design of meteorological element detection platform for...

Research ArticleDesign of Meteorological Element Detection Platform forAtmospheric Boundary Layer Based on UAV

Yonghong Zhang,1 Tiantian Dong,1 and Yunping Liu1,2

1B-DAT, C-MEIC, CICAEET, School of Information and Control, Nanjing University of Information Science & Technology,Nanjing, China2Department of Mechanical and Industrial Engineering, Ryerson University, Toronto, ON, Canada

Correspondence should be addressed to Yunping Liu; [email protected]

Received 26 May 2017; Accepted 16 September 2017; Published 2 November 2017

Academic Editor: Hikmat Asadov

Copyright © 2017 Yonghong Zhang et al. This is an open access article distributed under the Creative Commons AttributionLicense, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work isproperly cited.

Among current detection methods of the atmospheric boundary layer, sounding balloon has disadvantages such as low recoveryand low reuse rate, anemometer tower has disadvantages such as fixed location and high cost, and remote sensing detection hasdisadvantages such as low data accuracy. In this paper, a meteorological element sensor was carried on a six-rotor UAVplatform to achieve detection of meteorological elements of the atmospheric boundary layer, and the influence of differentinstallation positions of the meteorological element sensor on the detection accuracy of the meteorological element sensor wasanalyzed through many experiments. Firstly, a six-rotor UAV platform was built through mechanical structure design andcontrol system design. Secondly, data such as temperature, relative humidity, pressure, elevation, and latitude and longitudewere collected by designing a meteorological element detection system. Thirdly, data management of the collected data wasconducted, including local storage and real-time display on ground host computer. Finally, combined with the comprehensiveanalysis of the data of automatic weather station, the validity of the data was verified. This six-rotor UAV platform carrying ameteorological element sensor can effectively realize the direct measurement of the atmospheric boundary layer and in somecases can make up for the deficiency of sounding balloon, anemometer tower, and remote sensing detection.

1. Introduction

The current detection methods of the atmospheric boundarylayer include sounding balloon, anemometer tower, radardetection, and so on [1, 2]. Among which, conventionalsounding balloon and captive balloon have some limitationsin the detection of the atmospheric boundary layer due todisadvantages such as low recovery and low reuse rate. Theobservational approaches of radar detection and remotesensing detection can only obtain relatively low accuracyand reliability of data [3]. Anemometer tower has difficultyin giving consideration to the purpose of research on theatmospheric boundary layer due to disadvantages such asfixed location and high cost. Above all, to seek a high stabilityand low cost, continuously used detection instrument for theatmospheric boundary layer is an urgent problem to besolved. By virtue of features such as easy landing, automatic

cruise, constant height, and constant point [4], it is possiblethat a meteorological element sensor is carried on a six-rotor UAV (unmanned aerial vehicles) platform to realizethe direct measurement of atmospheric sounding. Therefore,developing a meteorological element detection platform forthe atmospheric boundary layer based on UAV has importantscientific significance.

Among current detection methods of atmosphericsounding, sounding balloon carrying a radiosonde for directmeasurement is an important means; however, conventionalsounding balloon and captive balloon have low detectionaccuracy of the atmospheric boundary layer due to disadvan-tages such as low recovery and high cost along with low alti-tude airflow and terrain environment, so they cannot meetthe needs of modern meteorological applications. Therefore,by virtue of features such as easy vertical takeoff and landing,high positioning accuracy, and reusability, it is possible that a

HindawiInternational Journal of Aerospace EngineeringVolume 2017, Article ID 1831676, 14 pageshttps://doi.org/10.1155/2017/1831676

https://doi.org/10.1155/2017/1831676

meteorological element sensor is carried on a six-rotor UAVplatform to make up for the deficiency of sounding balloon insome cases. The observational approaches of radar detectionand remote sensing detection obtain meteorological parame-ters through inversion and observation of indirect variables,and it can only obtain relatively low accuracy and reliabilityof data relative to physical measurement; therefore, it ispossible that a meteorological element sensor is carried ona six-rotor UAV platform to realize the direct measurementof atmospheric boundary layer. Anemometer tower is afacility to observe the vertical distribution of meteorologicalelements of the atmospheric boundary layer but has difficultyin giving consideration to the purpose of research on theatmospheric boundary layer due to disadvantages such asfixed location and high cost. Therefore, detecting the atmo-spheric boundary layer with an UAV has advantages of lowcost and good mobility [5–10].

At present, many research achievements have been madein this field: the United States, Australia, France, and Chinahave developed UAVmeteorological remote sensing systems,such as Perseus, Theseus, and Aerosonde. Aerosonde Ltd.is an Australian-based developer and manufacturer ofunmanned aerial vehicles; in 1995, it started to provide prod-ucts and services related to UAV meteorological detectionsystem, taking the leading position in this field. Reuderet al. observed the meteorological elements of the atmo-spheric boundary layer such as temperature, humidity, andpressure by using SUMO, a small fixed-wing UAV, andachieved good results [11]. China has done a lot of work inthis field and has achieved preliminary results. However, per-forming atmospheric sounding with a fixed-wing UAV hasdeviation in the measurement of meteorological data becausethe fixed-wing UAV will shift substantially on windy daysduring uniform straight up. In contrast, a multirotor UAVcan fly straight up and down on windy days and has betterapplicability than a fixed-wing UAV, so it can perform mete-orological detection of atmospheric layer of different height

[12, 13]. The commonly used multirotor UAVs includefour-rotor UAV and six-rotor UAV, among which, thesix-rotor UAV has two additional rotors compared withfour-rotor UAV; thus, it can exhibit better stability whenit experiences strong external disturbance or part of the rotoris disturbed [14]. Therefore, in this paper, firstly, a six-rotorUAV platform was built through mechanical structuredesign and control system design; secondly, data such as tem-perature, relative humidity, pressure, elevation, and latitudeand longitude were collected by designing a meteorologicalelement detection system; thirdly, data management of thecollected data was conducted, including local storage andreal-time display on ground host computer [15]; and finally,combined with the comprehensive analysis of the data ofautomatic weather station, the validity of the data was verified.

