), but, as explained before, the decision to fly back is made by the pilot, so \"Retreat\" values are different in Figure 7:4 It should be noted that the \"Descending Toward Cable\" phase could take quite a different time in a real operation due to the long flight to cable position. The flight time was estimated and recorded 20 min of autonomy, measured approximately. Accounting less than 2 min for each diverter (30-40 s for installation plus fly back and new diverter uploading), a single battery would install 10 diverters. For real outdoor installation, adding a new device for holding several clips is necessary, which changes the current timing on the indoor tests. The flight to the pylon and back to the station would also be different.