1. A real-time thrust test system of a distributed electric propulsion unmanned aerial vehicle is characterized by comprising an electric propeller ground test system and an airborne electric signal real-time acquisition system;

the electric propeller ground test system comprises a test bench, a force measuring device and a programmable power supply; the unmanned aerial vehicle propulsion unit is arranged on the test bench; the programmable power supply outputs according to the external characteristic curve of the propulsion unit to supply power to the propulsion unit; the test bench is arranged on the force measuring device for zeroing calibration, the programmable power supply supplies power to the propulsion unit after the calibration is finished, and the propulsion unit starts to work; recording different thrust data corresponding to different outputs of the programmable power supply, and drawing a thrust-power curve according to the recorded data;

the airborne electric signal real-time acquisition system comprises a core control panel, a power supply system, a voltage conditioning circuit, a current conditioning circuit and a current sensor;

the core control board collects and processes data based on STM 32;

the voltage conditioning circuit adopts a high-precision operational amplifier to attenuate the input voltage to the rated voltage range of the A/D interface of the core control board; voltage signals to be measured of the system enter an acquisition chip of a core control panel through an A/D interface, the core control panel transmits acquired voltage data to an unmanned aerial vehicle data transmission system through an RS232 interface, and the data are returned to a ground station in real time through the unmanned aerial vehicle data transmission system;

the current conditioning circuit converts a current signal of the detected propulsion unit into a voltage signal through the current sensor, and the voltage signal is attenuated to reach the rated voltage range of the A/D interface of the core control board and is input into the core control board; the core control board returns the current signal of the detected propulsion unit to the ground station in real time through the data transmission system;

the power supply system supplies power in a +/-15V mode and a +/-5V mode, the +/-15V mode supplies power to the operational amplifier in the voltage conditioning circuit and the current conditioning circuit, and the +/-5V mode supplies power to the current sensor and the core control panel.

2. The real-time thrust testing system of the distributed electric propulsion unmanned aerial vehicle of claim 1, wherein the power supply system is of a modular design and is conveniently installed in the body of the unmanned aerial vehicle to supply power to the real-time airborne electric signal acquisition system.

3. The real-time thrust testing system of the distributed electric propulsion unmanned aerial vehicle of claim 1, wherein the power supply system is installed in a fuselage and connected to other circuits of the real-time airborne electric signal acquisition system through an anti-reverse plug and a flat cable.

4. The real-time thrust testing system of the distributed electric propulsion unmanned aerial vehicle of claim 1, wherein the voltage conditioning circuit and the current conditioning circuit are installed in the wings of the unmanned aerial vehicle at positions close to the power section so as to accurately acquire current and voltage signals of each propulsion unit.

5. The real-time thrust estimation method of the distributed electric propulsion unmanned aerial vehicle is characterized by comprising the following steps of:

step 1: filtering data acquired by an airborne real-time testing system at a ground station, and filtering out singular points in the acquired data;

step 2: according to the thrust-power curve, performing curve fitting to obtain a functional relation between thrust and power, as shown in formula (1):

T(P)＝a×P²+b×P+c (1)

wherein, P represents power a, power b and power c are fitting coefficients respectively, and T (P) represents thrust;

and step 3: and calculating a real-time electric power value through current and voltage parameters acquired by the airborne electric signal real-time acquisition system in real time, bringing the real-time calculated electric power value into the formula (1), and estimating to obtain thrust data generated by the propulsion unit in real time.

Background

With the rapid development of air traffic, environmental problems brought by air transportation industries such as air freight, urban navigation and the like are urgently to be solved, and people are trying to find a solution for replacing the traditional fossil fuel. The United states and European Union also continuously provide new requirements for the next generation of commercial aircraft in the aspects of fuel consumption, noise control pollutant discharge and the like, and establish development targets. On the basis of the development of multi/full electric aircraft technology, the electric propulsion technology becomes an important development direction for electrification of an aircraft power system, and the electric aircraft is expected to further improve the flight aerodynamic efficiency and fuel economy of an aircraft power system and reduce the emission of noise and pollutants.