2. Design of Overall System Scheme

The overall system included four parts, namely, six-rotorUAV platform design, meteorological element detection sys-tem design, data management and system testing, and dataanalysis and contrast verification, and the relationshipsbetween the parts are shown in Figure 1. Firstly, a six-rotorUAV, as the flight carrier of detection system, carried ameteorological element detection system to achieve detectionof meteorological elements of the atmospheric boundarylayer. Secondly, the collected data were saved in the SD cardand sent to the host computer for real-time display throughthe wireless data transmission module at the same time.Finally, the comprehensive analysis of the data of automaticweather station was conducted, and contrast verification byexperiment was conducted. The parts are described below:

In this paper, combining the design method of six-rotorUAV flight control system with the design method ofmeteorological element detection system, the meteorologicalsounding of atmospheric boundary layer was studied, on thisbasis, combined with the comprehensive analysis of the data

Six rotorUAV platform

Meteorological elementdetection system

Datamanagement

Data analysiscontrast veri�cation

Datapreservation

Hostcomputer

Data display

IIC

GPIO

SPI

Motor

AttitudeSensor

OLED

USART1

TIM2

Groundstation

Telecontroller

Pressuresensor

Temperaturesensor

GPSSensor

USART1

USART2

IICSD Card

DOUT

Automaticweatherstation

Humidity

Pressure

Temperature

Comparativeanalysis

SD Card

Humiditysensor DOUT

Mas

ter n

glec

hip

Slav

e ngl

echi

p

Figure 1: System diagram.

2 International Journal of Aerospace Engineering

of automatic weather station; the research methods and keytechnologies involved in the parts are as follows:

(1) Six-rotor UAV technology mainly adopted mechani-cal structure design, Mahony complementary filteralgorithm design [16], and hardware and softwaredesign.

The aerodynamic layout of six-rotor UAV had a greatinfluence on the control characteristics and flight quality.Therefore, firstly, the mechanical structure design wasconducted using Solid Works software. Secondly, the mastercontrol conducted programming of flight control systemsoftware using STM32 series chips under MDK (Microcon-troller Development kit) development environment throughMahony complementary filter algorithm design and otherdesigns, and the design of the main program completed theoverall function by means of interrupt nesting. Finally, thehardware circuit and PCB (printed circuit board) layout weredesigned using Altium Designer software, including boardprocessing, welding and debugging, and model six-rotorUAV building.

(2) Meteorological element detection system technologyincluded hardware design, program design, hostcomputer design, and data management.

The master control of the meteorological elementdetection system collected the data of temperature andhumidity sensor, pressure sensor, and GPS sensor usingSTM32 series chips, among which, the hardware design andsoftware program design were conducted using AltiumDesigner software under KEIL environment. As for datamanagement, the meteorological data were displayed bydesigning the host computer software using Visual Basicand saved in the SD card in the form of file system.

(3) As for data analysis and experimental comparison,the system test and contrast test were conducted inthe simulation environment, and the influence ofdifferent installation positions of the meteorologicalelement detection system on the data was analyzed.

In this experiment, under the standard environmentsimulated by a split-type precision humidity generator,firstly, the temperature and humidity of the meteorologicalelement detection system board were tested and analyzedunder different conditions. Secondly, in light of the influenceof the rotor wind of six-rotor UAV on the detection accuracyof the meteorological element sensor during the detection ofatmospheric boundary layer, the influence of different instal-lation positions of the meteorological element sensor on thedetection accuracy of the meteorological element sensorwas analyzed through many experiments. Finally, in the sim-ulation environment, the temperature and humidity of themeteorological element detection system board and DAVISweather station collection board were tested; in the actualtest, the meteorological elements such as temperature, rela-tive humidity, pressure, elevation, and latitude and longitudewere detected by a six-rotor UAV platform carrying a

meteorological element sensor and DAVIS weather stationcollection board, and the validity of the data was verifiedthrough many experiments.

3. Design of Six-Rotor UAV Platform

In light of the influence of meteorological element detectionsystem carried on a six-rotor UAV and other loads on thestability of six-rotor UAV, on the basis of open-sourceplatform, a six-rotor UAV platform of high reliability wasbuilt through the optimization of mechanical structuredesign. The main research contents included the design ofsix-rotor UAV mechanical structure, design of controlsystem hardware, software design, and design of the hostcomputer of the ground station.

