UAV systems have penetrated almost all areas of the battlefield space with their mobility, long-lasting flight and "zero casualties" characteristics. The outstanding performance of drones in recent local wars has attracted the attention of the military of various countries, especially military powers, and has become a key node and an important part of the information weapon equipment system. It is used in information support, information confrontation and firepower. Fighting and other fields play an irreplaceable role.

　　Compared with manned aircraft, the advantages of drones are mainly reflected in the following five aspects:

　　One is the ability to perform air missions for a long time;

　　The second is to replace manned aircraft into nuclear/bio/chemical and other polluted environments to perform tasks;

　　Third, there are no pilot casualties, and political and military risks are relatively small;

　　Fourth, because it does not consider human factors, it can withstand larger loads, and the stealth and maneuverability of the aircraft can achieve a qualitative leap;

　　Fifth, the life-span cost is low, and the combat efficiency-cost ratio is high. Compared with satellites, UAV systems have the advantages of timeliness, pertinence and flexibility.

　　The status and role of drones

　　Drones are an advantageous tool for seizing information rights

　　UAVs can provide long-term and lasting battlefield information support services, and can obtain battlefield information in real time. It has multi-dimensional integration, full coverage, continuous real-time, accurate and precise information perception capabilities; UAV systems of different types and different heights form a covered battlefield The information support network for communication, navigation and positioning from low altitude to adjacent space areas forms a flexible, maneuverable, multi-level, three-dimensional space-based and near-space-based comprehensive information support capability, which improves command efficiency and enhances joint operations Sex and flexibility.

　　Drone is an important pillar of future battlefield information confrontation

　　Information confrontation refers to the implementation of electronic interference, electronic deception, electronic decoys, cyber attacks, and anti-radiation destruction of the enemy's information system. Different types of UAV systems can meet the needs of multi-level information confrontation capabilities of strategy, campaign, and tactics, and can provide different types of information confrontation methods, ranging from tactical information confrontation support to strategic combat information confrontation. The combat capability of the enemy’s information system can achieve full-frequency, full-time, and all-weather information attacks on the enemy’s information system, forming a multi-level information combat force system framework.

　　Drones will become the dominant force in air operations

　　UAV will have the ability to detect and strike time-sensitive targets, accurately strike the enemy’s deep and important targets, approach space combat capabilities, and transatmospheric combat capabilities, and become the dominant force in air operations in the 21st century. In joint operations, unmanned combat aircraft can perform air defense suppression tasks and coordinate various forces to strike in depth on enemy territory; UAVs can coordinate with ground and sea forces to indicate targets and perform fire calibration for ground and sea weapons. Improve strike accuracy; UAVs can also perform combat assistance, battlefield management, theater missile defense, mine countermeasures, and psychological warfare.

　　Drone is the best choice for the most dangerous missions

　　The proportion of precision-guided weapons used in high-tech information warfare is increasing. Nuclear, biological, and chemical weapons coexist, and their lethality increases, and combatants will face great danger. Therefore, UAVs can replace manned aircraft to perform the most dangerous tasks, avoiding casualties to the greatest extent.

　　The technical basis of drones

　　The development of aviation technology is the basis for promoting the development of UAV technology. UAVs are aircraft that rely on aerodynamics to carry their flight. How to make UAVs able to fly stably and reliably with better performance depends on the application and development of aviation technology.

　　Aviation technology includes aerodynamics technology, flight dynamics technology, aviation structure technology, aviation material technology, aviation engine technology, flight control and navigation technology, avionics electrical and electronic technology, etc. The early development of aviation technology mainly solves the problem that drones and other aircraft can fly The development of modern aviation technology has promoted the development of UAVs in the direction of higher and higher flight performance, better and better flight reliability, and stronger and stronger ability to perform tasks.

　　The development of wireless data link technology is a condition to promote the development of UAVs to usability and practicality. Since UAVs are unmanned on board, they must rely on the ground control station to realize their control and flight status monitoring through wireless data links. Therefore, the wireless data link is the condition to promote UAVs to be usable and practical. The development of modern data link technology makes the UAV data link develop in the direction of high speed, broadband, confidentiality, anti-interception and anti-jamming capabilities, and promote the practical ability of UAVs to become stronger and stronger.