Compared with the traditional centralized propulsion mode, after the distributed electric propulsion mode decomposes a centralized single high-power engine or motor system into a plurality of low-power motor distributed propulsion systems with the same total power, the power density and the efficiency of the whole power system are basically unchanged, the bypass ratio of the propulsion system can be effectively improved, the energy management and control of the system are more flexible, the fault tolerance performance is better, the performance of a power device can be effectively improved, and the fuel consumption rate is improved. In addition, each ducted fan of the distributed propulsion system can be more conveniently merged into the aircraft body, so that the aerodynamic efficiency of the aircraft is higher. Considering that the distributed electric propulsion aircraft needs to generate different thrusts through thrusters distributed at different positions of the aircraft body to complete the flight attitude change in the flight process, a real-time testing technology of the thrusters generating the thrusts in the flight process is very important. Currently, the international thrust test methods in the aviation field mainly include the following methods:

the vehicle-mounted test platform test method comprises the following steps: the assembly of the ducted fan, the speed regulator and the like electric propulsion system is installed on a vehicle-mounted mobile test platform, and the mobile vehicle-mounted test platform can simulate the air flow characteristics. Meanwhile, a testing device of the electric propulsion system adopts a high-frequency data acquisition system and a sensor to complete the thrust testing work. Although the method can replace wind tunnel experiments, real-time thrust data in the flight process cannot be obtained.

The thrust test method using the hinge or linear bearing and the strain force sensor comprises the following steps: the propulsion unit is mounted on a first plate and a second plate is mounted on the fuselage. And the two plates are connected with the bottom of the second plate through hinges, and strain force transducers are arranged on the upper edges of the two plates to measure the moment of the hinges so as to measure the thrust generated by the propulsion unit. The method can test the thrust in real time, but the sensing moment of the hinge can cause certain errors of the measurement result. The problem caused by the induced torque can be solved by replacing the hinge with the linear bearing, and the influence of the friction force in the bearing and the linearity and accuracy of the force sensor on the measurement result still exists.

Testing the thrust vectoring force of the spray pipe: the thrust characteristic of the spray pipe is mainly tested and researched in a wind tunnel test, and the purpose of the test is mainly to measure the thrust and the thrust deflection angle of the spray pipe. The technical method research of jet thrust characteristic measurement is carried out by utilizing a nozzle balance embedded in a jet simulator. A special balance calibration frame is designed by adopting an air bridge technology, and a combined thrust correction method of the spray pipe balance is provided by combining an external calibration balance. However, this method is not applicable to a propulsion system in which a ducted fan is used as a propulsion unit.

There is also a guide platform side thrust: the ducted fan is arranged on the test platform, the ducted fan is arranged on the guide structure, the ducted fan can freely move along the guide structure, the force measuring device is arranged at one end of the test platform, the ducted fan and the force measuring device are connected through the connecting piece, and the force measuring device can measure the current thrust when the ducted fan moves. However, such a force-measuring platform cannot measure thrust in real time during actual flight of the aircraft.

Disclosure of Invention

In order to overcome the defects of the prior art, the invention provides a thrust real-time test system and a method of a distributed electric propulsion unmanned aerial vehicle, which comprises an electric propeller ground test system and an airborne electric signal real-time acquisition system; firstly, designing a ground experiment table of an electric propeller ground test system, obtaining a thrust curve through ground test, and obtaining a force-effect function relation of a tested propeller through curve fitting; then designing a real-time acquisition system of the airborne electric signals, and acquiring the electric parameters of each propulsion unit in real time; and finally, designing a real-time thrust estimation method, and estimating real-time thrust generated by each propeller when the unmanned aerial vehicle flies by using the acquired data. The real-time thrust test system and the estimation method have high test precision, and can obtain real-time thrust data of each propulsion unit of the distributed electric propulsion unmanned aerial vehicle in real time at the ground station.

The technical scheme adopted by the invention for solving the technical problems is as follows:

a real-time thrust test system of a distributed electric propulsion unmanned aerial vehicle comprises an electric propeller ground test system and an airborne electric signal real-time acquisition system;

the electric propeller ground test system comprises a test bench, a force measuring device and a programmable power supply; the unmanned aerial vehicle propulsion unit is arranged on the test bench; the programmable power supply outputs according to the external characteristic curve of the propulsion unit to supply power to the propulsion unit; the test bench is arranged on the force measuring device for zeroing calibration, the programmable power supply supplies power to the propulsion unit after the calibration is finished, and the propulsion unit starts to work; recording different thrust data corresponding to different outputs of the programmable power supply, and drawing a thrust-power curve according to the recorded data;

the airborne electric signal real-time acquisition system comprises a core control panel, a power supply system, a voltage conditioning circuit, a current conditioning circuit and a current sensor;

the core control board collects and processes data based on STM 32;

