Laser device for neutralizing - mosquitoes, weeds and pests (in progress)

Here I will post information for creating a laser device.

A warning!!

Don't use the power laser!

The main limiting factor in the development of this technology is the danger of the laser may damage the eyes. The laser can enter a blood vessel and clog it, it can get into a blind spot where nerves from all over the eye go to the brain, you can burn out a line of "pixels" And then the damaged retina can begin to flake off, and this is the path to complete and irreversible loss of vision. This is dangerous because a person may not notice at the beginning of damage from a laser hit: there are no pain receptors there, the brain completes objects in damaged areas (remapping of dead pixels), and only when the damaged area becomes large enough person starts to notice that some objects not visible. We can develop additional security systems, such as human detection, audio sensors, etc. But in any case, we are not able to make the installation 100% safe, since even a laser can be reflected and damage the eye of a person who is not in the field of view of the device and at a distant distance. Therefore, this technology should not be used at home. My strong recommendation - don't use the power laser! I recommend making a device that will track an object using a safe laser pointer.

How It Works

To detect x,y coordinates initially we used Haar cascades in RaspberryPI after that yolov4-tiny in Jetson nano. For Y coordinates - stereo vision.
Calculation necessary value for the angle of mirrors.
RaspberryPI/JetsonNano by SPI sends a command for galvanometer via DAC mcp4922. Electrical scheme (here). From mcp4922 bibolar analog signal go to amplifair. Finally, we have -12 and + 12 V for control positions of the mirrors.

General information

The principle of operation

Single board computer to processes the digital signal from the camera and determines positioning to the object, and transmits the digital signal to the analog display - 3, where digital-to-analog converts the signal to the range of 0-5V. Using a board with an operational amplifier, we get a bipolar voltage - plus and minus 5 V, from which the boards with the motor driver for the galvanometer are powered - 4, from where the signal goes to galvanometers -7. The galvanometer uses mirrors to change the direction of the laser - 6. The system is powered by the power supply - 5. Cameras 2 determine the distance to the object. The camera detects mosquito and transmits data to the galvanometer, which sets the mirrors in the correct position, and then the laser turns on.

Dimensions

1 - PI cameras, 2 - galvanometer, 3 - Jetson nano, 4 - adjusting the position to the object, 5 - laser device, 6 - power supply, 7 - galvanometer driver boards, 8 - analog conversion boards

Galvanometer setting

In practice, the maximum deflection angle of the mirrors is set at the factory, but before use, it is necessary to check, for example, according to the documentation, our galvanometer had a step width of 30, but as it turned out we have only 20
Maximum and minimum positions of galvanometer mirrors:
a - lower position - 350 for x mirror;
b - upper position - 550 for x mirror;
c - lower position - 00 for y mirror;
d - upper position - 250 for y mirror;

Determining the coordinates of an object

X,Y - coordinate

Z-coordinate

We created GUI, source here. At the expense of computer vision, the position of the object in the X, Y plane is determined - based on which its ROI area is taken. Then we use stereo vision to compile a depth map and for a given ROI with the NumPy library tool - np.average we calculated the average value for the pixels of this area, which will allow us to calculate the distance to the object.

Determining the angle of galvanometer mirror

angle of galvanometer mirror theory

The laser beam obeys all the optical laws of physics, therefore, depending on the design of the galvanometer, the required angle of inclination of the mirror – α, can be calculated through the geometrical formulas. In our case, through the tangent of the angle α, where it is equal to the ratio of the opposing side – X(Y) (position calculated by deep learning) to the adjacent side - Z (calculated by stereo vision).

angle of galvanometer mirror practice

Demonstrations

In this video - a laser (the red point) tries to catch a yellow LED. It is an adjusting process but in fact, instead, a yellow LED can be a mosquito, and instead, the red laser can be a powerful laser.

Publication and Citation

Ildar, R. (2021). Machine vision for low-cost remote control of mosquitoes by power laser. Journal of Real-Time Image Processing
availabe here
Rakhmatulin I, Andreasen C. (2020). A Concept of a Compact and Inexpensive Device for Controlling Weeds with Laser Beams. Agronomy
availabe here

Contacts

For any questions write to me by mail - [email protected]

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laser_control's Introduction