A low-cost rocket-like recoverable test aircraft

Abstract

The present invention proposes a low-cost recoverable rocket-type test aircraft, which is used to realize flight test verification of various launch vehicle recovery algorithms and launch vehicle intelligent control algorithms. The aircraft's own structural design is simple, sturdy and easy to modify. The use of an aviation turbojet engine with adjustable thrust can achieve stable landing control when the rocket falls. The aircraft can achieve position and attitude movement of all six degrees of freedom through the power system and actuators. The control system equipped with the aircraft has strong computing power. Through the cooperation of the onboard flight control machine and the data processing computer with powerful computing power, it can realize the installation of medium-scale deep learning algorithm IP cores and the installation test of multi-core parallel algorithms. The aircraft flight control software is equipped with a fault-tolerant guidance law, which can be switched to the fault-tolerant guidance law to achieve safe flight of the aircraft when the aircraft test algorithm is out of control. At the same time, the emergency recovery device at the head of the aircraft can ensure the safe landing of the aircraft when the actuator fails.

Description

Technical Field

[0001] The invention relates to a low-cost rocket-like recoverable test aircraft, belonging to the field of aircraft design. Background Art

[0002] Reusable launch vehicles have become a hot topic in the current aerospace field because their reusable function greatly reduces the launch costs of space stations, satellites and other spacecraft. The intelligent flight control technology of launch vehicles is currently a new research direction in the field of aerospace control, and a reusable, low-cost aircraft is urgently needed to verify the relevant algorithms. Summary of the invention

[0003] The technical problem solved by the present invention is: to overcome the shortcomings of the prior art, to achieve rapid flight demonstration and verification of the vertical recovery control algorithm of the launch vehicle and the currently popular advanced intelligent control algorithm based on artificial intelligence, the present invention provides a low-cost rocket-like recoverable test aircraft for realizing the onboard flight verification of the advanced control algorithm and achieving safe fault-tolerant landing under the aircraft fault state.

[0004] The technical solution of the present invention is:

[0005] A low-cost rocket-like recoverable test aircraft, including: structural support, partition, take-off and landing system, power system, servo mechanism, ducted fan, rocket-borne flight control machine, inertial group, rocket-borne data processing computer, rocket-borne power supply system, emergency recovery device;

[0006] Pipes are used as the structural support of the aircraft. Multiple parallel circular partitions are set in the structural support for installing equipment. Rounded rectangular holes are opened on the partitions for equipment wiring. The partitions and pipes are connected by metal parts. Two threaded holes are opened near the partition on each pipe for installing ducted fans.

[0007] The aircraft shell is replaced by a plastic film package, and the aircraft shell is installed only when it is necessary to assess the control algorithm's ability to adapt to aircraft startup interference;

[0008] The take-off and landing system uses four-point support gas cylinder shock absorption;

[0009] The power system is installed at the lower part of the structural support to provide power;

[0010] The servo mechanism is installed on the structural support to realize the control of the engine swing spray direction;

[0011] Four ducted fans are installed on the waist of the aircraft through mounting brackets in an "X" shape to achieve the control of the aircraft's rolling freedom. The installation position can be adjusted through the threaded holes of the pipes.

[0012] The onboard flight controller is equipped with a basic flight control algorithm to realize the navigation solution, flight logic control and fault-tolerant flight control of the aircraft when the test algorithm fails. It is also equipped with a GPS module to realize the positioning of the aircraft.

[0013] Fiber optic inertial group is used to measure the acceleration and angular velocity of the aircraft;

[0014] The onboard data processing computer is used to load the algorithm to be verified;

[0015] The onboard power supply system is used to supply power to the aircraft's control devices, actuators, and power systems;

[0016] The emergency recovery device is installed inside the fairing to ensure a safe landing when the aircraft loses control.

[0017] Furthermore, the pipes and partitions are made of carbon fiber composite materials or aluminum alloys. When the partitions are made of composite materials, they have flanges on the edges. Eight hanging points are designed on the pipes to realize the suspension of the aircraft.