the voltage conditioning circuit adopts a high-precision operational amplifier to attenuate the input voltage to the rated voltage range of the A/D interface of the core control board; voltage signals to be measured of the system enter an acquisition chip of a core control panel through an A/D interface, the core control panel transmits acquired voltage data to an unmanned aerial vehicle data transmission system through an RS232 interface, and the data are returned to a ground station in real time through the unmanned aerial vehicle data transmission system;

the current conditioning circuit converts a current signal of the detected propulsion unit into a voltage signal through the current sensor, and the voltage signal is attenuated to reach the rated voltage range of the A/D interface of the core control board and is input into the core control board; the core control board returns the current signal of the detected propulsion unit to the ground station in real time through the data transmission system;

the power supply system supplies power in a +/-15V mode and a +/-5V mode, the +/-15V mode supplies power to the operational amplifier in the voltage conditioning circuit and the current conditioning circuit, and the +/-5V mode supplies power to the current sensor and the core control panel.

Preferably, electrical power generating system adopts the modularized design, conveniently installs and supplies power for the real-time collection system of airborne signal of telecommunication among the unmanned aerial vehicle fuselage.

Preferably, the power supply system is installed in the fuselage and is connected to other circuits of the airborne electric signal real-time acquisition system through an anti-reverse plug and a flat cable.

Preferably, the voltage conditioning circuit and the current conditioning circuit are installed in the wing of the unmanned aerial vehicle at a position close to the power section so as to accurately acquire current and voltage signals of each propulsion unit.

A real-time thrust estimation method for a distributed electric propulsion unmanned aerial vehicle comprises the following steps:

step 1: filtering data acquired by an airborne real-time testing system at a ground station, and filtering out singular points in the acquired data;

step 2: according to the thrust-power curve, performing curve fitting to obtain a functional relation between thrust and power, as shown in formula (1):

T(P)＝a×P²+b×P+c (1)

wherein, P represents power a, power b and power c are fitting coefficients respectively, and T (P) represents thrust;

and step 3: and calculating a real-time electric power value through current and voltage parameters acquired by the airborne electric signal real-time acquisition system in real time, bringing the real-time calculated electric power value into the formula (1), and estimating to obtain thrust data generated by the propulsion unit in real time.

The invention has the following beneficial effects:

all circuits of the system adopt modular design, have the characteristics of small volume and light weight, and are easy to install at the position of the wing close to the propulsion unit;

the real-time thrust test system and the estimation method have high test precision, and can obtain real-time thrust data of each propulsion unit of the distributed electric propulsion unmanned aerial vehicle in real time at the ground station.

Drawings

FIG. 1 is a flow chart of a real-time thrust test of a propulsion unit according to the present invention.

FIG. 2 is a schematic diagram of the electrical thruster ground test system of the present invention.

FIG. 3 is a schematic view of a test bench for an electric propulsion ground test system according to the present invention.

FIG. 4 is a schematic circuit diagram of the airborne electric signal real-time acquisition system of the present invention.

FIG. 5 is a diagram of an STM32 core PCB according to the present invention.

FIG. 6 is a diagram of a PCB of the current conditioning circuit of the present invention.

FIG. 7 is a diagram of a voltage conditioning circuit PCB of the present invention.

FIG. 8 is a diagram of a power system PCB of the present invention.

FIG. 9 is an installation diagram of the real-time electrical parameter testing system of the airborne propulsion unit of the present invention.

FIG. 10 is a flight deck thrust estimation curve according to an embodiment of the present invention.

Detailed Description

The invention is further illustrated with reference to the following figures and examples.

In order to solve the problems of various testing methods in the prior art, the invention designs the small-size and light-weight airborne real-time electric parameter testing system of the distributed electric propulsion unmanned aerial vehicle, is suitable for electric parameter testing of each propulsion unit of the distributed electric propulsion system, and can be installed on the distributed electric propulsion unmanned aerial vehicle for use. The system takes an stm32 microcontroller chip as a core, adopts a modular design, and is conveniently installed at a position close to a power section in a wing so as to achieve the purpose of accurately acquiring electrical parameter signals such as current and voltage of each propulsion unit.

The thrust generated by each propeller in real time is indirectly estimated by collecting the real-time electric parameter signal data of each propulsion unit, so that a data reference basis is provided for the distributed electric propulsion airplane to realize an attitude control method and a flight control means without a steering engine.