3.1. Design of Six-Rotor UAV Mechanical Structure. Thedesign of six-rotor UAVmechanical structure included aero-dynamic layout design and material selection. The six-rotorUAV was a fully actuated system with six outputs and sixfreedoms of motion. The aerodynamic layout design wasthe premise for good flight performance of six-rotor UAV;therefore, the aerodynamic layout of the six-rotor UAVdesigned in this paper chose X6 structure. The aerodynamiclayout and assembly of six-rotor UAV platform are shownin Figures 2 and 3.

The design of six-rotor UAV platform required theassembly of multiple parts, such as center plate of six-rotor

5 2

6 1

4 3

Front

Figure 2: Aerodynamic layout diagram.

Figure 3: Six-rotor UAV platform assembly drawing.

3International Journal of Aerospace Engineering

UAV frame, shaft arm, flight control placing board, screw,and nut, as shown in the following figure. The length of thewheelbase was 650 cm, the shaft arm was designed as a squareof 15 cm× 15 cm, and the center plate of six-rotor UAVframe and shaft arm were fixed with screws and nuts.Through the assembly of multiple parts, a six-rotor UAVplatform was built; on this basis, brushless motor, ESC(electronic speed control), and propeller were assembled,and the X6 structure of six-rotor UAV had better reliabilitythan other structures.

3.2. Design of Flight Control Circuit. The correct design ofhardware circuit was the premise for stable flight of six-rotorUAV. With modular design method being adopted, ameteorological element detection system was carried on thesix-rotor UAV flight control system studied in this paper toperform atmospheric sounding on the premise of ensuringreliable flight of six-rotor UAV. The six-rotor UAV systemstructure is shown in Figure 4.

The six-rotor UAV flight control system circuit includedmain controller circuit, filter circuit, reset circuit, crystal

Telecontroller

Attitudecontrol command

Receiver machine

Data processing

PID controller(1) Gyroscope(2) Accelerometer(3) Magnetometer

ESC 1

Motor 1

ESC 2

Motor 2

ESC 3

Motor 3

ESC 4

Motor 4

ESC 5

Motor 5

ESC 6

Motor 6

Figure 4: Six-rotor UAV system structure diagram.

GND

VCC

PB6

PB7

PB8

PB9

123

456

PWM1

123

456

PWM2

123

456

PWM3

PA6

PA7

PD0 PD1D0

1K

R15 VCC D1

1K

R16 VCCPD2

D2

1K

R17 VCC

VBAT6PC13/TAMPER-RTC7

PC14/OSC32_IN8

PC15/OSC32_OUT9VSS_510VDD_511OSC_IN12OSC_OUT13NRST14

VSSA19VREF-20VREF+21VDDA22PA0/WKUP/USART2_CTS/ADC123_IN0/TIM2_CH1_ETR/TIM5_CH1/TIM8_ETR23PA1/USART2_RTS/ADC123_IN1/TIM5_CH2/TIM2_CH224

PA2/USART2_TX/TIM5_CH3/ADC123_IN2/TIM2_CH225

PA3/USART2_RX/TIM5_CH4/ADC123_IN3/TIM2_CH426VSS_427

VDD_428

PA4/SPI1_NSS/USART_CK/DAC_OUT1/ADC12_IN429PA5/SPI1_SCK/DAC_OUT2/ADC12_IN530PA6/SPI1_MISO/TIM8_BKIN/ADC12_IN6/TIM3_CH1/TIM1_BKIN31

PA7/SPI1_MOSI/TIM8_CH1N/ADC12_IN7/TIM3_CH2/TIM1_CH1N32PB0/ADC12_IN8/TIM3_CH3/TIM8_CH2N/TIM1_CH2N35PB1/ADC12_IN9/TIM3_CH4/TIM8_CH3N/TIM1CH3N36

PB2/BOOT137PB10/I2C2_SCL/USART3_TX/TIM2_CH347PB11/I2C2_SDA/USART3_RX/TIM2_CH448

VSS_149VDD_150 PB12/SPI2_NSS/I2S2_WS/I2C2_SMBA/USART3_CK/TIMBKIN 51PB13/SPI2_SCK/I2S2_CK/USART3_CTS/TIM1_CH1N 52PB14/SPI2_MISO/TIM1_CH2N/USART3_RTS 53PB15/SPI2_MOSI/I2S2_SD/TIM1_CH3N 54

