Obstacle detection system (also known in the literature as sense and avoid, obstacle avoidance system (OASYS), obstacle collision avoidance and obstacle warning to name only a few), is used for any type of vehicles and applies to obstacles which are related to the said vehicle type and environment. For example, obstacle detection system for ground vehicles (manned and unmanned) may apply to obstacles such as (but not only) other vehicles, people, signposts, trees, fence, railing and pylons. Obstacle detection system for aerial vehicles (manned and unmanned) may apply to obstacles such as (but not only) other vehicles, suspended wires, point obstacles, pylons, antennas, trees, buildings and terrain features.
Commonly, obstacle detection system consists of four (or less) major parts:                a. Sensor: This is used to detect obstacles, either actively or passively, and may be, for example, a camera, acoustic sensor, laser radar (LADAR), radio-frequency (RF) radar, and more.        b. Signal processor: This may be either analog or digital, and is aiming at extracting, for each obstacle, a set of quantitative numbers describing each obstacle. For example, three (or less) coordinates fully (or partially) describing the position of the obstacle, velocity of the obstacles relatively to the system, reflection coefficient describing the structure of the obstacle, sensitivity to polarization describing the characteristic of the obstacle (e.g., wire or pylon), and more.        c. Obstacle map reconstruction (OMR): a method to interpret the data received from the signal processor, and to create an obstacles map or alert.        d. Path planning: This part (also known as automatic or autonomous maneuver device or system for example) is used to plan, represent and/or take principal driving directions within an environment while avoiding obstacles.        
Heretofore, various systems were devised to detect suspended wires, which form an obstacle for helicopters and for low flying light aircraft. Various wires include high voltage power cables, medium voltage cables, telephone cables and more.
Helicopters may collide with these wires, with fatal consequences. The problem is that it is difficult to see wires from the air, on the dark background of the ground. This is difficult at daytime in a good weather. It is impossible to see wires at night or in bad weather.
Suspended wires are more dangerous to helicopters than other ground obstacles. Ground obstacles usually have a relatively small width and height, whereas wires are located higher and span a large width, so the danger of collision with wires is much higher. Therefore, it is important to distinguish suspended wires from other ground reflectors and to warn the pilot accordingly.
US patent application 20110264303 of Lenser et al. illustrates a prior art method for improving situational awareness for teleoperation of a remote vehicle.
Prior art sensor systems apparently do not detect wires effectively. These include, for example, millimeter wave radar, laser radar, FLIR and more. These prior art systems are complex, heavy and costly and only achieve a limited success in detecting wires. There is a need for a light weight, simple structure system for wire detection and pilot warning.
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