Most people will probably have a typical image of a drone in their heads. It is usually a multi-copter type model, i.e. a device with many arms on the end of which is a propeller that together hold it in the air and allow it to fly and record the images for which it is so well known.
Now consider that same drone, but tethered to the ground with a string of, say, 50 to 100 metres, so that it can no longer perform the mission for which it was originally designed, which is to fly long distances while recording images with a camera.. This would seem to contravene the logic of its utility. However, by applying this restriction, the drone acquires a new dimension of use for which, a priori, one could not imagine that there is any practical use.
Captive drones have already proven their worth and are used in numerous direct applications that are currently being extensively exploited.
Having a drone tethered to the ground preventing it from realising its full potential in the activities for which it was created may seem counterintuitive but in practice, it provides mainly two features that when analysed in detail prove to be of considerable significance and usefulness.
These two main characteristics are:
- It has a physical element that connects it to the ground.
- It is severely limited in its movement.
Indeed, if we just look at it that way, such a drone makes no practical sense. What use can such a "handicapped" drone be?
Let's take a closer look at why these features make for interesting utilities:
The element that anchors the drone to the ground is a cable that can also conduct electricity and in cases where a normal drone has not been converted to a captive drone (i.e. the drone has been designed as a captive drone from the beginning) the cable also serves as a driving for control signals and data of the sensor embedded in the drone. Therefore, the main feature of being attached to the ground by a physical element gives the drone two new unique and tremendously exploitable "sub-features".
The first: allows it to be electrically powered indefinitely The captive system is a small battery pack that replaces the weight of the batteries with the weight of the cable (which is usually significantly less than the batteries) and therefore acquires much more flexible flight characteristics than in its non-captive configuration. This does not detract from the fact that most captive systems maintain a small emergency battery to provide a safe backup in the event of a cable power failure.
The second: control and sensor data do not need to be spread by radio frequency to be received by the operator, but can also travel over the cable..
The immediate result of the first "sub-characteristic" is that the drone is already no battery life limitation for flying. It can count on a virtually unlimited supply of energy and can therefore be kept in flight for as long as needed.
The immediate result of the second "sub-characteristic" is that it becomes virtually immune to external access or data theft because it simply does not broadcast any signals that can be tapped.
The second main characteristic (limitation of movement) also has several "sub-characteristics" of interest:
The system is inherently secure as there is no possibility of it flying out of control and causing damage to third parties. In principle, if the perimeter corresponding to the radius of the length of the cable is delimited or secured, the operation is completely safe as the operators themselves do not even need to be within the perimeter.
Additionally the operation is extremely simpleIf the vehicle is not in the specified height, there is no need to plan a time-consuming three-dimensional route with waypoints that may cross sensitive areas or overcoming obstacles. It only needs to climb to the specified height and remain in that position for the duration of the operation.
With all the features mentioned above, captive drones have already proven their worth and are employed in numerous direct applications that are currently being profusely exploited. In general, all of them the applications for which they are being used have the common denominator of needing a fixed observation camera at high altitude (or with a privileged viewpoint) for a relatively long time and with a quick and easy deployment.
Among the most common and widespread applications are safety applications, such as traffic surveillance in areas with high traffic density concentrated on specific days like weekends or holidays. With these systems, traffic authorities have a much clearer picture of the conflicts that are occurring, allowing them to act earlier to prevent and/or mitigate them.
At large sporting events or large gatherings of people, they are used by security services to allow continuous observation of critical areas both during the entire event and in the moments before and after the gathering and dissemination of the public.
In industrial applications, they have proven useful for engineering, insurance, safety and certification companies in damage inspections that require a relatively long time to survey structures that are difficult to reach, such as high building facades, bridges, wind generators, etc.
In the defence sector, they are used to maintain persistent surveillance from a forward observation point and undetectable in improvised areas.
In general, many other activities are welcoming this new technology because of its great usefulness and adaptability to the particular circumstances of the job at hand, combining high uptime with a highly safe operation.
The application of captive drones is now so well defined that the manufacturing industry counts this product speciality as a clearly separate range of solutions. of those in flight without physical restrictions due to their specialisation.
But that is not all. We have just seen new applications and new uses for drones that are not obvious at first glance when drastically limiting the possibility of movement of a system whose main application is precisely based on freedom of movement.
Now let's go one step further. Let's limit the drone's freedom of movement even further (instead of a cable of up to 100 metres, let's make it only 10 metres) and let's remove the video camera (which is another main attribute of these systems) ...what could be the use of a system that is not only lame, but also blind?
Incredible as it may seem, applications are already being explored and worked on that are only possible with such a "diminished" system ...these super-captive drones with a "short leash" and no camera are already being used in sports applications for towing people on surfboards, wakeboards, snowboards and skis with the advantage that, as before, the battery pack can be carried in a backpack on the adventurer's back when possible, drastically extending the autonomy of the equipment. These creations allow the surfer/wakeboarder to catch waves and jump without the need for a paddle or tow boat and for skiers/snowboarders it allows them to climb slopes without the need for a chairlift, to do backcountry sections and also to jump and negotiate obstacles. Of course it is still a very nascent practice that is unregulated and as such poses a relatively high risk, but patents have already been filed by major companies, there are numerous groups of enthusiasts testing variants and a number of initiatives have also been launched to start experimental demonstrations.