[0018] Furthermore, the take-off and landing system adopts a three-point landing gear, each point of which is connected to the aircraft structure support through a hinge and can swing to a certain extent; the landing gear includes a main support and a secondary support;

[0019] The main support adopts a carbon tube with an outer diameter of 25mm, an inner diameter of 22mm, and a thickness of 1.5mm; the secondary support adopts a combination of carbon tube + aluminum tube. The lower section of the secondary support adopts an aluminum tube with an outer diameter of 20mm, an inner diameter of 17mm, and a thickness of 1.5mm, and the upper section of the secondary support adopts a carbon tube of the same specification. An aluminum tube with an outer diameter of 17mm, an inner diameter of 14mm, and a thickness of 1.5 is inserted between the upper and lower sections and riveted into an integral secondary support.

[0020] Furthermore, the maximum thrust of the engine of the aircraft power system is 550N, and the engine can achieve a thrust-to-weight ratio of more than 1.5 for a 35kg rocket body in a full fuel state; the aircraft fuel tank has a fuel storage capacity of 8kg, which guarantees a maximum thrust flight time of 6.06min for the rocket body in a full fuel state;

[0021] The bottom of the aircraft's fuel tank is conical to prevent dead oil from being unused; the fuel tank is a soft tank with a refueling nozzle, a fuel supply nozzle, and an air vent.

[0022] Furthermore, the aircraft servo mechanism adopts the form of servo steering gear plus transmission gear. The two steering gears control the deflection of the engine in two directions respectively without interfering with each other. The transmission gear ratio is 3.5;

[0023] The servo mechanism can control the engine to deflect 10 degrees in both the front and rear and left and right directions;

[0024] The engine uses an annular bracket, which is connected to the load-bearing frame through bearings, and then transmits thrust to the rocket body structure support through lifting ears; the two servos are independent of each other in movement and uncoupled, controlling the engine to deflect in any direction.

[0025] Furthermore, four electric ducted fans are evenly arranged on the outside of the rocket body structure support and installed orthogonally.

[0026] Furthermore, the flight controller on board the rocket is equipped with a hardware floating-point unit, integrated with DSP instructions, and controls the engine, servo and ducted fan through a 16-channel PWM output interface;

[0027] The arrow-borne flight controller integrates a wireless data link with a transmission power of 1W, a maximum baud rate of 115200, and a range of 60km. It is directly connected to the servo control line to realize remote control of the aircraft through the aircraft model remote controller.

[0028] The onboard flight controller is integrated with a 4GB TF card memory, which stores data at a rate of 512Bytes / 10ms and can save more than 12 hours of flight data for easy post-flight analysis and diagnosis.

[0029] The Arrow-borne flight controller is equipped with an integrated GPS board.

[0030] Furthermore, the aircraft inertial group adopts a fiber optic gyro strapdown inertial group to measure the angular velocity and linear acceleration of the carrier's motion, and to compensate for temperature, installation misalignment angle, nonlinearity, and zero position errors.

[0031] Furthermore, an emergency recovery parachute is arranged in the top fairing of the aircraft as an emergency recovery device to ensure a smooth landing of the aircraft in case of an emergency. The deployment area of ​​the emergency recovery parachute is 12m 2 In a stable state, the aircraft's landing speed is 6-7m / s; a parachute buzzer alarm device is installed on the lower surface of the bottom of the parachute cabin. When the parachute is opened in the air, a 100-120dB alarm sound is emitted to warn ground personnel to stay away.

[0032] Furthermore, the onboard flight controller achieves aircraft control through the following methods:

[0033] (1) After receiving the ignition command from the ground, the attitude control network parameters are initialized and the initial position parameters are calculated based on the measured inertial group and GPS information;

[0034] (2) Until the takeoff command from the ground is received, the initial increment calculation of the aircraft inertia group and the initial attitude calculation of the rocket body are continuously performed to determine the initial attitude before takeoff;

[0035] (3) After receiving the takeoff command from the ground, the aircraft performs the inertial group output increment calculation, strapdown system solution, inertial group information navigation calculation and integrated navigation calculation in sequence according to the inertial group information and GPS information to complete the navigation process of a single control cycle and determine the current position, speed, attitude and attitude angular velocity of the aircraft;

[0036] (4) Perform guidance calculations based on the mission trajectory and the current aircraft state. If the aircraft position error is greater than a threshold, switch to fault-tolerant guidance law calculations. Otherwise, continue to use the test guidance law to obtain the aircraft thrust command and program angle command.

