"MAV Micro Drone" is the aerial lookout post of the US Army combat team. Plan for establishing the UAV team.

With the rapid development of technology and the rapid expansion of military needs, the number of drones, once regarded as battlefield luxuries, is rapidly increasing, and their application scope is also expanding. In the near future, U.S. Army combat squads will also have their own organic drones. This kind of micro-UAV is easy to carry and flexible to use. It can freely shuttle through neighborhood alleys and mountain valleys in urban and complex terrain environments. Tall buildings and undulating terrain can no longer block the soldiers' sight. Small drones will change the way we fight in the future. The MAV (Micro AirVehicle) vertical take-off and landing drone that the US Army is vigorously developing is a representative of the new generation of micro drones.

Arrived at the historic moment

Currently, the US military is engaged in a protracted unconventional war. The troops must not only be competent in high-intensity combat operations, but also be competent in a large number of non-war military operations. The battlefield environment is complex and changeable, and urban operations and complex terrain operations are new topics faced by the army. The "three-block operations" concept launched by the US military reflects the characteristics of urban operations under the new situation: in one block, peacekeeping and humanitarian assistance missions may be carried out; in another block, counter-guerrilla operations may be carried out; and in the third neighborhood, likely to engage in high-intensity conventional combat with well-trained troops.

Therefore, in a highly complex environment, troops must have a thorough understanding of the battlefield situation. In order to avoid friendly fire incidents, the US military requires troops to never take their sights away from the target when shooting. This is easier said than done in built-up cities and rugged mountains. Therefore, the US military urgently needs a drone that is easy for soldiers to carry, easy to take off and land, and can "hover and stare" at targets in the air. Although small UAVs have been widely equipped in the US military, they are basically fixed-wing UAVs. They require site support when taking off and landing, and the equipment level is high, making it difficult to provide timely support to combat teams.

To this end, the US military requires that combat teams be equipped with a micro-UAV for battlefield reconnaissance and surveillance. The main requirements for this UAV are: vertical take-off and landing: suitable for cities And an environment similar to the mountains of Afghanistan; the maximum flight altitude is 3,200 meters; easy to train and use; can complete takeoff, flight and landing independently; can identify human-sized targets (250 meters during the day, 125 meters at night); target positioning accuracy is 80 meters; Can be carried by personnel.

Under the auspices of the US Defense Advanced Research Projects Agency (DARPA), the micro-UAV advanced concept technology demonstration project was launched in September 2003. The purpose of the project is to determine the value of a man-supported ducted fan drone for use by ground combat teams.

The ducted fan drone is driven by a fan installed in the duct. The fan draws air in from the top of the duct and exhausts it from the bottom, creating thrust that allows the drone to take off, land and hover vertically like a helicopter. The reason why the US military chose the ducted fan UAV is mainly due to its ability to "hover and stare" at the target, and it can also fly close to buildings, which is very useful in urban combat.

MAV adopts a spiral advancement and phased development method, divided into Type 1 and Type 2 to gradually improve the performance of the system.

Type 1 MAV uses engines currently on the market. It passed the preliminary design review in March 2004, passed the critical design review in November 2004, and conducted its first tethered flight test in December 2004. The first formal untethered flight test was conducted in March 2005, and it passed the military acceptance test and safety review in July 2005. It conducted combat use tests at Fort Benning, Georgia, in August 2005, and was launched in Hawaii in October 2005. Trials for operational use were conducted at Cofield Barracks.

Because the US Army requires the Type 2 MAV to use heavy fuel engines. The existing miniaturization technology of heavy oil engines cannot meet this requirement, so while the Type 1 MAV is being developed, the development of heavy oil engines is also being carried out simultaneously.

In 2006, based on the results of the Type 1 MAV field evaluation, the development of the Type 2 system began.

In view of the fact that heavy oil engine technology is not yet mature, the Type 2 system prototype temporarily uses a gasoline engine to allow the development work to continue to move forward.

In May 2006, MAV was selected as the level 1 (platoon-level) UAV of the US Army's "Future Combat System" and is expected to be equipped with brigade combat teams from 2012 to 2014.