PA9/USART1_TX/TIM1_CH2 68PA10/USART1_RX/TIM1_CH3 69VSS_2 74VDD_2 75PA14/JTCK/SWCLK 76

PD0/OCS_IN/FSMC_D2/CAN_RX 81PD1/OSC_OUT/FSMC_D3/CAN_TX 82PD2/TIM3_ETR/USART5_TX/SDIO_CMD 83

PB6/I2C1_SCL/TIM4_CH1/USART1_TX 92PB7/I2C1_SDA(7)/FSMC_NADV/USART1_RX 93

BOOT0 94PB8/TIM4_CH3(7)/SDIO_D4/I2C1_SCL/CAN_RX 95PB9/TIM4_CH4/SDIO_D5/I2C1_SDA/CAN_TX 96

PE0/TIM4_ETR/FSMC_NBL0 97PE1/FSMC_NBL1 98

VSS_3 99VDD_3 100

STM32F103VCT6

U1

STM32F103VET6

GND

PB6PB7

PB8PB9

BOOT0

3.3V

PD0PD1PD2

GND3.3V

PA9PA10

PB12PB13PB14PB15

GND

VBAT

3.3V X1X2

RESET

PC14PC15

PA0PA1PA2PA3

PA6PA7

GND

0 R10

0 R11

GND

3.3V3.3VA

3.3V

PB0PB1PB2

PB10

3.3V

GND

PB11

GND

3.3VD3

LED1330

R19

10K

R123.3V

RESE

T GND

104C9

1 2SW1

GND

VCCVCC

GND

PA9PA10

PB10PB11

GND

VCCPB15

PB14

PB13PB12

PA0

PA1

PA2

PA3

PA6

PA7

PB0

PB1

1 2 3 4 5 6

OLED

1 2 3 4

TX-RX

1 2 3 4 5

GY-86

1 2 3 4 5 6 7 8CH1-8

X1327681MR13PC14

PC15

X1

X2

GND

10RR143.3V 3.3VA104

C1410ufC7

22

C13

22

C11

22

C10

22

C12X2

8M

C1 C2 C3104104104104C4

104C5

3.3V

GND

GND

1

OUT2 IN 3

AMS11173.3V

GND 104C1710uF

C16 104C15

VCC

Vcc1

Gnd2

Gnd 8

5V 7PWM 6A

3

C5

B4

Power Motor

U4

12

power

14.1V

GNDGND

Figure 5: Flight control system circuit.


oscillator circuit, power interface circuit, serial port circuit,GY-86 attitude sensor circuit, OLED display interface circuit,remote control interface circuit, motor output circuit, andstatus indicator circuit. The normal operation of each mod-ule circuit was the premise for stable flight of six-rotorUAV. The six-rotor UAV system circuit and PCB wiringare shown in Figures 5 and 6.

By adopting the above circuit design, the PCB circuitwas designed using Altium Designer10 software, and theflight control board was designed as a square. The maincontrol chip and attitude sensor were located at the centerof the flight control board; thus, the six-rotor UAV hadeasy access to real attitude information, and the coordinateaxis of attitude sensor was coincident with that of six-rotorUAV frame.

3.3. Software Design. Based on the above design, the mastercontrol conducted programming of UAV flight controlsystem software using STM32 series chips under MDKdevelopment environment, and the design of the main pro-gram completed the overall function by means of interruptnesting. The core of the program was that three interruptions(200Hz, 50Hz, and 10Hz) were set up by timers in the maincycle, namely, scanning the remote control command once,updating the attitude sensor data once, and updating themotor control once to realize control.

After initialization of flight control system, first, theoriginal data of remote control were obtained, and thethrottle was added to data processing to obtain the desiredattitude angle. Meanwhile, the real-time attitude angle ofUAV was obtained using attitude solution algorithm forthree axis acceleration and angular velocity acquired bythe attitude sensor; then, the desired attitude angle andreal-time attitude angle were input into a PID controllerfor operation to obtain the PID outputs of the three attitudeangles. The control flow of control motor after ESC was inputis shown in Figure 7.

The flight control system designed in this paperobtained accurate attitude information through the atti-tude calculation of six-rotor UAV software using Mahony

complementary filter algorithm. The attitude calculation isshown in Figure 8.

First, low-pass filtering and normalization of accelerationoutput by MUP6050 gyroscope were conducted to obtain theunit acceleration. Second, four elements ranging from geo-graphic coordinate system to body coordinate system wereconverted into direction cosine matrix; then, vector productoperation between gravity vector (ax,ay,az) measured bythe accelerometer on the body coordinate system and gravityvector (vx,vy,vz) calculated before was conducted to obtainthe attitude error (ex,ey,ez) between the two, which was usedas the PI-modified gyro bias to obtain the modified angular

Figure 6: PCB wiring diagram.

Remote datainput capture

Remoteoriginal data

Dataprocessing

Desired attitude angle

Attitude sensor

Accelerationangular velocity

Attitudealgorithm

Real-time attitude

Three axis angle separate PID operation

Throttlevolume

Pitch-PID-out Roll-PID-out Yaw-PID-out

Figure 7: Flight control system flow chart.

n system g conversionto b system value(vx,vy,vz)

Vector productoperation

Attitude error(ex,ey,ez)

(ax,ay,az)

Corrected angularvelocity (gx,gy,gz)

Input quaterniondifferential equation

Outputupdate quaternion

Quaterniontransform euler angle

Start

End

First-orderRunge-Kutta method

Quaternionnormalization

Figure 8: Attitude calculation.


velocity (gx,gy,gz). Finally, the quaternion differentialequation was solved using the first-order Runge-Kuttamethod to obtain the quaternion and then the quaternionwas converted into Euler angle.

In this paper, the attitude control algorithm adopted adouble closed loop PID attitude controller, as shown inFigure 9. The main function of this part mainly read attitudesensor data for solution and control. This design adopted thesoft solution posture, and the data read were AD (analog todigital conversion) values of accelerometer and gyroscope;after calibration, filtering, and correction of the data, thethree axis Euler angle was obtained by fusing the four ele-ments. However, the data acquired by the acceleration sensorwere susceptible to distortion, resulting in wrong attitudeangle through attitude calculation. It was difficult for thesystem to operate stably when only using a single loop, sothe angular velocity was added as the inner loop, which wasoutput through data acquisition by the gyroscope. The dataacquired by the gyroscope were generally free from externalinfluence, with strong anti-interference ability; in addition,the angular velocity was sensitive to variation, and its rapidrecovery from external disturbance enhanced the robustnessof the system.

