Share 2018 Electronics Competition Paper - [B- Fire Extinguishing Aircraft] Fujian Province Ti Cup Special Prize / Xiamen University / Changmen University Team

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Share 2018 Electronics Competition Paper - [B- Fire Extinguishing Aircraft] Fujian Province Ti Cup Special Prize / Xiamen University / Changmen University Team [Copy link]

Summary

The quadcopter is a small-sized, relatively simple-to-control aircraft. The quadcopter designed in this project uses only a TI MSP-EXP432P401R microcontroller as the main control chip, which is also the feature of this group. The main control chip reads the quadcopter Euler angle data collected from the nine-axis accelerometer gyroscope ICM20600 for PID processing to keep the aircraft's attitude stable; the SPL06 air pressure sensor and the ultrasonic ranging module US-100 are used to control the altitude of the quadcopter flight; and the Openmv high-definition video is used to track the fire extinguishing position of the red LED light. This quadcopter can realize autonomous takeoff and hovering, fixed-altitude flight cruise, search for light source fire extinguishing, directional crossing, and fixed-point landing. After testing, the aircraft in this group has excellent performance and exquisite design, which meets the requirements of this project.

Keywords: quadrotor; Texas Instruments MSP-EXP432P401R; ICM20600 nine-axis accelerometer and gyroscope; PID control; US-100 ultrasonic ranging; target tracking

1. System Solution

1 Demonstration and selection of main control module

Solution 1: Use Texas Instruments MSP-EXP432P401 microcontroller as the core and design the flight control board independently. However, there are few open sources online and the compilation environment is unfamiliar, so it is difficult to design the flight control board independently.
Solution 2: Use the finished flight control and control it with Texas Instruments MSP-EXP432P401 to save time. However, we need to add some sensor modules such as cameras and ultrasonic waves.
After considering the advantages and disadvantages of the above two solutions, we adopted Solution 2.

2. Selection and demonstration of flight attitude control

Solution 1: Cross flight mode. The four motors of the quadcopter are arranged in a cross pattern, with the x-axis and y-axis at right angles. The pitch angle and roll angle are adjusted separately. The angle fusion is simple and suitable for beginners. The head and tail can be clearly identified, the body movements are accurate during flight, and the flight control is also easy. However, there are relatively few finished flight controllers of this type on the Internet.

Option 2: X-shaped flight mode. The four motors of the quadcopter are arranged in an X-shaped pattern, which is highly flexible and adjustable. When adjusting, the two adjacent motors should be adjusted in a fusion manner, which is complex. The X-shaped flight mode is very free and flexible, with various rotation methods. It can fly in various ways and perform many difficult actions, but it is relatively difficult to control. However, there are mature finished flight control products, which are more advantageous for autonomous flight.
Combining the above two options, choose option 2.

3. Demonstration and selection of angle measurement module

Solution 1: The MCU integrates the nine-axis angle sensor ICM20600 to read the raw data, and then solves the attitude angle through quaternion.

Solution 2: The MCU reads the raw data from the MPU-6050 and the magnetometer, and performs Kalman filtering to obtain the Euler angle of the quadrotor.
The ICM20600 integrates a magnetometer, eliminating the increased system complexity caused by dual modules and reducing the amount of calculation of the MCU, so it was decided to adopt Solution 1.

4 Argumentation and selection of height modules

Solution 1: Use the spl06 pressure sensor to measure the atmospheric pressure at the current location and convert it into altitude by the microcontroller. Subtract the altitude value at departure to get the actual flight altitude. The pressure sensor has a wide measurement range (9000 meters to -500 meters above sea level), but the error is large.

Solution 2: Use US-100 ultrasonic sensor to measure flight altitude. Ultrasonic sensor has a small measurement range (2cm-450cm) and high measurement accuracy (0.3cm±1%).

Solution 3: Use the spl06 air pressure sensor, US-100 ultrasonic sensor, and openMV-M4, take the weighted value of the data collected by the three, control the flight altitude, and achieve hovering.
Considering the advantages and disadvantages of the above solutions, we adopt Solution 3.

5 Demonstration and selection of tracking module

Solution 1: GPS cannot be used in small indoor spaces;

Solution 2: Use the optical flow sensor ADNS-3080 to read the surface image, and adjust the aircraft's flight direction through analysis by the single-chip microcomputer to achieve the purpose of tracking. ADNS-3080 is more expensive, but it has high accuracy and fast response.
Solution 3: Use **openMV to read the surface image and capture the red light source, which has good effect and high efficiency.

Considering the advantages and disadvantages of the above solutions, we adopt solution 3.

2. Design and Demonstration

This system is an autonomous quadrotor tracking cruise system based on the Texas Instruments MSP-EXP432P401R microcontroller and Openmv image recognition as the monitoring solution. In terms of image processing, this system specifically targets the unstable characteristics of the aircraft's flight attitude. By collecting the aircraft's attitude angle, it performs horizontal relative distance compensation, thereby obtaining more accurate flight motion adjustments and realizing the aircraft's fixed-point hovering, target determination, and other functions.

1. Description of control method

1) Extract binary image

Since the background of the venue is white, it is necessary to identify red LED lights and black border lines, so the black blocks, red blocks and black lines in the picture can be directly searched. By obtaining the center coordinates of the target point and the length of the pixel mapped on the photosensitive chip and the flight altitude of the aircraft, the projection of the drone and the horizontal calculation of the target are calculated, and this coordinate is obtained and compared with the **center value as a variable to control the direction of movement of the aircraft. Use MSP432 to communicate with the flight control board through serial communication and send instructions to change the motion state of the aircraft. Use Openmv** to collect image data and binarize the collected pixels. At the same time, dynamic threshold and filtering algorithm are adopted while considering the performance of the single-chip microcomputer. Finally, the binarized data is stored in the corresponding image array;

2) Identify the boundary and calculate the return coordinates

Use Openmv to identify the black lines. At the beginning and end of the cruise, we can identify the black boundaries of the left and right areas. We fly slowly forward along the line and keep a certain distance from the left and right boundaries. We correct our heading by the number of pixels fed back by the black block. When we identify the black block in front of us, we slow down the cruise speed. When the number of pixels of the black block reaches the threshold, we start to deviate to the left, and then start to return. Repeat the above steps until we identify the black box, cross the black box, identify the red cross, and land smoothly.

2 Parameter calculation

1) Yaw axis height offset
The height of the aircraft is determined by the change in the size of the pixels in the ultrasonic wave and the image, and the vertical offset of the aircraft from the desired height is calculated;
2) Pitch axis and Roll axis horizontal offset
By measuring the coordinate value corresponding to the center of the color block when the aircraft is in the middle of the image, the horizontal offset corresponding to the front and back and left and right of the aircraft is calculated.
3) Control of the aircraft by the offset

The control idea is to use the offset to perform PID control on the aircraft. Due to the change of angle during flight, the obtained coordinates are compensated for the angle, and finally inertial navigation is realized using sensors such as gyroscopes and accelerometers.

3. Circuit and Program Design

1 System composition and block diagram

2 System Software and Process

Actual picture (not very good)

[Paper Attachment]

厂门大学队_灭火飞行器.pdf (567.53 KB, downloads: 37)

2021-8-4 22:02 上传

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