[0037] (5) Controlling the aircraft attitude according to the aircraft program angle, performing program angle filtering, attitude deviation calculation, attitude control system parameter calculation, attitude control equation solution, rudder output command and fan output command decomposition and limiting in sequence;

[0038] (6) Outputting PWM commands of aircraft thrust to the engine, aircraft pitch and yaw commands to two servos, and flight fan control commands to four ducted fans to achieve flight control of the aircraft;

[0039] (7) If the flight mission is completed, go to (8); otherwise, when the next control cycle begins, go to (3);

[0040] (8) End the flight and shut down the engine.

[0041] The beneficial effects of the present invention compared with the prior art are:

[0042] (1) The rocket body uses aviation kerosene as fuel, which can realize low-cost flight control of the rocket and can be reused. The fuel consumption of a single flight scenario is no more than 8L, and the cost of a single flight verification is only about 100 yuan.

[0043] (2) The rocket is light in weight, weighing only 27 kg without fuel, and can be carried by an adult. The rocket structure is designed to facilitate rapid disassembly and modification, and the engine can be replaced within 30 minutes, with an interval of no more than 15 minutes between two flight tests.

[0044] (3) The rocket body control system is equipped with a high-performance data processing computer that can realize the testing of algorithms such as the launch vehicle vertical recovery control algorithm and advanced intelligent control algorithm.

[0045] (4) A fault-tolerant control algorithm is designed for the rocket body and a safety parachute is provided to ensure safe landing of the rocket body in the event of a fault. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 It is a schematic diagram of the structure of a low-cost rocket-like aircraft;

[0047] Figure 2 This is the circuit diagram of the electrical control system on the arrow;

[0048] Figure 3 It is a schematic diagram of the layout of the servo drive mechanism and the ducted fan;

[0049] Figure 4 Arrange a position for the emergency recovery parachute;

[0050] Figure 5 Calculate flow chart for flight control;

[0051] Figure 6 It is a schematic diagram of the position control effect of a rocket-like aircraft;

[0052] Figure 7 Schematic diagram of the attitude control effect of a rocket-like vehicle. DETAILED DESCRIPTION

[0053] The specific embodiments of the present invention are further described in detail below with reference to the accompanying drawings.

[0054] The present invention proposes a low-cost recyclable rocket-type test aircraft, which is used to realize flight test verification of various launch vehicle recovery algorithms and launch vehicle intelligent control algorithms. The aircraft itself has a simple, strong and easy-to-modify structural design, uses aluminum rods or composite fiber materials to design the rocket body structure and landing gear, uses a thrust-adjustable turbojet engine as the aircraft power system, uses a steering gear and a ducted fan as the aircraft's actuator, and the control system is equipped with a flight control machine, an inertial group and a GPS receiver.

[0055] The aircraft of the present invention adopts an aviation turbojet engine with adjustable thrust to achieve stable landing control when the rocket falls, and the aircraft can achieve position and attitude movement of all six degrees of freedom through the power system and the actuator. The control system equipped with the aircraft has strong computing power. Through the cooperation of the onboard flight control machine and the data processing computer with strong computing power, it can realize the installation of medium-scale deep learning algorithm IP cores and the installation test of multi-core parallel algorithms. The aircraft flight control software is equipped with a fault-tolerant guidance law, which can be switched to the fault-tolerant guidance law to achieve safe flight of the aircraft when the aircraft test algorithm is out of control. At the same time, the emergency recovery device at the head of the aircraft can ensure the safe landing of the aircraft when the actuator fails.

[0056] The aircraft design of the present invention mainly has the following characteristics:

[0057] (1) The rocket body adopts a detachable modular design, which makes the rocket body easy to disassemble and repair.

[0058] (2) The rocket body engine uses an aviation turbojet engine with adjustable thrust, which is used to achieve the flight and vertical recovery of the rocket body, ensuring that the rocket body can be reused. The actuator can provide a large control margin relative to the rocket body.

[0059] (3) PWM signals are used to control all actuators of the entire rocket. At the same time, high-performance computers, high-precision inertial groups, and high-precision differential GPS are used to assist the aircraft in achieving high-precision control.

[0060] (4) The rocket body is equipped with a protective umbrella device, and a fault-tolerant algorithm is designed in the basic control software to achieve safe recovery of the rocket body under fault conditions and ensure the reuse of the rocket body.