The real-time thrust testing process of the electric propulsion unit is shown in fig. 1, and mainly comprises a ground testing system of the electric propulsion unit, an airborne electric signal real-time acquisition system and a real-time thrust estimation method.

The specific work flow is as follows:

(1) designing a ground experiment table of the ground test system of the electric propeller, obtaining a thrust curve by carrying out ground test, and obtaining a force-effect function relation of the tested propeller by curve fitting;

(2) designing a real-time airborne electric signal acquisition system, and acquiring the electric parameters of each propulsion unit in real time;

(3) and designing a real-time thrust estimation method, and estimating real-time thrust generated by each propeller when the unmanned aerial vehicle flies by using the acquired data.

A real-time thrust test system of a distributed electric propulsion unmanned aerial vehicle comprises an electric propeller ground test system and an airborne electric signal real-time acquisition system;

as shown in fig. 2 and 3, the electric thruster ground test system comprises a test bench, a force measuring device and a programmable power supply; the unmanned aerial vehicle propulsion unit is arranged on the test bench; the programmable power supply outputs according to the external characteristic curve of the propulsion unit to supply power to the propulsion unit; the test bench is arranged on the force measuring device for zeroing calibration, the programmable power supply supplies power to the propulsion unit after the calibration is finished, the propulsion unit starts to work, and the bench can test thrust data generated by different electric powers of the tested propeller; recording different thrust data corresponding to different outputs of the programmable power supply, and drawing a thrust-power curve according to the recorded data;

as shown in fig. 4, the airborne electric signal real-time acquisition system includes a core control board, a power supply system, a voltage conditioning circuit, a current conditioning circuit and a current sensor;

the core control board collects and processes data based on STM 32; aiming at a distributed electric propulsion unmanned aerial vehicle, each power section of a propulsion system is provided with a core board based on STM32 to acquire and process data;

the voltage conditioning circuit adopts a high-precision operational amplifier to attenuate the input voltage to the rated voltage range of the A/D interface of the core control board; voltage signals to be measured of the system enter an acquisition chip of a core control panel through an A/D interface, the core control panel transmits acquired voltage data to an unmanned aerial vehicle data transmission system through an RS232 interface, and the data are returned to a ground station in real time through the unmanned aerial vehicle data transmission system;

the current conditioning circuit converts a current signal of the detected propulsion unit into a voltage signal through the current sensor, and the voltage signal is attenuated to reach the rated voltage range of the A/D interface of the core control board and is input into the core control board; the core control board returns the current signal of the detected propulsion unit to the ground station in real time through the data transmission system;

the power supply system supplies power in a +/-15V mode and a +/-5V mode, the +/-15V mode supplies power to the operational amplifier in the voltage conditioning circuit and the current conditioning circuit, and the +/-5V mode supplies power to the current sensor and the core control panel.

A real-time thrust estimation method for a distributed electric propulsion unmanned aerial vehicle comprises the following steps:

step 1: filtering data acquired by an airborne real-time testing system at a ground station, and filtering out singular points in the acquired data;

step 2: according to the thrust-power curve, performing curve fitting to obtain a functional relation between thrust and power, as shown in formula (1):

T(P)＝a×P²+b×P+c (1)

wherein, P represents power a, power b and power c are fitting coefficients respectively, and T (P) represents thrust;

and step 3: and calculating a real-time electric power value through current and voltage parameters acquired by the airborne electric signal real-time acquisition system in real time, bringing the real-time calculated electric power value into the formula (1), and estimating to obtain thrust data generated by the propulsion unit in real time.

The PCB circuit diagrams of the airborne electric signal real-time acquisition system are respectively shown in figures 5-8. All parts of circuits are in modular design, have the characteristics of small size and light weight, and are easy to install at the positions close to the propulsion units with the wings. The whole real-time thrust test system and the estimation method have high test precision, and real-time thrust data of each propulsion unit of the distributed electric propulsion unmanned aerial vehicle can be obtained in real time at a ground station.

The specific embodiment is as follows:

the designed real-time test system for the electrical parameters of the airborne propulsion unit is installed on a distributed electric propulsion unmanned aerial vehicle with 24 ducted fans providing thrust, and the installation mode is shown in fig. 9; testing and collecting real-time electrical parameter data of the unmanned aerial vehicle during one-flight-frame flight, and estimating real-time thrust by the collected data, wherein an estimated thrust curve is shown in fig. 10; the estimated thrust error is small, and the estimation method and the design of a hardware system achieve the expected effect.