The six-rotor UAV was a three-dimensional coordinate(x,y,z) in the air, and it had requirements for two dimensionsto stay in the air. The first dimension was horizontal direc-tion (x,y,0) in which the six-rotor UAV cannot move backand forth or left and right, and the second dimension wasvertical direction (0,0,z) in which the six-rotor UAV cannotrun out of altitude. There were different technical solutionsto these two dimensions. In the horizontal direction, to deter-mine the position of the six-rotor UAV, GPS positioning wasgenerally used; in the vertical direction, height was deter-mined using a pressure gauge. The six-rotor UAV requiredself-stability and absolute coordinates in the air to achievepositioning, and the barometer adopted in this paper wasMS5611, a high precision barometer, which can achievez-axis positioning in the air. On the z-axis, firstly, the

pressure collected by the pressure sensor was calculatedand corrected; secondly, the accurate pressure was obtainedthrough second-order temperature compensation; andfinally, the absolute height of relative takeoff point wasobtained using the transformation formula. Because theaccuracy of pressure sensor MS5611 was 10 cm, it was neces-sary to fuse the accelerometer complementary filter to obtainthe appropriate height, z-axis speed, and acceleration. In thisdesign, a height double-loop PID controller was formed withheight as the outer ring and speed as the inner ring, and thealtitude hold of z-axis was achieved by adjusting the outputthrottle. The position controller is shown in Figure 10.

4. Design of Meteorological ElementDetection System

At present, the basic meteorological elements in the detec-tion of atmospheric boundary layer included temperature,humidity, pressure, wind speed, wind direction, and pre-cipitation. The precipitation was generally measured usinga rain measuring glass and measuring cup, which was astatic measurement, while the measurement of wind speedand wind direction was greatly influenced by the rotor windof six-rotor UAV. Therefore, in this paper, a meteorologicalelement detection system was designed based on the actualdemand of meteorological detection, and the three elements(temperature, humidity, and pressure) as well as elevationand latitude and longitude were measured. The system struc-ture is shown in Figure 11.

4.1. Circuit Design. The hardware circuit was the basis of theoverall detection platform, and its design needed to considermany aspects, including working environment and selectionof component models, and only the reasonable design of theoverall hardware circuit can complete the work of hardwaresystem of this detection platform. With modular circuitdesign method being adopted, the circuits were connectedthrough Place Net Label, and the circuits as a whole were

Angle PIDcontrol

Desiredeuler angle

Angular velocityPID control

Angular velocityvariation

Attitudeanalysis

Angular velocity/gyroscope

Actualeuler angle

+ +

− −

Figure 9: Attitude controller.

Desiredaltitude

Height PIDcontrol

z-axis speedPID control

Throttlecontrol output

Accelerometercollection

Barometerheight acquisition

Fusion outputz-axis speed

Fusion outputactual height

+ +

− −

Figure 10: Position controller.


simple, intuitive, and readable, as shown in Figure 12. Thecircuit board of the meteorological element detection systemdesigned the position of the meteorological element sensor toensure a secure position of the meteorological elementsensor, and the square design in the bottommost corner ofPCB circuit board was mainly the reserved slot position ofmemory card, as shown in Figure 13.

The meteorological element detection system circuitsincluded controller circuit, reset circuit, crystal oscillationcircuit, BOOT setting circuit, power supply circuit, AM2320circuit, BMP180 circuit, GPS interface circuit, SD cardstorage circuit, and USB serial port conversion circuit.Among which, the USB serial port conversion circuit hadmultiplex functions, which can be used for program flashport or wireless data transmission module interface.

4.2. Program Design. The meteorological element detectionsystem circuits included temperature and humidity collec-tion, pressure acquisition, and geographic coordinate acqui-sition. The communication mode of the meteorologicalelement detection sensor was as follows: temperature andhumidity were transmitted through single bus, pressure wastransmitted through I2C, and elevation, latitude andlongitude, and Beijing time were transmitted through serialport. The program design included pin configuration, com-munication interface initialization, data format conversion,data processing, and data storage. The program flow is shownin Figure 14.

The temperature and humidity were acquired with aAM2320 sensor. In the communication process, the databus was pulled down 18ms from the controller, and