[0061] Technical indicators of the aircraft of the present invention:

[0062] The flight time at maximum thrust is not less than 5 minutes;

[0063] Thrust-to-weight ratio not less than 1.5 (without test load);

[0064] The engine’s deflection angle range is not less than ±10°;

[0065] The preparation time between two flights under the same operating conditions shall not exceed 20 minutes;

[0066] The time for replacing an engine with the same specification shall not exceed 30 minutes.

[0067] like Figure 1 , 2 As shown, the present invention proposes a low-cost rocket-like recoverable test aircraft, including: structural support, partition, take-off and landing system, power system, servo mechanism, ducted fan, rocket-borne flight control machine, inertial group, rocket-borne data processing computer, rocket-borne power supply system, emergency recovery device;

[0068] Pipes are used as the structural support of the aircraft, and multiple parallel circular partitions are set in the structural support for installing equipment; rounded rectangular holes are opened on the partitions to facilitate equipment wiring; the partitions and pipes are connected by metal parts;

[0069] The aircraft shell is replaced by a plastic film package, and the aircraft shell is installed only when it is necessary to assess the control algorithm's ability to adapt to aircraft startup interference;

[0070] The take-off and landing system uses four-point support gas cylinder shock absorption;

[0071] The power system is installed at the lower part of the structural support to provide power;

[0072] Two servo steering gears are installed on both sides of the engine mounting bracket in a cross-shaped arrangement to control the direction of the engine jet swing;

[0073] Four ducted fans are installed on the waist of the aircraft through mounting brackets in an "X" shape to achieve the control of the aircraft's rolling freedom. The installation position can be adjusted through the threaded holes of the pipes.

[0074] The onboard flight controller is equipped with a basic flight control algorithm to realize the navigation solution, flight logic control and fault-tolerant flight control of the aircraft when the test algorithm fails. It is also equipped with a GPS module to realize the positioning of the aircraft. It is installed on the second layer of the aircraft by screws or Velcro by default (the order of the partition number is Figure 1 The right figure is numbered from top to bottom, the same below), the installation position can be adjusted;

[0075] The fiber optic inertial group is used to measure the acceleration and angular velocity of the aircraft. It is horizontally installed at the fixed installation hole of the second layer of the aircraft partition by screws;

[0076] The onboard data processing computer is used to implement the high-computing-power control algorithm. It is installed on the third-layer bulkhead of the aircraft by screws or Velcro by default, and the installation position can be adjusted.

[0077] The onboard power supply system is used to realize the power supply of various control devices, actuators and power systems of the aircraft. It is installed on the fifth-layer partition of the aircraft by Velcro by default. The installation position can be adjusted according to the cable length.

[0078] The emergency recovery device is installed inside the fairing to ensure a safe landing when the aircraft loses control.

[0079] The following is a detailed introduction to each component:

[0080] 1. Rocket body structure

[0081] The platform body adopts a high-strength epoxy resin-carbon fiber composite material structure by default. It can be replaced with a 7075 aluminum alloy body structure according to different flight test requirements. The selected composite materials and aluminum alloy materials have good mechanical properties and stable chemical properties. Aluminum alloy materials have good processability. Metal materials are used in key connection parts and concentrated load-bearing structures, and the take-off and landing system adopts four-point support cylinder shock absorption.

[0082] A pipe with an outer diameter of 25mm, an inner diameter of 22mm, and a wall thickness of 1.5mm is selected as the structural support. The partition is designed as a circular partition with a diameter of 350mm and a thickness of 2mm, which is used for the equipment installation surface. The partitions are opened with a circle with a diameter of 20mm and a rounded rectangle of 60mm×20mm to facilitate equipment routing. The partitions and pipes are connected by metal parts. The pipes and plates are made of carbon fiber composite materials. According to different test requirements, the equipment mounting plates or pipes can be replaced with 7075 aluminum alloy to reduce the stiffness of the arrow body and meet the special needs of elastic modal identification. When the partition is made of composite materials, it has a flange on the edge. In order to carry out low-altitude hovering tests under hanging protection, 8 hanging points are designed on the pipe to realize the suspension of the aircraft.

[0083] The outer shell is mainly packaged with plastic film, which is easy to disassemble and replace. The aircraft shell is only installed when it is necessary to assess the control algorithm's ability to adapt to aircraft startup interference.

