Unmanned aerial vehicles
UAV technologies appeared a long time ago. At first, they were complicated and expensive complexes of an exceptionally military application. However, the last ten years saw a real breakthrough in the field. As computing systems grew smaller and satellite navigation developed (GPS/GLONASS), it became possible to design unmanned aerial vehicles (UAVs) of a smaller size and weight and, more importantly, at a much lower cost. Today UAV technologies are almost as accessible as domestic appliances. With civil application of unmanned systems reaching the peak, we now have a new service industry.
UAVs are believed to be a promising solution to civil tasks involving dull, dirty or dangerous jobs, i.e. the tasks that are too monotonous or dangerous to be performed by a pilot of a piloted aircraft. There are good reasons for a growing demand in UAVs in different countries. The practice of using UAVs in leading states helped to identify a wide range of civil applications where UAVs proved to be highly effective.
There are several types of UAVs:
* unmanned uncontrolled;
* unmanned automatic;
* unmanned remotely piloted aircrafts (RPA).
UAVs are usually classified depending on their interacted parameters such as the weight, flight duration, distance and altitude. There are the following classes of UAVs:
* micro (conventional name) with the weight of up to 10 kg, the flight duration of about 1 hour and the altitude of up to 1 km;
* mini with the weight of up to 50 kg, the flight duration of several hours and the altitude of 3-5 km;
* midi with the weight of up to 1,000 kg, the flight duration of 10-12 hours and the altitude of up to 9-10 km;
* heavy with the altitude of up to 20 km and the flight duration of 24 hours and more.
Modern UAVs normally use navigational satellite receivers (GPS or GLONASS) for positioning and measuring the flight-path speed. To determine the orientation angles and overload, gyroscopes and accelerometers are used. The software is usually written in high-level languages such as C, C++, Modula-2, Oberon SA or Ada95. The typical hardware is specialized calculators based on digital signal processors or PC/104 or MicroPC computer format. Besides, real-time operating systems such as QNX, VME, VxWorks, XOberon can be used.
Unmanned aircrafts are designed to perform the following tasks:
- Aerial photography.
This is the most popular aerial function. There is vertical and oblique (panoramic) aerial photography. Vertical pictures are taken vertically in relation to the object being photographed. Panoramic pictures are taken at an angle to the horizon, resulting in a panoramic aerial view.
- Aerial video filming.
As a result of a higher resolution of modern video cameras and excellent image quality, unmanned aerial video filming is used as often as usual aerial photography. Then the film, if necessary, can be cut into separate shots with the most interesting ones being selected and used as separate aerial pictures. Aerial video filming is quite often used to make a nice account of important events and occasions as well as in advertisement. This is a chance to produce an exciting sportscast or to record a colourful show.
- Land plot planning.
Drawing up a land register is a difficult task that is much in demand. The use of a remotely controlled aircraft creates an opportunity of an effective low-cost solution of cadastral aerial photography. RCAs are often used to determine land plot borders or estimate construction costs. The choice of the shooting angle affects the visibility of the plot on the aerial photographs with regard to nearby water sources, forest areas, main traffic routes and junctions. The use of a UAV makes it possible to set the needed shooting angle and monitor the area being photographed from the air in the real-time mode on the external pilotís screen. This is the most effective way of ground marking for industrial or civil construction.
- Area patrolling.
The UAV can get off the ground, fly over the area following the set route with a video or photo camera on and return to the takeoff position in a robotic mode. If an intruder (a human being or a vehicle) is detected, either in the patrolled area or approaching to it, the UAV sends an alarm signal to the ground control station. The external pilot can assume control of the UAV at any point, take the necessary actions and get the UAV back to its tasks.
- Assistance in search and rescue.
It is difficult to overestimate the role of UAVs in search and rescue operations. They can give the necessary first-hand information support to rescue teams on the sea, in deserts, impenetrable swamps, natural or man-made disaster areas.
- Detection of objects.
A robotic aerial survey complex carries out the search, detection and identification of objects in the real-time mode. It determines their precise location with GPS or GLONASS and transmits the data to the ground control station. The objects of search can include: groups of people, individuals, vehicles, seats of fire, floods, real estate, bridges and other constructions. The complex can carry out the search and detection of objects both during the day and at night.
- Coordination of actions.
Continuous forest fire threat that has already resulted in significant financial losses, catastrophes, natural disasters and other emergency situations require effective technical aids to coordinate actions of rescue services. Such aids are remotely piloted aircrafts with the latest video cameras, thermal imagers and night vision cameras. The data obtained by the RCA is transmitted in the real-time mode to the ground control station, which makes it possible to coordinate actions of the ground forces.
- Work monitoring.