1 23 45 6

BOOT1

Header3X2GND

3.3V

10K

R2

10K

R1BOOT0

10K

R33.3V

X332.768GND

GND

104

C6

20

C12

20

C10

10

10

C14

C15

X18M

1 2SW1

GND

PE14

1 2 3 4

P3 BMP180

GND

VCC PB9PB8

1 2 3 4 5

P4 GPS

VCC

GND

PA2

PA3

10KR1010KR910KR8

3.3V

10KR6

10KR5

GND

PC10PC11

PC12PD

2

PC8PC9

5.1KR7

DAT

A2

1CM

/DAT

A3

2

CMD

3

VD

D4

CLK

5

VSS

6

DAT

A0

7D

ATA

18

99

1010

1111

1212

1313

1414

1515

TF1 TF_CARD

GND

VDD 1DATA 2

NC/GND 3GND 4

U4

3.3V

GND

OSC_IN

OSC_OUT

OSC32_IN

OSC32_OUT

NRS

T

BOOT1 GND 1

TXD2RXD3

V3 4

UD+ 5UD- 6

XI7

XO8

CTS#9DSR#10RI#11DCD#12DTR#13RTS#14R23215

VCC 16

U2

CH340G

VBUS 1D- 2D+ 3ID 4

GND 5U3

USB-AB

GND

VCC

VCC

GND

104

C9

C8

10UFC7

TXDRXD

X2

22

C11

22

C13

GND

104C20

GNDVCC

123

456

POWER_2

12

POWER_1

Header 2GND

3.3V

GN

D1

OUT2 IN 3

U5

3.3V

GND

104C18 104

C16

VCC

47uf

+C17

47uf/25V

+

C19

3.3V

VBAT6PC13/TAMPER-RTC7PC14/OSC32_IN8

PC15/OSC32_OUT9VSS_510VDD_511

OSC_IN12OSC_OUT13NRST14

VSSA19VREF-20

VREF+21

VDDA22PA0/WKUP/USART2_CTS/ADC123_IN0/TIM2_CH1_ETR23

PA1/USART2_RTS/ADC123_IN1/TIM5_CH2/TIM2_CH224

PA2/USART2_TX/TIM5_CH3/ADC123_IN2/TIM2_CH225PA3/USART2_RX/TIM5_CH4/ADC123_IN3/TIM2_CH426

VSS_427

VDD_428

PA6/SPI1_MISO/TIM8_BKIN/ADC12_IN6/TIM3_CH1/TIM1_BKIN31

PA7/SPI1_MOSI/TIM8_CH1N/ADC12_IN7/TIM3_CH2/TIM1_CH1N32

PB0/ADC12_IN8/TIM3_CH3/TIM8_CH2N35

PB1/ADC12_IN9/TIM3_CH4/TIM8_CH3N36PB2/BOOT137

PE14/FSMC_D11/TIM1_CH445PB10/I2C2_SCL/USART3_TX/TIM2_CH347PB11/I2C2_SDA/USART3_RX/TIM2_CH448 VSS_1 49VDD_1 50PC8/TIM8_CH3/SDIO_D0/TIM3_CH3 65PC9/TIM8_CH4/SDIO_D1/TIM3_CH4 66

PA9/USART1_TX/TIM1_CH2 68PA10/USART1_RX/TIM1_CH3 69VSS_2 74VDD_2 75

PC10/USART4_TX/SDIO_D2/USART3_TX 78PC11/USART4_RX/SDIO_D3/USART3_RX 79PC12/USART5_TX/SDIO_CK/USART_CK 80

PD0/OCS_IN/FSMC_D2/CAN_RX 81PD1/OSC_OUT/FSMC_D3/CAN_TX 82PD2/TIM3_ETR/USART5_TX/SDIO_CMD 83PB6/I2C1_SCL/TIM4_CH1/USART1_TX 92PB7/I2C1_SDA(7)/FSMC_NADV/USART1_RX 93BOOT0 94PB8/TIM4_CH3(7)/SDIO_D4/I2C1_SCL/CAN_RX 95PB9/TIM4_CH4/SDIO_D5/I2C1_SDA/CAN_TX 96PE0/TIM4_ETR/FSMC_NBL0 97PE1/FSMC_NBL1 98VSS_3 99VDD_3 100

STM32F103VCT6

U1

STM32F103VET6

104C1

104C2

104C3

104C4

104C5

3.3V

GND

GND3.3VD1 LED1

330

R4

PB6PB7

PB8PB9

BOOT0

3.3V

PD0PD1PD2

PC12PC11PC10

GND3.3V

PA9PA10

PC8PC9

GND3.3V

1 2

P1 VBAT

3.3V

OSC_INOSC_OUTNRST

OSC32_INOSC32_OUT

GND

PA0PA1PA2PA3

GND

3.3V

3.3VPA6PA7

PB0PB1BOOT1

PB10PB11

PE14

GND

3.3V

104

+

Figure 12: Detection system circuit.

Localstorage (SD)

PC display

Dataprocessing

Sensordata

acquisition

Temperature andHumidity sensor

Pressuresensor

GPS sensor

Datadetection

Slavecontroller

Datamanagement

Figure 11: Meteorological element detection system structure diagram.


AM2320 sensor was converted from sleep mode to high-speed mode and sent response signal after waiting the startsignal from the controller to end; it sent 40-bit data fromthe data bus, after which the information acquisition wastriggered once, and after the information collection ended,AM2320 sensor automatically entered sleep mode to wait

for the next communication. The communication process isshown in Figure 15(a).

The pressure was acquired with a BMP180 pressure sen-sor and communicated via I2C. When the BMP180 pressuresensor started working, it read the data of pressure sensorfrom the I2C interface of the controller, then conducted

1 2

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12345678910

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DHT11

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R7

R6 R5 R9 R8R10

C20

TF1 TF1

TF_CARD

BMP180

P3

P4

GPS

STM32F103VET6CH34

0G

BOOT1

BOO

T1

BOO

T0

R2

R1

U5

C18 LM1 117 C16

C17

C19

65

G

G

POWER_1

POWER_2

PA10 PA9

3.3

3.33114

12 24

P2

X2G 6 3 +

C13

C11

USB-A

U3

C10

U2 U1

C12

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C6 R3

Res

SW1

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X1R4

D1

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C15C14

P1

X3

VBAT

C5

11

1615

1413

1211

109

87

65

43

21

Figure 13: PCB wiring diagram.


temperature compensation for such data, and finally obtainedhigh accuracy pressure. The communication process is shownin Figure 15(b).

