Water Related

River Water Surface Floating Material Monitoring System

PR012

Rui You (Chengdu University of Information Technology)

Apr 03, 2022 2392 views

River Water Surface Floating Material Monitoring System

River water surface floating object monitoring system uses sonar probe to transmit and receive sound waves as the front end of the system detection. When working, the master control device controls the sonar probe to transmit a certain frequency wave, when there is a floating object in a specific area, the wave transmitting forward meets the obstacle and will be reflected to the sonar probe, the master control device can calculate the distance s from the sonar probe to the floating object according to the time difference t from transmitting to receiving and the propagation speed v of the wave in the water, and the properties of the floating object can be judged by analyzing the difference between the return wave and the transmitting wave. At the same time, the main control device receives the information returned by the sonar probe, controls the camera device to shoot down the image of the specific area, and transmits all the above information to the cloud through the wireless transmission device. The function of monitoring floating objects on the water surface of the river is completed.

Project Proposal


1. High-level project introduction and performance expectation

Project Background:

Traditional water environment monitoring instruments and equipment focus on water quality, water pollution, monitoring and alarm of harmful substances in water body, early warning of water level and collection and alarm of water flow rate. At present, such equipment can achieve unattended, automatic data processing, automatic alarm and other functions. However, the equipment for monitoring and automatic alarm of floating objects on the water surface is still imperfect, and it is still in the research stage at home and abroad.

Design Objectives:

The system mainly detects and alarms the solid waste and duckweed of various lakes and rivers, especially narrow rivers, beaches and lakes and ponds in the scenic spot, and sends the processing results of relevant systems to the cloud.

2. Block Diagram

Block Diagram

The river surface floating object monitoring system uses sonar probe to transmit and receive sound waves as the detection front end of the system. Fix the sonar probe on the motor, and FPGA controls the rotation of the sonar probe through the motor to scan the specific area of the river; Or use phased array technology and sampling electric scanning method to realize fast scanning. During operation, FPGA controls the sonar probe to transmit a wave of a certain frequency. When there is a floating object in a specific area, the wave will be transmitted forward and encounter obstacles and will be reflected to the sonar probe. FPGA can calculate the distance s from the sonar probe to the floating object according to the time difference T from transmission to reception and the wave propagation speed V in the water, and then according to the position of the motor θ, Determine the spatial position of floating objects; By analyzing the difference between echo and transmitted wave, the properties of floating objects can be judged. At the same time, after receiving the information returned by the sonar probe, the main control device controls the camera to capture the image of a specific area, and transmits all the above information to the cloud through the wireless transmission device. Complete the function of monitoring floating objects on the river surface.

3. Expected sustainability results, projected resource savings

1. Complete the processing of echo signal and generate echo image;
2. Take pictures of the river and upload them to the cloud through wireless transmission;
3. Classify and identify floating objects through echo signals;

4. Design Introduction

设计目的利用声呐的探测原理,实现了对水面异常漂浮物的探测和基本信号处理的功能。设备体积小巧,便于安装。主要针对各种湖泊河道,尤其是狭窄河道、滩涂及景区内的湖泊、池塘的固体垃圾、浮萍等检测报警,以及在危险区域进行远程作业,提高安全性和高效性。

应用范围:城市河流干道

intel FPGA在本系统起着信号处理、整机时序控制以及声纳传感器驱动的功能。FPGA是雷达信号处理模块及发射机上常用的器件,依靠verilog硬件描述语言的并行优势以及成熟的IP核,可以方便开发者快速开发工程。

5. Functional description and implementation

上图为FMCW测速及测距的概念图。因为光速远大于目标物移动速度,在求目标物距离时可将目标物视作静止即忽略目标物的移动速度。若要获得目标物的移动速度,须对线性调频连续波雷达信号的进行二维处理,首先要积累多个周期的回波。那么回波应该按照如所示的周期排列成二维矩阵。通过二维矩阵的快速傅立叶变换,可以获得与目标的距离和速度相对应的频率信息。

 

6. Performance metrics, performance to expectation

根据资源评估,初步判断,intel的飓风五代完全可以驱动PGA460,外加完成信号处理、时序控制等模块,现初步可以获得距离信息,但是速度信息还无法获得。

7. Sustainability results, resource savings achieved

整个系统工作流程如下图所示,开机后进行系统初始化,若初始化失败则发送指令给上位机,若成功则进行系统自检,之后解析上位机发送的指令,根据指令设置波形参数和驱动配置,之后接受采集到的回波并对回波进行信号处理,处理完后发送给上位机,等待下一波回波信息处理或者关机。

 

产生线性变频信号,频率为 38khz~42khz 的方波,每个频点发射 10 个周期,循环一次的总时长为 31.6008ms。
 频点数即为定时器周期数,N= Fclk/Fout,仿真时 SingalGen 模块输入时钟信号为 100M,  
所以频点数为 2382 到 2632 即对应频率为 38khz~42khz;

 

上图为发射信号RTL视图,将更改计算过后的频点数送入DDS模块,由此产生线性调频信号。

 

上图为其对应的modelsim仿真。

 

上图为信号处理流程,将采集到的模拟信号通过FIFO缓存,之后经过DDC模块进行数字下变频,之后对复数信号进行FFT变化,将结果存入RAM中等待下一步处理。

8. Conclusion

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