　　The main key technologies for the development of UAVs

　　The future development of drones in the direction of higher, faster, farther, more maneuvering and more efficient, the main key technologies needed are:

　　1, platform technology (comprehensive layout, pneumatic, lightweight structure, stealth);

　　2, large-size composite material design (standard), processing technology (cost);

　　3, structural composite materials, anti-ultraviolet materials, lightweight materials, high temperature resistant materials, etc.;

　　4, micro processing and assembly technology, application of smart materials (flexible wings without rudder surface, micro, bionic UAV);

　　5. Advanced launch and recovery technology;

　　6. ​​Miniaturization and integration of weapons and equipment;

　　7, stealth technology;

　　8. Power technology;

　　9, communication technology;

　　10, intelligent control technology;

　　11. Airspace management technology;

　　UAV flight control technology

　　Flight control and management system is one of the key systems of UAV. The flight control system is the core system for the drone to complete the entire flight process such as take-off (launch), air flight, mission execution, return landing (recovery), etc. It realizes full authority control and management of the drone, so the Function and performance play a key and decisive role. Without a flight control system, modern UAVs would not be able to fly into the sky and complete various tasks.

　　UAV flight control systems generally include three parts: sensors, onboard computers and servo actuation equipment.

　　Drone control mode

　　The flight control system of the UAV is full time limit and full authority, and the flight control mode can be divided into program control (time program control), remote control (controlled by remote command of the ground station) and autonomous flight control (two-dimensional, three-dimensional or four-dimensional) Three kinds.

　　The first two types of flight control methods are often used for the flight control of drones such as target drones and observation aircraft, and the third type is often used for the flight control of reconnaissance aircraft and attack aircraft.

　　In the remote control mode, the ground operator controls the drone's flight according to the status information and mission requirements of the drone;

　　In the autonomous control mode, the flight control system automatically controls the flight of the UAV based on the aircraft status information and mission planning information obtained by the sensors.

　　In the semi-autonomous control mode, the flight control system autonomously controls the flight of the UAV based on the aircraft status information and mission planning information obtained by the sensors on the one hand, and on the other hand, it receives remote control commands from the ground control station to change the flight status.

　　Airborne sensor

　　UAV flight control system commonly used sensors include angular rate sensor, attitude sensor, heading sensor, altitude airspeed sensor, aircraft position sensor, angle of attack sensor, overload sensor, etc. The selection of sensors should be carried out on the basis of the preliminary design and simulation of the control law according to the control needs of the actual system.

　　1, angular rate sensor

　　Angular rate sensor is one of the basic sensors of the flight control system. It is used to sense the rotation angular rate of the UAV around the body axis to form angular rate feedback, improve the damping characteristics of the system, and increase stability.

　　The choice of angular rate sensor should consider its measurement range, accuracy, output characteristics, bandwidth, etc.

　　The angular rate sensor should be installed near the center of gravity of the UAV, at the node of the first-order bending vibration, and the installation axis is parallel to the axis of the body to be sensed, and special attention should be paid to the correctness of the polarity.

　　2, attitude, heading sensor

　　The attitude sensor is used to sense the pitch and roll angle of the drone, and the heading sensor is used to sense the heading angle of the drone. Attitude and heading sensors are an important part of the UAV flight control system, which is used to achieve attitude and heading stabilization and control functions.

　　The choice of attitude and heading sensors should consider their measurement range, accuracy, output characteristics, dynamic characteristics, etc.

　　Attitude and heading sensors should be installed near the center of gravity of the aircraft, the vibration should be as small as possible, and the installation accuracy requirements should be higher.

　　For the magnetic heading sensor to be installed in a relatively fixed place where the influence of ferromagnetic materials is minimal, the installation parts should be made of non-magnetic materials.

　　3, altitude, airspeed sensor (or air data computer)

　　Altitude and airspeed sensors (or atmospheric data computers) are used to sense the flight altitude and airspeed of UAVs, and are necessary sensors for altitude and airspeed maintenance. Generally, the airspeed tube and the vent line constitute an air data system.

　　The selection of altitude and airspeed sensors mainly considers the measurement range and measurement accuracy. The installation is generally required to be near the airspeed tube, and the pipeline is as short as possible.

　　4, aircraft position sensor

　　Aircraft position sensor is used to sense the position of the aircraft, which is a necessary prerequisite for flight trajectory control. Inertial navigation equipment and GPS satellite navigation receivers are typical position sensors.

　　Aircraft position sensor selection generally considers navigation accuracy, cost, and availability related to flight time.

　　Inertial navigation equipment has installation location and higher installation accuracy requirements. The installation of GPS receiver should mainly avoid the problem of antenna occlusion.

　　boot device

　　Precise guidance is the basis for the automatic landing of UAVs. Due to the use of airstrips, it is obviously impossible to use general instrument landing systems or microwave landing systems. Under this premise, there are the following methods to choose from.

　　1) Global Positioning System (GPS): GPS is the navigation facility with the highest positioning accuracy so far, and it is widely used in countries all over the world. When GPS is used as a precision approach and landing guidance system, it must be combined with INS and radio altimeter. Because GPS is easily restricted by the United States, it should not be overly dependent on it.

　　2) Regional Positioning System (RPS): The Regional Positioning System (RPS) realizes the positioning of air targets by placing 4-6 devices (which can be called pseudolites) that are functionally equivalent to positioning satellites in a certain area on the ground.