As for geographic coordinate acquisition, the elevation,latitude, and longitude were acquired with a NEO-6M GPSsensor and then decoded through a NMEA base. The datawere communicated from serial port 2 (USART2) ofSTM32F103VET6 controller through serial port and sent tomemory from peripheral (serial port 2) of STM32F103VET6controller through direct memory access (DMA). The com-munication process is shown in Figure 15(c).

In this paper, a meteorological element detection systemwas designed, and the three elements (temperature, humid-ity, and pressure) and elevation, latitude, and longitude werecollected and saved in the SD card from the controller.Meanwhile, the data were sent to the host computer of themeteorological element detection system through the wire-less data transmission module for real-time display.

4.3. Design of Host Computer Software. The core task of thehost computer software of the meteorological elementdetection system designed in this paper was to display,process, and store data, as shown in Figure 16.

The host computer software communicated with themeteorological element detection system through the wire-less data transmission module, which was convenient forthe data transmission of meteorological elements. In additionto the operating system, there was no need to configure othersoftware environment. This host computer was written usingVisual Basic, and the interfaces included serial port parame-ter setting, real-time data display, time data, historical data

query, and various function keys, which can realize thefunction of receiving and displaying meteorological elements.

The data of the host computer software and meteorolog-ical element detection system were transmitted through serialport; in the connection mode, the transmitting terminal ofwireless data transmission module was connected with themeteorological element detection system, and the receivingterminal was connected with the ground PC terminal (com-puter), and the data were sent to the host computer forreal-time display from the meteorological element detectionsystem through the serial port communication between wire-less data transmission modules. The meteorological elementdetection system conducted design of communication proto-cols for the transmitted data, including frame header, datalength, data block, check, and frame tail, so as to ensure theintegrity of the data. The protocol rules are shown in Table 1.

5. Building of Complete Six-Rotor UAV

The building of model six-rotor UAV was the premise fornormal operation, and function requirements can be realizedthrough welding, debugging, final checking function, andvarious indicators of the complete six-rotor UAV. The flightcontrol board of six-rotor UAV is shown in Figure 17(a), andthe meteorological element detection board of six-rotor UAVis shown in Figure 17(b).

In this paper, through hardware and software debugging,a meteorological element detection system was carried on asix-rotor UAV platform to achieve collection of meteorolog-ical elements of atmospheric boundary layer, such as temper-ature, relative humidity, pressure, elevation, latitude andlongitude, and current time, and the collected data weresaved in the SD card; meanwhile, the data were sent to thehost computer of the meteorological element detectionsystem through the wireless data transmission module forreal-time display. In the test flight experiment, the six-rotorUAV platform maintained stable flight, and the collectionand storage of meteorological elements by the meteorologicalelement detection system as well as real-time display on thehost computer were realized, as shown in Figure 18.

As can be seen from flight waveform in Figure 19, thesix-rotor UAV platform carrying a meteorological elementdetection system showed small fluctuation of attitude angleduring flight, which was around 0.4°, proving that thesix-rotor UAV flight control platform designed in this paperhad good self-stability effect.

6. Analysis of Experimental Data

To ensure the correctness and validity of data analysis, first,the influence of different installation positions of the meteo-rological element sensor on the data analysis result wasanalyzed, then, the meteorological elements were detectedand the data were analyzed by a six-rotor UAV platformcarrying a meteorological element detection system andDAVIS weather station collection board, and the validity ofthe system was verified.

Data processing(different sampling frequency)

Temperaturehumidity

Atmosphericpressure

AltitudeLatitude

Receive data and format conversion

End

Start

Hardware interfaceinitialization (USART, IIC, SDIO)

Read data fromslave controller

SD card write Host computer display

Longitude

Figure 14: Program design flow chart.


6.1. Test of Position Installation. At present, it has been atrend that a meteorological element sensor is carried on aUAV platform to achieve detection of meteorological ele-ments of the atmospheric boundary layer, which can realizedetection and research of different regions, but the rotorwind of UAV has some influence on the detection accuracy

of the meteorological element sensor. The integrated andcoordinated detection by a UAV-borne multisensor hasbecome the mainstream of the current and future workmodel, which is the future development trend. Therefore, inthis chapter, based on the future integrated detection by aUAV-borne multisensor, different installation positions ofthe UAV-borne multisensor were studied, and the influenceof different installation positions of the meteorological ele-ment sensor on the accuracy of detection data was analyzedthrough many experiments.

According to the survey, the experiment mainly con-ducted an analysis of detection data of three differentinstallation positions of the meteorological element detec-tion system. Through hydrodynamic analysis, the meteo-rological element detection system was installed below,above, and 10 cm above the center plate of six-rotorUAV frame. The test data of this experiment are shownin Figure 20.

The experimental data selected the test data in 10minutes in the experimental test, and analysis of tempera-ture, humidity, and pressure was conducted, respectively.As can be seen from Figure 20, when the meteorologicalelement detection system was installed above and below thecenter plate of six-rotor UAV frame, the temperature andhumidity curves showed large fluctuation, and the pressurecurve showed small fluctuation; when the meteorologicalelement detection system was installed 10 cm above thecenter plate of six-rotor UAV frame, the temperature andhumidity curves showed smooth fluctuation, and thepressure curve showed small fluctuation.

