Novel Haptic Cues for UAV Tele-Operation

Both remote piloted systems for Unmanned Aerial Vehicles and Fly-By-Wire systems for manned aircrafts do not transfer to the pilot important information or cues regarding the state of the aircraft and the loads which are being imposed by the pilot's control actions. These cues have been shown to be highly responsible for pilot situational awareness; this has a negative impact on system performance especially in the presence of remote and unforeseen environmental constraints and disturbances.

Extending the visual feedback with force feedback is able to complement the visual information (when missing or limited). An artificially recreated sense of touch (haptics) may allow the operator to better perceive information from the remote aircraft state, the environment and its constraints, hopefully preventing dangerous situations. The dissertation introduces first of all a novel classification for haptic aid systems in two large classes: Direct Haptic Aid (DHA) and Indirect Haptic Aid (IHA), then, after showing that almost all existing aid concepts belong to the first class, focuses on IHA and tries to show that classical applications (that use a DHA approach) can be revised in a IHA fashion. The novel IHA systems produce different sensations, which in most cases may appear as exactly "opposite in sign" from the corresponding DHA; such sensations can provide valuable cues for the pilot, both in terms of performance improvement and "level of appreciation". Furthermore, the present dissertation shows that the novel IHA cueing algorithms, which were designed just to appear "natural" to the operator and not to directly help the pilot in the task (as in the DHA cases), can outperform the corresponding DHA systems.

Three case studies are selected: obstacle avoidance, wind gust rejection, and a combination of the two. For all the cases, DHA and IHA systems are designed and compared against baseline performance with no haptic aid. Both professional pilots and naive subjects were asked to test them through a deep campaign of experiments. Test results show that a net improvement in terms of performance is provided by employing the IHA cues instead of both the DHA cues or the visual cues only.

In the end, this thesis aim is to show that the IHA philosophy is a valid and promising alternative to the other commonly used, and published in the scientific literature, approaches which fall in the DHA category.

Finally the haptic cue for the obstacle avoidance task was tested in the presence of time delay in the communication link as in a classical bilateral teleoperation scheme. The Master was provided with an admittance controller and an observer of force exerted by the human on the stick was developed. Experiments have shown that the proposed system is capable of standing substantial communication delays.