　　3) Ground-assisted guidance facilities: The aircraft is positioned through the ground-based precision optical system or guided radar, and the positioning information is transmitted to the flight control computer by the uplink data link.

　　4) Visual guidance: Use the photoelectric equipment on the drone (which should be locked at a certain angle) to take real-time camera scenes and superimpose the drone's attitude, heading, airspeed, altitude and other information to form a similar image to a manned aircraft. The head-up display of the aircraft, combined with the visual results of the airport personnel on the drone, manually guide the aircraft to approach and land.

　　Servo mechanism

　　Servo actuation equipment is also called steering gear, which is the executive part of the flight control system. Its function is to receive flight control instructions, perform power amplification, and drive the rudder surface or engine throttle to deflect, so as to achieve the purpose of controlling the attitude and trajectory of the UAV.

　　Servo actuation equipment can be divided into electric servo actuation equipment, hydraulic servo actuation equipment and electro-hydraulic hybrid servo actuation equipment. Electric servo actuation equipment is usually used on drones.

　　flight control law

　　Flight control law is an important part of the flight control system. It is a mapping relationship between instructions and various external information to the aircraft's execution agencies. The design of the flight control law is to determine this mapping relationship, so that the aircraft has the flight quality that meets the system requirements in the entire flight envelope. The basis for the design of flight control law is the system development mission contract and related top-level technical documents. According to these documents, the various qualities or performances of the aircraft under the control system are specifically formed. Based on the analysis of the characteristics of the uncontrolled aircraft, in order to achieve the required flight quality or performance, the preliminary control law structure is determined, and then applied The design method of automatic control specifically determines the control law parameters. Through non-linear full-scale simulation, semi-physical simulation and flight test, verify or adjust the control law structure and parameters to make the flight quality or performance meet the requirements. The control law design process is an iterative regression process.

　　control law structure

　　First of all, the control surface of the aircraft should be clarified. The general control surface consists of elevators, ailerons, rudders, flaps, canards, speed brakes, etc. Determine the control law structure according to the performance requirements of the UAV and the characteristics of the uncontrolled UAV. Control law includes longitudinal control law and lateral control law. According to the mission requirements of the UAV, the following control law structure is selected.

　　Pitch angle stability and control

　　The pitch angle stability and control loop generally requires pitch angle and pitch angle velocity feedback signals, and the general control law structure is shown in the figure.

　　Rolling angle stability and control

　　The roll angle stability and control loop generally requires roll angle and roll angular velocity feedback signals. The general control law structure is shown in the figure.

　　Course stability and control

　　The general structure of heading angle stability and control is shown in the figure. Among them, the control structure uses ailerons for heading control, which has a high control efficiency, but the sideslip angle is relatively large in the control; using the rudder for heading control, this form of control efficiency is low, and the introduced roll angle feedback is used for part Eliminate sideslip angle; use the aileron and rudder to jointly control the heading angle, which has the characteristics of high control efficiency and small sideslip angle.

　　height control

　　Height control is composed of pitch inner loop and outer loop. The pitch inner loop is generally composed of pitch angle and pitch angular velocity feedback, and the outer loop for height control generally adopts the form of proportional + integral + differential, as shown in the figure.

　　Airspeed control

　　Airspeed control is divided into throttle airspeed control, pitch airspeed control and drag airspeed control. Throttle airspeed control realizes airspeed control by adjusting the engine throttle. Pitching airspeed control changes the angle of attack of the aircraft through elevator deflection, thereby changing the aerodynamics of the aircraft to achieve airspeed control, and drag airspeed control is changed by the deflection of the drag plate Resistance realizes airspeed control.

　　Because the engine generally has a large time delay, the throttle airspeed control is generally relatively slow, and the pitch airspeed control and drag airspeed control have the characteristics of relatively fast response.

　　lateral deviation control

　　Lateral deviation control can realize lateral track control. The lateral deviation control is generally realized through the roll control of the aircraft, which is composed of a roll inner loop and a sideways outer loop. The yaw distance is the distance relative to the desired route, that is, the difference between the desired route and the actual route. The difference control is generally used in the cruise flight phase, and the non-difference control is mainly used in the precise control phase, such as landing.

　　Lifting speed control

　　Lifting speed control is generally used in the leveling phase of automatic wheeled landing, and its control structure is composed of a pitch inner loop and a lifting speed outer loop, as shown in the figure.

　　UAV data link technology

　　Data link is one of the main components of UAV system. The design involves many technical fields such as remote control and telemetry, tracking and positioning, image transmission, microwave communication, satellite communication, anti-jamming communication, antenna servo, automatic control and computer application. It is a complex information system project.

　　Data link function

　　1, for drones and