[0084] The landing gear adopts a three-point landing gear, each point is connected to the arrow body through a hinge, and can swing to a certain extent. The main support adopts a carbon tube with an outer diameter of 25mm, an inner diameter of 22mm, and a thickness of 1.5mm. The secondary support adopts a combination of carbon tube + aluminum tube. The lower section adopts an aluminum tube with an outer diameter of 20mm, an inner diameter of 17mm, and a thickness of 1.5mm. The upper section adopts a carbon tube of the same specification. An aluminum tube with an outer diameter of 17mm, an inner diameter of 14mm, and a thickness of 1.5 is inserted between the upper and lower sections and riveted into a whole. The combination design of aluminum + carbon can meet the requirements of strength and lightness, and resist engine tail flame ablation.

[0085] 2. Power system and actuator.

[0086] The aircraft power system uses the JetCat P550-PRO-GL engine and supporting ECU. The maximum thrust of the bench test is 550N. The engine has stable performance and high reliability. For a 35kg rocket body with full fuel, it can achieve a thrust-to-weight ratio of more than 1.5. The aircraft fuel tank has a fuel storage capacity of 8kg, which can guarantee a maximum thrust flight time of 6.06min for the rocket body with full fuel. The bottom of the fuel tank is made into a cone to prevent dead oil from being unused. The fuel tank is a soft fuel tank that can suppress shaking to a certain extent. The fuel tank is equipped with a refueling nozzle, a fuel supply nozzle, and an air vent. A reliable oil circuit connection method is designed to ensure that the fuel can be stably supplied within the full envelope of the flight platform.

[0087] The aircraft servo mechanism adopts the form of servo steering gear plus transmission gear, such as Figure 3 As shown in (a), the two servos control the deflection of the engine in two directions respectively without interfering with each other. The gear ratio is 3.5. This structure can control the engine to deflect by 10 degrees in the front and rear and left and right directions. The engine adopts an annular bracket, which is connected to the load-bearing frame through bearings, and then transmits thrust to the rocket body through the lifting lugs. The two servos are independent of each other in action and are not coupled with each other, so as to achieve the effect of controlling the deflection of the engine in any direction. The downward movement of the engine shaft can significantly reduce the rotational inertia of the swinging part, increase the control arm, and obtain a greater control torque. During the design, 3D simulation is used to ensure that there will be no interference under the condition of ±10° deflection of the two axes. The design of this mechanism ensures that the installer can replace the engine of the same size within 30 minutes.

[0088] like Figure 3As shown in (b), four electric ducted fans are arranged on the rocket body, mainly to provide rolling control torque. The fan diameter is 50mm, the maximum voltage is 16.8V, the maximum current is 40A, the maximum thrust is 950g, the full load power is 670W, the total weight of the duct is 77g, and it is installed orthogonally. The duct frame adopts a plug-in installation method and can be installed on different layers of equipment cabins according to requirements, which is convenient for the removal and replacement of the ducted fan.

[0089] 3. Electrical and control systems

[0090] The flight controller on the arrow is small, low-cost and easy to maintain. The flight controller on the arrow adopts the STM32F407 processor, which has rich peripheral interfaces, strong scalability and high reliability. It has a hardware floating-point unit, integrated DSP instructions and powerful floating-point computing capabilities. The control of the engine, servo and ducted fan is realized through the 16-way PWM output interface. The device can integrate a wireless data link with a transmission power of 1W, a maximum baud rate of 115200 and a range of up to 60km. It can be directly connected to the servo control line through a standard Futaba connector, and the aircraft can be remotely controlled through the model aircraft remote control. The controller integrates a 4GB TF card memory, which can store at a rate of 512Bytes / 10ms and save more than 12 hours of flight data, which is convenient for post-flight analysis and diagnosis. It integrates Novatel high-precision GPS board with a high update rate to ensure fast and accurate positioning information; through the correction of the ground differential station, the positioning accuracy can reach the centimeter level. The weight of the whole machine is only 436g, which has little effect on the center of mass of the aircraft.

[0091] The aircraft inertial group uses a PN132 fiber optic gyro strapdown inertial group, which is an inertial sensor product developed for tactical military systems. It consists of three all-solid-state fiber optic gyros, three quartz flexible accelerometers, a data packaging board, a main body structure and related software. It measures the angular velocity and linear acceleration of the carrier's motion and compensates for errors such as temperature, installation misalignment angle, nonlinearity, and zero position. The gyro of this inertial group has a zero bias stability and zero bias repeatability of no more than 1° / h, and the accelerometer has a zero stability of no more than ≤300ppm and a zero bias repeatability of no more than 5×10 -4 The zero bias repeatability of g can assist in achieving high-precision position and attitude control.