In the experiment, when the meteorological elementdetection system was installed above and below the centerplate of six-rotor UAV frame, the temperature and humiditycurves showed large fluctuation, because of influence of the

Start

Slave controllersend start signal

Wait for startsignal end

Read data(40 bit)

AM2320 sendresponse signal

Data verification

Update temperatureand humidity value

Y

N

End

(a)

Start

Start temperature measurement

Read temperature

Start pressure measurement

Reading pressure

Calibrated pressure

End

(b)

Start

DMA configure

Obtain GPS information

GPS decode

Output latitude and longitude

Output altitude

End

(c)

Figure 15: (a) Temperature and humidity collection. (b) Pressure collection. (c) Elevation, latitude, and longitude collection.

Figure 16: Host computer software.

Table 1: Format frame.

Explain Code Byte

Frame header 0x45, 0xBB, 0x7E 3

Data length 0x02 2

Data block 0x23, 0x45 0~255Check SUM 1

Frame tail 0x0D 1


downward rotor wind of six-rotor UAV as the positionsabove and below the center plate of six-rotor UAV framewere below the propeller; when the meteorological elementdetection system was installed 10 cm above the center plateof six-rotor UAV frame, the temperature and humiditycurves showed smooth fluctuation, because of little influenceof the rotor wind of six-rotor UAV as the position 10 cmabove the center plate of six-rotor UAV frame was abovethe propeller. Therefore, the meteorological element detec-tion system was installed 10 cm above the center plate ofUAV frame.

6.2. Contrast Test. The meteorological elements such as tem-perature, humidity, and pressure were detected by a six-rotorUAV platform carrying a meteorological element sensor andDAVIS weather station collection board, and the experimen-tal data selected two sets of test data in 10 minutes in theexperimental test, as shown in Figure 21.

As can be seen from Figure 21, the temperature andhumidity curves and pressure curve were consistent withthe trend of curve of the data collected by the DAVIS weatherstation, which met the design requirements. As can be seenfrom Figure 21(a), the error between the temperature curve

of the meteorological element detection system and thetemperature curve of the DAVIS weather station was about0.5°C, which was in line with the margin of error of temper-ature accuracy. Figures 21(c) and 21(d) show that the humid-ity curves of the meteorological element detection system andthe DAVIS weather station were basically coincident witheach other. Figures 21(e) and 21(f) show that the pressurecurves of the meteorological element detection system andthe DAVIS weather station showed certain fluctuation andthe overall trends were the same due to the small fluctuation,so the data were valid.

7. Conclusions

In this paper, a meteorological element detection systemwas carried on a six-rotor UAV platform to achieve collec-tion and analysis of meteorological elements of the atmo-spheric boundary layer. The main works were summarizedas follows:

(1) In light of the influence of meteorological elementdetection system carried on a six-rotor UAV andother loads on the stability of six-rotor UAV, the

(a) (b)

Figure 17: (a) Flight control board. (b) Detection board.

(a) (b)

Figure 18: (a) Model six-rotor UAV. (b) Test flight experiment.


200015001000

5000

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78,207 78,307 78,407 78,507 78,607 78,707 78,807 78,907 78,007

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86,405 86,505 86,605 86,705 86,805 86,905 87,005 87,105 87,205

(c) Roll angle

Figure 19: Flight attitude angle. Note: x-axis was time (t/s), and y-axis was angle (°/1000).

89

101112131415161718

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ture

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idity

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%)

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10051007100910111013101510171019102110231025

Pres

sure

(hPa

)

Pressure curve

DownUpRaise 10 cm

Time (min)1 2 3 4 5 6 7 8 9 10

(c)

Figure 20: Test curves.


flight stability of six-rotor UAV was improvedthrough the optimization of attitude controller andposition controller.

(2) In light of the detection requirements of the atmo-spheric boundary layer, a meteorological elementdetection system was designed to achieve detectionand storage of meteorological elements such as tem-perature, relative humidity, pressure, elevation, andlatitude and longitude. In view of the influence ofthe rotor wind on the detection accuracy of the mete-orological element detection sensor, the installation

location is spatially higher than the propeller plane,and the influence of the rotor wind is the smallest.Through a large number of experimental studies, itis found that the installation position is 10 cm abovethe frame, and sensor accuracy can be achieved: tem-perature accuracy: △T≤ 0.5°C; humidity accuracy:△U≤ 6RH%; air pressure accuracy: 0.5 hPa; altitude:3M, to ensure the accuracy of the detection results.It reveals the position relation between unmannedaerial vehicle and meteorological sensor, which is ofgreat significance to guide the system structure design.

Detection system

Time (min)

1 2 3 4 5 6 7 8 9 10

DAVIS

6.57.58.59.5

10.511.512.513.514.5

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(°C)

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Humidity curve8685848382818079787776

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idity

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10301029102810271026102510241023102210211020

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(f)

Figure 21: Test curves.


(3) In light of the meteorological elements collected, thetemperature, humidity, and air pressure were ana-lyzed by automatic weather station data. The temper-ature curve, humidity curve, and air pressure curvewere consistent with the trend of data curve collectedby DAVIS weather station, and the validity of thedesign was clarified.

Conflicts of Interest

The authors declare that there is no conflict of interestsregarding the publication of this paper.

Acknowledgments

This work was supported by project supported by theNational Natural Science Foundation of China (51575283and 51405243).

References

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