Two main algorithms are presented to use an UAV for surveillance purposes. A very fast algorithm for the scan of an unknown area has been implemented and tested: it permits to scan a domain for the definition of layout, boundaries, obstacles : : : Once that the area has been acquired, a second algorithm is used to monitor the regions of interest in an efficient way. A neural network has been built in order to choose the shortest path to reach a determined point, giving the drone the possibility to avoid unexpected obstacles. Finally these two algorithms has been tested to verify their accuracy and speed.
IntroductionOver the last years, Unmanned Aerial Vehicles (UAV) have been applied in several interesting fields. The improvement and diffusion of control strategies both in terms of vibration suppression/stability [1] and path following [4] allowed to extend their application field. In this paper we propose to use a quadcopter for private, both domestic and industrial, surveillance purposes. The work begins with the implementation of an algorithm to scan an empty area: the UAV moves freely into given boundaries that have been identified from a sonar or laser camera, having the ability to avoid every kind of obstacle. Complete coverage path planning methods are many in literature. Already at the end of the 80s Lumelsky and Stepanov gave the idea of a complete sensor-based methods [5]. Neumann de Carvalho, Vidal, Viera, Ribeiro implemented a complete coverage path planning algorithm for a cleaning robot, but in their case the map of the area was a priori known [6]. In [7] Yang and Lao propose to scan the entire area by the implementation of a neural network.In this work we propose a simple and fast algorithm using the information received by the sensors mounted on the drone to scan the unknown area: this is filled with sparse obstacles (fixed or moving), added randomly all over the feasible surface. Our algorithm is thus able to identify boundaries and obstacles, and to avoid them.Moreover, pursuing the idea of security, the UAV should be forced to come back, after a given time, on regions that have been already scanned. Many articles has been written on this goal, achieving the result with genetic algorithms [8] and fuzzy logic approaches [9].However we focused our attention on the neural network approach, which seems the best compromise between speed and complexity requests, and which is a strengthened method for that kind of problems. One of the first attempts to apply a neural network in an industrial environment was proposed by Rivals, Canvas, Peronnaz, Dreyfus in [10], solving a complex automotive control problem using dynamical neural network models. Then Glasius, Komoda, Gielen in [11] tried to face a problem of path planning using a topologically organized neural network of a Hopifield type with nonlinear analog neurons. In terms of obstacle avoidance, a neural network model learning from human driving data is used by Djugash, Hammer in [12].Therefore, a pseudo-neural network was added to the mai...