Sometimes it is necessary to control work progress, for example, when constructing a high-rise building. To walk to the top floors under construction and inspect the work will take quite a long time. A UAV with a video camera for aerial recording can do it within a few minutes. It can either fly around the building and archive the information or transmit the video in the real-time mode to the external pilotís display. UAV monitoring can be accomplished for the entire construction site or another area.
- Temperature control.
A robotic aerial complex with a thermal imager and pyrometer can maintain remote control of the reactor temperature at such sophisticated objects as atomic power plants. The vehicle can hover above the object and carry out a more detailed analysis, if necessary. At the remaining time the UAV can survey the plantís equipment in the patrolling mode following the set program.
- Toxic substances control.
At a lot of dangerous industries, even when the strictest safety standards are applied, emergency situations are within the realm of possibility, which can result in the discharge of toxic substances. To early detect them and alert the personnel, some companies now use super-light UAVs with sensors and gas analyzers. Aerial surveys and toxic substances control can be exercised in the automatic mode following the set route with a possibility of switching over to the semi-automatic control of the UAV. All the data obtained by the UAV sensors are permanently transmitted to the control station.
If communication between the UAV and the ground station is broken due to some reason, the return mode is on automatically, and the UAV goes back to the takeoff point for standard landing. If the communication is restored during the return flight, the external pilot can resume the task. Quick preparation for the UAV flight makes it possible to react promptly in any situation.
UAV operation is divided into the following stages:
- preliminary preparation;
- preflight preparation;
- flight operation (take off, en-route flight, landing);
- sea-level operations (data processing).
The preliminary preparation is carried out beforehand and includes:
- assessment of the forthcoming flight missions;
- coordination of the air-space exploitation with regional centers of the Unified Air Traffic Management System of the Russian Federation (regional centre of the Unified Air Traffic Management System of the Russian Federation is an operational unit of the Unified Air Traffic Management System of the Russian Federation dedicated to planning and coordination of the air-space exploitation, air-traffic management, ensuring of air-space exploitation licensing, monitoring compliance with the Russian Federation federal regulations of the use of the air space in a particular region of the Unified Air Traffic Management System);
- examination of the area where the work is planned, including land forms, location of natural and artificial obstacles;
- study of the flight rules and aeronavigation situation in the region of planned works, including location of aerodromes and landing grounds of air forces, presence of air routes, types of flights executed by aviation in the area of planed works;
- selection and preparation of cartographical documentation;
- specification of the peculiarities of UAV operations in particular conditions;
- establishing the external pilots cooperation order including situations of special occurrences;
- preselecting of takeoff and landing grounds with regard to the approach to them;
- task scheduling with fixing on the map (on the scheme of exploitation area) of all the peculiarities;
- patrolling route planning;
- establishing of the interaction order among different organizations participating in the operations (forest service, Ministry of Internal Affairs, Ministry of Emergency Situations, etc.).
Preflight preparation is carried out in the mission day and includes the performance of the following tasks:
- coordination of the flight;
- study of weather conditions in the flight area, possible actions in case of its deterioration;
- coordination of actions of the organizations involved (forest service, Ministry of Internal Affairs, etc.);
- flight mission planning (downloading of the air route into GCS (Ground Control System));
- specifying of the flying safety altitude;
- moving out into the working area, selection, examination and preparation of the launching pad (removing (trampling down) of grass, young growth, snow along the takeoff runaway);
- establishing communication with a regional centre of the Unified Air Traffic Management System, specifying (coordination) of the flight route (flying area), operational altitudes, the time of the beginning and end of the operation;
- deciding on the flight.
Obligatory stages of a UAV launch:
- establishing communication with a regional centre of the Unified Air Traffic Management System (itís forbidden to launch a UAV without establishing communication).
- examination of material equipment of the remote monitoring system and supplementary equipment;
- examination of their operability, including payload (video and photo cameras).
- examination of the actual weather conditions, including weather conditions along the flight route.
- a UAV is launched upwind in accordance with the Operational Manual.
- After the take-off, gaining the altitude can be executed either over the launch point on loop or by running out to the flight route.
- After the take-off, the external pilot makes a report to the regional centre of the Unified Air Traffic Management System on the take-off time, flight course, and the flight altitude of the UAV.
- After the altitude is gained, the flight of the UAV is executed automatically.
During the flight on the designated route, an external pilot, by controlling the video camera and changing the flying course of the UAV, carries out the following operations:
- examination of the location;
- object search in the location;
- object control in the location;
- characterization of the object;
- monitoring the flight parameters
- all the changes of the flight parameters (altitude, itinerary) are reported to the regional centre of the Unified Air Traffic Management System.
External pilot duties during the flight operation in video monitoring mode:
- target spotting(as a whole object);
- target recognition by a sufficient number of characteristic features (defining and fixing characteristic features of the target);
- verbal description of the target (e.g., Ďa forest fire spotí, Ďdamage area size and degree of damageí, Ďa carí, Ďa boatí, Ďa maní, etc.);
- registering the targetís location coordinates;
- target tracking and surveillance (video recording of the target within the mission time).