In October 2006, the Type 2 system passed the acceptance test and then began operational testing.

As of the end of 2006, MAY had successfully conducted 500 flight tests. During the flight test, MAY demonstrated its ability to fly and hover at an altitude of 152 meters above the ground in adverse weather conditions, navigate 8 kilometers with a single waypoint, and navigate multiple waypoints at short intervals. In addition, the day and night imaging technology of forward-looking and top-looking video sensors, sensor screen interception and storage technology, and the ability to fly close to buildings were also demonstrated.

System composition and performance

The MAV system was jointly developed by Honeywell and AAI. According to the current configuration plan, a MAV system includes 2 aircraft, 1 ground control system and related support equipment. Support equipment mainly includes batteries, fuel, fuel pumps, aircraft starters (one for each aircraft) and backpacks. The entire system weighs no more than 18 kilograms.

The aircraft is composed of a ducted fan body in the center and detachable instrument cabins on both sides. The avionics instrument bay contains batteries, avionics circuit boards and navigation sensors. The sensor cabin is equipped with a radio station, CPS receiver, forward-looking and top-view imaging sensors.

The aircraft is powered by a 4-horsepower gasoline engine. Flight control is via an autonomous flight stabilization and control system, which uses input from an inertial measurement unit and a GPS receiver to issue commands to the control surfaces. The control surface consists of four independently controlled square blades. The navigation accuracy of NAV is 10 meters for horizontal positioning and 4 meters for elevation. Equipped with an advanced navigation system, the MAV can provide high-precision target coordinates.

The aircraft is 33.02 centimeters tall and weighs about 8 kilograms after refueling. Its actual weight depends on a variety of factors, including fuel load, sensor weight, and the thrust and weight ratio required to ensure reliable flight control in adverse weather conditions and thin air. The maximum speed of the aircraft is 92.6 kilometers per hour, the climb speed is 7.3 meters per second, and the endurance time is more than 44 minutes (at an altitude of 1,676 meters). Under normal circumstances, the operating altitude of the aircraft is between 30.5 and 152 meters, and the maximum operating altitude is 3,200 meters.

The aircraft can adapt to harsh weather conditions such as rain, fog, and sandstorms. It can take off and land under wind speeds of 27.8 kilometers per hour, and can operate on rainy days (rainfall of 12.7 millimeters per hour) and wind speeds of up to 37 kilometers per hour. / hour flight conditions, operating temperature range -18 ℃ ~ 46 ℃, humidity is 100%.

MAV is equipped with two interchangeable sensor cabins, each equipped with photoelectric sensors and infrared sensors. The former has a recognition distance of 250 meters for human-sized targets, and the latter is 125 meters. Both are dual-sensor configurations, used for forward-looking reconnaissance and top-view reconnaissance respectively. Reconnaissance images are transmitted to the ground through a wireless communication system, and operators can observe simultaneously. The maximum image transmission distance is 10 kilometers. The aircraft can record video images for up to 10 minutes.

Ground Control System (GCS) The ground control system consists of a small laptop computer called an operations controller (OCU) and a ground data terminal (GDT). The ground data terminal is equipped with a GPS receiver, battery, radio station and antenna. The operation controller and the ground data terminal are connected through a USB interface. The operating controller comes with software for mission planning and high-level system control. There are no special requirements for operators in terms of aircraft piloting skills. Within a MAV autonomous flight plan, 100 waypoints can be preset. All waypoint settings can be completed with a simple touch on the screen interface at the ground station.

The ground station can pre-store up to 10 flight plans and input them into the aircraft during its flight. Flight planning software can provide a variety of preset cruise modes for developing flight plans. The ground control system can also record 60 minutes of sensor video images.

Easy to control

MAY’s take-off, landing and control procedures are designed with the starting point of ensuring the safety and security of soldiers. When in use, soldiers only need to first open the support legs of the aircraft, connect the instrument bays on both sides, place the aircraft on the ground, and then pull the pull rope, and the aircraft will start. The ground control system uploads the mission plan to the aircraft. From then on, the aircraft will operate completely autonomously until the mission is completed and the engine automatically shuts down. Currently, the refueling of the aircraft is done manually through a fuel injection pump, and the refueling operation can be carried out during the day and night.