[0092] The onboard data processing computer adopts TMS320C6678 and FPGAXCZU15EG to design the core architecture, which can realize large-scale high-performance computing of the aircraft and support the implementation of various intelligent algorithms.

[0093] The power supply system on the arrow uses Redzone series model aircraft batteries, which can power the aircraft engine, servo and control system for more than 20 minutes, meeting the full flight needs of the aircraft.

[0094] 4. Emergency recovery device

[0095] like Figure 4 As shown in the figure, an emergency recovery parachute is arranged on the top of the rocket body, which can ensure that the flight platform lands as smoothly as possible in an emergency and reduce the damage to the main body of the flight platform. The deployment area of ​​the emergency recovery parachute is about 12m2, and the landing speed of the aircraft is about 6-7m / s in a stable state. An umbrella buzzer alarm device is installed on the lower surface of the bottom of the parachute cabin. When the parachute is opened in the air, a 100-120dB alarm sound is emitted to warn ground personnel to stay away.

[0096] 5. Ground Control System

[0097] The ground station is small in size, light in weight and easy to integrate. It integrates a wireless data link with a transmission power of 1W and a range of up to 60km, which can support long-distance flight of the aircraft. It supports FUTABA remote control integration and can collect remote control signals (SBUS, PPM). It integrates a high-precision differential GPS base station to achieve centimeter-level high-precision positioning of the aircraft.

[0098] 6. Flight control process and fault-tolerant guidance law algorithm

[0099] The onboard flight controller achieves aircraft control through the following methods:

[0100] (1) After receiving the ignition command from the ground, the attitude control network parameters are initialized and the initial position parameters are calculated based on the measured inertial group and GPS information;

[0101] (2) Until the takeoff command from the ground is received, the initial increment calculation of the aircraft inertia group and the initial attitude calculation of the rocket body are continuously performed to determine the initial attitude before takeoff;

[0102] (3) After receiving the takeoff command from the ground, the aircraft performs the inertial group output increment calculation, strapdown system solution, inertial group information navigation calculation and integrated navigation calculation in sequence according to the inertial group information and GPS information to complete the navigation process of a single control cycle and determine the current position, speed, attitude and attitude angular velocity of the aircraft;

[0103] (4) Perform guidance calculations based on the mission trajectory and the current aircraft state. If the aircraft position error is greater than a threshold, switch to fault-tolerant guidance law calculations. Otherwise, continue to use the test guidance law to obtain the aircraft thrust command and program angle command.

[0104] (5) Controlling the aircraft attitude according to the aircraft program angle, performing program angle filtering, attitude deviation calculation, attitude control system parameter calculation, attitude control equation solution, rudder output command and fan output command decomposition and limiting in sequence;

[0105] (6) Outputting PWM commands of aircraft thrust to the engine, aircraft pitch and yaw commands to two servos, and flight fan control commands to four ducted fans, thereby controlling the aircraft for flight control;

[0106] (7) If the flight mission is completed, go to (8); otherwise, when the next control cycle begins, go to (3);

[0107] (8) End the flight and shut down the engine.

[0108] The specific flight control process is as follows: Figure 5 The guidance law and control law mentioned in the above process are determined according to the application requirements of the specific flight mission.

[0109] The aircraft is equipped with a set of fault-tolerant guidance laws inside the onboard flight controller, which is used to realize the flight control of the aircraft during the debugging process and the fault-tolerant flight control when the verification algorithm fails. The fault-tolerant guidance law is mainly based on the PID control law to realize the flight control of the aircraft. When the aircraft verification algorithm fails, the failure handover condition can be designed. If the condition is triggered, it switches to the fault-tolerant guidance law to achieve a smooth landing of the aircraft.

[0110] According to the fault-tolerant guidance law, the calculation specifically includes the following steps:

[0111] (1) Based on the current position P x0 The position of the handover point is given The natural frequency ω of the corrected trajectory is calculated as follows:

[0112]

[0113] (2) Take the position change in the X direction as the second-order inertia link of the given change, that is:

[0114]

[0115] Where ξ=0.7 is the damping ratio.

