USB radar, build your own missile defense system

Everyone has seen radar (at least on TV). It feels great every time I see it. It can detect various obstacles. It would be great if I could have one.

But there is someone who not only dares to think, but also dares to put his ideas into practice (which is what we lack), and he really made a very cool USB radar.

This is its appearance. It looks a little simple, but it is quite fun to play with it.

This foreign enthusiast not only made this circuit, he also wrote a very beautiful host computer to achieve the purpose of computer control.

How about it? Doesn’t this interface look like a real radar? Anyway, I was attracted by this interface.

So how can we have a USB radar like the author's?

First, let's talk about the overall framework. In fact, this USB radar is very simple in principle. It consists of an ultrasonic module installed on a stepper motor, a PIC microcontroller, and of course the stepper motor drive circuit.

PIC microcontroller
The driving circuit drives the stepper motor to rotate, and receives the echo signal sent by the ultrasonic module installed on the stepper motor to obtain the position of the obstacle in front, and then sends it to the upper microcomputer software through USB. The upper computer software calculates and displays each obstacle graphically.

The specific driving circuit is actually very simple, consisting of two H bridges. (If you find it troublesome, I think it can also be realized with L298).

But the author was not satisfied with this, he also bought a USB missile from the store.

How about missiles + radar... it becomes the Patriot missile defense system...

In order to make the two devices work better together and make this project more fun, the author modified the host computer program.

After adding the missile, this project becomes more interesting. But it is also a little more complicated to operate.
It seems that the USB missile that the author bought does not have feedback, that is, it does not feedback the rotation angle, so it is much more troublesome to use. It is recommended that when you make this, the missile should also have feedback, just like the base of the radar.

Since there is no feedback, we cannot know the direction of the missile, but we can calculate its position through its speed and rotation (but this may have errors). And at the beginning we need to adjust the position of the missile to the same direction as the radar.

The operation of the author's software is as follows: first, start the USB radar, rotate 360 ​​degrees, and click the Scan environment button on the software. The software will draw the trajectory of the obstacle in the picture (imagine that the radar is surrounded by a wall. After scanning, the trajectory of the wall will be displayed). Moreover, due to the scattering of ultrasonic waves and other reasons, this trajectory is not accurate. The software will automatically make a correction to get the final detection range.

Now, if there is a target within the detection range (the area surrounded by the red curve in the figure), the software will control the missile to rotate to the nearest target and attack it! Unfortunately, we have lost the direction of the missile again. We can only determine the current position of the missile by measuring the time it takes for the missile to rotate to the target and the set speed. If it rotates too much or too little, we need to correct the speed of the missile's rotation.

Note: This radar is quite interesting. In fact, I think the stepper motor below can be replaced with a general DC motor + reduction box. Through some simple feedback, such as driving a certain potentiometer when rotating (actually the principle of the servo), and then the microcontroller detects the voltage on the potentiometer to get the position information of the motor. In this way, the stepper motor can be omitted, because the drive of the stepper motor is still quite troublesome, and the DC motor only needs an H bridge to use PWM speed control. In addition, if you want to make a missile, it is best to make it with feedback.
I wonder if you have any other novel ideas? For example, if it is made in two dimensions, you can get a surface curve, which should be more interesting (you can scan the curve on the surface of an object and simply judge what it is).