In fact, the operator never implements true remote control of the MAV's flight. The aircraft flies according to a series of waypoints and/or flight modes according to preset programs. After the aircraft takes off, the operational controller is almost exclusively used to monitor images or the status of the aircraft. However, the operator can also intervene to control the sensor's field of view or change tasks during flight. At any moment during the flight, the operator can interrupt the flight mission and send instructions to the sensor to change the detection direction. The operator instructs the sensor to turn to a specific direction (up, down, left, right, front, back, clockwise, counterclockwise) by hand control, so that the front view or desired observation can be seen on the TV screen of the operating controller. Looking down at the image.

MAV can also be started and launched remotely, when the operating controller and the aircraft are placed in different locations. Once the aircraft reaches the predetermined flight altitude, soldiers at other locations equipped with operational controllers can take over by sending uplink commands, upload the flight mission plan and direct the MAV to perform the tasks that need to be completed.

Currently, operators can begin flying the MA~ system after receiving no more than 24 hours of training. There are no special military professional requirements to operate the system. During the trial, the 25th Infantry Division's MAV operators included infantrymen and scouts. An important conclusion drawn from the evaluation is that MAV does not require additional training for personnel in terms of aircraft control and data and image utilization. The initial training and test flights can be carried out at the military station. MAV is the organic equipment of the combat team in the true sense.

Improving day by day

In October 2005, an infantry platoon of the US 25th Infantry Division tested the Type 1 MAV at the urban combat base of Schofield Barracks. The test team tested the UAV's flight altitude, range, wind influence, take-off and landing methods, refueling methods, equipment packaging, and the performance of the forward-looking and top-view sensors working day and night. The device and graphical user interface as well as the long-distance video terminal have undergone extremely strict inspections.

In order to understand the military use of MAV, the infantry platoon performed a series of tasks with and without MAV, including route reconnaissance, regional reconnaissance, escort, and target attack. The test results were recorded using instruments to provide quantitative data for evaluation. The test force also conducted repeated contests with "hostile" forces, and discovered the advantages and disadvantages of MAV during the confrontation. During the confrontation, the "enemy" forces constantly changed their tactics, forcing the infantry platoon to constantly abandon traditional tactics and adopt new tactics, and had to abandon any "high ground" or exposed positions within the opponent's line of sight.

The initial assessment of the Type 1 system was positive. At the same time, the test force put forward suggestions for improving the MAV's starting method, navigation system, user interface, endurance, etc., and accumulated experience in personnel establishment, combat use methods, etc.

When the Type 2 MAV began to be developed, a large number of lessons learned from the Type 1 system were absorbed. Compared with the Type 1 system, the biggest improvement of the Type 2 system is to increase the fuel capacity and double the endurance time. In addition, all imaging sensors have been replaced.

These changes resulted in a structural redesign of the central ducted fan body and sensor bay.

In October 2006, the total number of 25 Type 2 MAV prototype systems was carried out by the reconnaissance platoon of the 2nd Brigade ("Stryker" Brigade) of the 25th Infantry Division at Schofield Barracks, Hawaii. After more than one month of rigorous testing. This exercise took the form of vehicle combat and dismounted combat. The test content includes urban terrain reconnaissance and clearing obstacles in buildings (on foot operations), route reconnaissance, regional reconnaissance and escort, etc. After evaluation, these MAV systems were retained by the 25th Infantry Division for further testing.

So far, the development of the US military's ducted fan micro-UAV has taken less than four years to complete the system design, testing and product upgrade from type 1 to type 2. This shows the urgency of the combat troops' demand for such micro-UAVs.

Currently, the U.S. Department of Defense Advanced Research Projects Agency is continuing to study improvements to MAV and is preparing to further expand its scope of military applications. It is expected that MAV will be potentially used in the navy's operations in coastal and river network areas. The improved MAV will be equipped with ground moving target display sensors to enhance situational awareness, and will also adopt a universal ground control system. This enables interoperability with other small UAVs such as the "Crow" and "Dragon Eye".