[0116] (3) Take the expected initial value of the given correction track as:

[0117]

[0118] Where P x_init ,V x_init It is the position speed in X direction during shift change.

[0119] (4) Calculate the given position and given speed of the aircraft to obtain the expected position value at time t Speed ​​Expectation Expected value of acceleration for:

[0120]

[0121] Δt is the step size of a single control cycle.

[0122] (5) When and When , the rocket's orbit is considered to have returned to normal, and the calculations based on the above formula are stopped, and calculations are performed based on the trajectory and guidance algorithms in the normal orbit.

[0123] 7. Flight test

[0124] The aircraft was tested several times in the suspended state. The aircraft hovered at a low altitude of 5m for 60 seconds and then landed vertically for recovery. Some intelligent algorithms were also carried out for verification. During the test, the aircraft worked normally and all algorithms were verified. The test results are as follows: Figure 6 and Figure 7 As shown, Figure 6 is the position control curve of the aircraft (Px, Py, Pz are the positions under the x, y, z coordinate axes respectively), Figure 7 is the attitude curve of the aircraft (Phi, Psi, Gam are pitch angle, yaw angle and roll angle respectively).

[0125] Parts of the present invention that are not described in detail belong to common knowledge among those skilled in the art.

Claims

1. A low-cost rocket-like recoverable test aircraft, characterized in that include: Structural support, partitions, take-off and landing systems, power systems, servo mechanisms, ducted fans, onboard flight control machines, inertial control groups, onboard data processing computers, onboard power supply systems, and emergency recovery devices; Pipes are used as the structural support of the aircraft. Multiple parallel circular partitions are set in the structural support for installing equipment. Rounded rectangular holes are opened on the partitions for equipment wiring. The partitions and pipes are connected by metal parts. Two threaded holes are opened near the partition on each pipe for installing ducted fans. The aircraft shell is replaced by a plastic film package, and the aircraft shell is installed only when it is necessary to assess the control algorithm's ability to adapt to aircraft startup interference; The take-off and landing system uses four-point support gas cylinder shock absorption; The power system is installed at the lower part of the structural support to provide power; The servo mechanism is installed on the structural support to realize the control of the engine swing spray direction; Four ducted fans are installed on the waist of the aircraft through mounting brackets in an "X" shape to control the rolling freedom of the aircraft. The installation position can be adjusted through the threaded holes of the pipes. The onboard flight controller is equipped with a basic flight control algorithm to realize the navigation solution, flight logic control and fault-tolerant flight control of the aircraft when the test algorithm fails. It is also equipped with a GPS module to realize the positioning of the aircraft. Fiber optic inertial group is used to measure the acceleration and angular velocity of the aircraft; The onboard data processing computer is used to load the algorithm to be verified; The onboard power supply system is used to supply power to the aircraft's control devices, actuators, and power systems; The emergency recovery device is installed inside the fairing to ensure a safe landing when the aircraft loses control.

2. A low-cost rocket-like recoverable test aircraft according to claim 1, characterized in that: The pipes and partitions are made of carbon fiber composite materials or aluminum alloy. When the partitions are made of composite materials, they have flanges on the edges. 8 hanging points are designed on the pipes to realize the suspension of the aircraft.

3. A low-cost rocket-like recoverable test aircraft according to claim 1, characterized in that: The take-off and landing system uses a three-point landing gear, each point of which is connected to the aircraft structure support through a hinge and can swing to a certain extent; the landing gear includes a main support and a secondary support; The main support adopts a carbon tube with an outer diameter of 25mm, an inner diameter of 22mm, and a thickness of 1.5mm; the secondary support adopts a combination of carbon tube + aluminum tube. The lower section of the secondary support adopts an aluminum tube with an outer diameter of 20mm, an inner diameter of 17mm, and a thickness of 1.5mm, and the upper section of the secondary support adopts a carbon tube of the same specification. An aluminum tube with an outer diameter of 17mm, an inner diameter of 14mm, and a thickness of 1.5 is inserted between the upper and lower sections and riveted into an integral secondary support.