To perform video monitoring operations, the external pilot determines a preliminary flight path for the UAV according to the assigned mission and terrain characteristics. In standard algorithm of aerial surveillance or target search mode, the UA heads off to the surveillance field and follows the given mission scenario. During the flight within the assigned filed, the UAV transmits video images of the field and objects in it to the ground control station (GCS) in the real-time mode. The UAV external pilot classifies the incoming data, makes adjustments to the flying path, if needed, and controls an on-board payload (e.g., a camera-recorder).
The distinctive feature of the UAV surveillance is the possibility to approach the target or its separate elements repeatedly and focus the camera lens on the target for a specified period of time.
External pilot actions to perform the duties:
External pilot tasks upon spotting the target include:
- Target search− flying the UAV on a given path, where targets are expected to appear. Here the pilot monitors the terrain image transmitted from the UAV in the real-time mode.
- Target spotting−capturing the target by the instrumentation payload of the UAV (camera-recorder).
- steering the UAV on the target.
- changing the video monitoring mode(zooming, camera switching, etc.).
- changing the flight mode (altitude and speed loss, etc.).
- keeping the target in sight of the cameras (switching the UAV to the flyover, focusing, hovering mode, etc.).
- recognizing the target− referring the target to the certain kind (type), according to its visual characteristics and the pilotís experience. While recognizing the target, the pilot keeps on performing the same tasks as at its spotting. Having recognized the target, the pilot decides whether to include the target into the list of interest in a certain kind of objects.
- finding the target coordinates− fixing the targetís location in the geographic coordinate system using a satellite navigation system(GPS, GLONASS).The external pilot orders to the UAV control box to register the target coordinates.
It must be born in mind that the error in coordinate measuring of the target from the UAV coincides with the measuring error of its own coordinates.
- Report. The external pilot prepares a report based on the results of the work on the target, that later is passed to the customer, e.g., forest service personnel.
- Follow-up surveillance. When the work on the target is finished, the pilot decides on the following: orders to the UAV either to continue the given flight path or to make a second approach to the target; the pilot can also change the further flight path of the UAV.
- The landing of the UAV is performed according to its operational manual.
- If the weather is favorable and the landing area is more than 100ű100 meters, the UAV is capable of autonomous landing (as a rule), with the pilot controlling it visually.
- In case of a landing on a limited area or near the barrier line, water objects or weather deterioration, the pilot can land the UAV manually (in semiautomatic mode).
- After landing, the boarding time and the further work layout is reported to the Regional Air Movement Coordination Centre (RAMCC); a post-flight inspection of the UAV and preparation to the next flight (if necessary) is carried out.
After landing, photo and video data is collected from the GCS and the UAV and saved to the removable media. The data is examined and analyzed by specialists, and the further work layout is scheduled.
The remote monitoring package is complete with:
- In case of a communication failure with the UAV, the external pilot immediately reports to the RAMCC. The report must contain the time and location where the communication failure occurred, the altitude, estimated time-to-go and the flight route, the landing (crash) area of the UAV.
- In case of landing (crash) out of the targeted area, the search of the UAV is organized.
- If the UAV is stuck at the top of trees, the external pilot climbs the tree using the high-rise tool SPP-3, tethers the UAV, cutting down restraining the branches(if needed), and carefully takes the UAV down.
Customer package of the remote UAV may include the following monitoring instruments (payload):
- at least two aircrafts in protective wrapping (bags) weighting up to15-20kg., convenient for carrying in the field environment;
- ground control station with specially designed laptop (heavy duty, moisture- and dust-proof ). Minimum recommended: hard-drive space− 240 GB, system memory − 2 GB;
- transceiving aerial completed with an auto tracer and connecting cable;
- a mast and (or) rack for holding the transceiving aerial;
- a charging set (storage battery) completed with electric batteries or fuel supply for UAV engines;
- a launching platform: manual− rubber binder with a carbine (2 sets), and (or) mechanic (pneumatic) catapult;
- a set of spare parts and auxiliary equipment for minor repairing in the field environment;
- operational manuals, certificates and logbooks for the UAV, storage batteries and launching platforms.
- optical region video-recorders;
- infra-red (IR) band camera-recorders (infrared imager);
- optical band cameras;
- telephone link and wireless radio retransmitter;
- radar aids.
Video data from the UAV (camera-recorder or infrared imager) is transmitted through the radio channel to the ground control station (GCS). The data in the UAV is recorded to solid-state drive of a video recorder (SSD HDD or compact flash/SD card) or transmitted to the GCS where it is saved to the computer memory.