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Author: Fengse Mengchen from Aofei Temple

A guy on YouTube recently had a problem: My wife is very good at archery, but I am a bad guy and want to win . What should I do?

6 months of hard training, 6 years? No No No, it’s better to spend time making an automatic aiming bow and arrow, once and for all!

This is how this DIY guru thinks . Damn the desire to win.

I have to say that it took the little brother 6 weeks to actually make it. In the end, the bow and arrow went straight to the target like a dog meeting a meat cat meeting a mouse and a rabbit meeting a carrot.

You can hit it without looking :

Change to an apple, no problem:

Even moving targets can hit the target perfectly:

As soon as the video was uploaded to YouTube, it attracted millions of netizens to watch. "Brilliant", "Incredible", and "Awesome" were all over the place, and the voices of admiration were endless.

Of course, in order to win his wife, I have never thought of cheating by buying an auto-aiming bow and arrow, but unfortunately they are not sold online.

As a hard-core engineer + programmer, I cannot allow this kind of thing to happen in 2021. I must do it myself!

Part circuit algorithm is all self-made

First, buy a lightweight bow. After all, you have to add a lot of parts to it. If it’s too heavy, you won’t be able to lift it.

I have already thought about the idea of ​​automatic aiming:

First there is an automatic aiming device that is responsible for moving the bow, and then there is an automatic release device that automatically releases the arrow at the timing determined by the system .

The vision system for aiming consists of 8 high-speed cameras that can be updated 50 times per second.

Except for the purchased bow, arrows and camera, other parts are designed and made by myself, the circuit is welded by myself, and even the aiming algorithm is written in Python by myself.

It’s really all-powerful.

After everything is done, the up and down, left and right directions can be automatically adjusted, and no one needs to worry about the launch timing.

Finally done, let’s test it on the target.

Uh... I won't say whether it's accurate or not, because the timing of the bow moving to the right position is unpredictable, and the hand that pulls the bow will always hit itself in the face if it is automatically launched off guard.

The younger brother later explained that actually this problem can be avoided by drawing the bow fully. However, during the test, in order to avoid the arrow being shot too powerfully and inadvertently damaging other items in the room, I had to sacrifice myself by drawing the bow half full.

Let’s take a look at the accuracy.

It's a bit off, and it always goes to the upper left.

Although there is a simple way to solve this situation: artificially add a correction and aim a little lower to the right every time.

My brother’s years of development experience told him that doing so would pave the way for more bugs in the future.

But I can’t worry about that much. Let’s temporarily add this “very stupid correction” and call my wife over for a competition.

The result was... a complete defeat 0:3 .

He was unwilling to give in. Everything was normal but the arrow was a little bit off. That must be a problem with the code .

In addition, we still have to tame the moving target . Instead of modifying the code, it is better to delete it and rewrite it, so I coded for another week.

OK, try again.

Pulling up the bow, "Ahem, my wife is throwing a target":

The little brother pressed the start button, and the tracking system did the rest:

Every 300 milliseconds, the system checks the parabolic trajectory of the target's movement and sends it to the computer, which then uses a "tedious" little calculation to determine where the bow will move, taking into account the time it takes for the arrow to reach the target and the curved path of the arrow.

As the data was updated, the bow kept moving, and finally it aimed at the right moment and fired an arrow:

Perfect miss...

There is still a problem with the code, please fix it!

It was agreed that it would only take one minute to repair, but it took me an hour . My wife said she was too lazy to wait.

No one gave him a target anymore, but that didn't stop him: just build another automatic target thrower .

According to the younger brother's later recollection, this target thrower was used to throw at least a thousand targets during the entire 6-week development process.

Okay, okay, try again!

emmm...either it was too early or too late, and it couldn't even hit the static target...

Bugs Bugs are all bugs. Even the target throwing machine has bugs. After repairing it again, it's still a little bit worse.

The little brother checked and confirmed that there is no problem with the machine and the automatic aiming system. What is wrong? He planned to change his mind.

In addition to technology, there is also krypton gold

The little brother discovered through the slow-motion replay of the arrow's flight, why didn't the arrow shoot ?

It turned out that the problem was not with the automatic aiming system, but with the entry-level recurve bow he bought .

According to the principle of the recurve bow, when the string is pulled hard, the arrow body will be slightly bent and deformed by external force. After the arrow is released and fired, the force on the arrow body is removed, and it will tend to return to its original shape under the action of elastic recovery force .

This force will bend the arrow body in the opposite direction and change the arrow's flight direction. If it bends in the opposite direction to a certain extent, it will rebound again and change its flight direction.

I figured this out by referring to a video from another YouTube channel, SmartEveryDay.

In this repeated cycle, the arrow does not shoot straight towards the target, but keeps swinging forward.

In professional archery, the degree of bending resistance of an arrow is called "spine . " The deflection also affects the degree of sway of the arrow during flight. Bows of different pounds must be matched with arrows of different deflections to easily hit the target.

The little brother feels that although this problem can be solved by strengthening the algorithm and taking the deflection into consideration, this does not fit in with his wild Iron Man style.

After all, Iron Man not only knows technology but also has money.

The little brother decided to make money ! Buy a compound bow that can shoot arrows straight .

After moving the aiming device to the compound bow, the problem I was worried about at first really appeared: the whole system is too heavy to lift.

But this didn't bother him. The little brother got himself a set of armor and used the strength of his entire upper body to support the weight of the bow.

At this time, the entire system can be said to have evolved from an automatic aiming bow to an aiming robot , and the only task left for humans is to draw the bow.

Find a wife to compete with again!

In order to win more steadily, I also adjusted to the precision mode and waited for the aiming device to completely stop moving before firing.

This time they won 3:0 .

But I wasn’t satisfied yet, so I challenged the moving target again and succeeded!

The next more difficult challenge is whether you can shoot the super small "apple" on the head of the Lego minifigure.

How small is it? The diameter is not as large as the arrow shaft .

Judging from the results, although it can be shot, the Lego minifigures are consumed very quickly.

The next challenge is to go further

This guy’s name is Shane Wighton. He has worked as an engineer for a 3D printer company (Formlabs) in the United States for eight years. He has a bachelor’s degree in mechanical engineering and a master’s degree in computer science.

Although the school he graduated from is not very famous (University of North Carolina at Charlotte) , he has been welding plastic models under the leadership of his father since he was four years old .

Talented and passionate about production, he has resigned from the company and now seems to be working as a YouTuber full-time.

Since his channel was launched during the epidemic last year, the total number of subscribers has exceeded 3 million in less than a year and a half .

There must be many people who have seen his works.

Just like this automatic hair clipper:

There are also this kind of basket and billiard cue that are always accurate (it seems that I am a little obsessed with automatic aiming) :

Finally, back to the automatic bow and arrow. Although Shane thinks the current effect is cool enough, what he wants is to compete with real archery masters.

Next, he has the challenge of shooting an apple on the head of a Lego minifigure from a distance of 45 meters .

Because distance will amplify small deviations, to achieve this goal requires the development of a new generation of automatic aiming bows.

The improvement method has already been designed in his head.

Original video address:
https://www.youtube.com/watch?v=1MkrNVic7pw

Reference links:

[1]https://bowaddicted.com/how-to-properly-tune-a-recurve-bow/
[2]https://www.youtube.com/watch?v=O7zewtuUM_0
[3]https:// www.patreon.com/stuffmadehere

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