4. A low-cost rocket-like recoverable test aircraft according to claim 1, characterized in that: The maximum thrust of the engine of the aircraft power system is 550N, and the engine can achieve a thrust-to-weight ratio of more than 1.5 for a 35kg rocket body in a full fuel state; the aircraft fuel tank has a fuel storage capacity of 8kg, which can ensure a maximum thrust flight time of 6.06min for the rocket body in a full fuel state; The bottom of the aircraft's fuel tank is conical to prevent dead oil from being unused; the fuel tank is a soft tank with a refueling nozzle, a fuel supply nozzle, and an air vent.

5. The low-cost rocket-like recoverable test aircraft according to claim 1, characterized in that: The aircraft servo mechanism adopts the form of servo steering gear and transmission gear. The two steering gears control the deflection of the engine in two directions respectively without interfering with each other; the transmission gear ratio is 3.5; The servo mechanism can control the engine to deflect 10 degrees in both the front and rear and left and right directions; The engine uses an annular bracket, which is connected to the load-bearing frame through bearings, and then transmits thrust to the rocket body structure support through lifting ears; the two servos are independent of each other in movement and uncoupled, controlling the engine to deflect in any direction.

6. A low-cost rocket-like recoverable test aircraft according to claim 1, characterized in that: Four electric ducted fans are evenly arranged on the outside of the rocket body structure support and installed orthogonally.

7. A low-cost rocket-like recoverable test aircraft according to claim 1, characterized in that: The flight controller on board the rocket is equipped with a hardware floating-point unit and integrated DSP instructions, and controls the engine, servo and ducted fan through a 16-channel PWM output interface. The flight controller on the arrow integrates a wireless data link with a transmission power of 1W, a maximum baud rate of 115200bps, and a range of 60km. It is directly connected to the servo control line to realize remote control of the aircraft through the aircraft model remote controller. The onboard flight controller is integrated with a 4GB TF card memory, which stores data at a rate of 512Bytes / 10ms and can save more than 12 hours of flight data for easy post-flight analysis and diagnosis. The Arrow-borne flight controller is equipped with an integrated GPS board.

8. The low-cost rocket-like recoverable test aircraft according to claim 1, characterized in that: The aircraft inertial group adopts a fiber optic gyro strapdown inertial group to measure the angular velocity and linear acceleration of the carrier's motion, and compensate for temperature, installation misalignment angle, nonlinearity, and zero position errors.

9. The low-cost rocket-like recoverable test aircraft according to claim 1, characterized in that: An emergency recovery parachute is arranged in the top fairing of the aircraft as an emergency recovery device to ensure a smooth landing of the aircraft in case of an emergency. The deployment area of ​​the emergency recovery parachute is 12m 2 In a stable state, the aircraft's landing speed is 6-7m / s; a parachute buzzer alarm device is installed on the lower surface of the bottom of the parachute cabin. When the parachute is opened in the air, a 100-120dB alarm sound is emitted to warn ground personnel to stay away.

10. The low-cost rocket-like recoverable test aircraft according to claim 1, characterized in that: The onboard flight controller achieves aircraft control through the following methods: (1) After receiving the ignition command from the ground, the attitude control network parameters are initialized and the initial position parameters are calculated based on the measured inertial group and GPS information; (2) Until the takeoff command from the ground is received, the initial increment calculation of the aircraft inertia group and the initial attitude calculation of the rocket body are continuously performed to determine the initial attitude before takeoff; (3) After receiving the takeoff command from the ground, the aircraft performs the inertial group output increment calculation, strapdown system solution, inertial group information navigation calculation and integrated navigation calculation in sequence according to the inertial group information and GPS information to complete the navigation process of a single control cycle and determine the current position, speed, attitude and attitude angular velocity of the aircraft; (4) Perform guidance calculations based on the mission trajectory and the current aircraft state. If the aircraft position error is greater than a threshold, switch to fault-tolerant guidance law calculations. Otherwise, continue to use the test guidance law to obtain the aircraft thrust command and program angle command. (5) Controlling the aircraft attitude according to the aircraft program angle, performing program angle filtering, attitude deviation calculation, attitude control system parameter calculation, attitude control equation solution, rudder output command and fan output command decomposition and limiting in sequence; (6) Outputting PWM commands of aircraft thrust to the engine, aircraft pitch and yaw commands to two servos, and flight fan control commands to four ducted fans to achieve flight control of the aircraft; (7) If the flight mission is completed, go to (8); otherwise, when the next control cycle begins, go to (3); (8) End the flight and shut down the engine.

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