SID Project

A Robotic project - Stereo Imaging Device

Project participants

• Nicolas SAMELSON 17288
• Raphaël JADIN 21295
• Gabriel LOHEST 16205

Introduction

The goal of this project was to design a 3D scanner, develop an interface and scripts to output the scanned object into a 3D STL file, ready to import into a 3D CAD design software.

This project is still in a phase of a prototype and therefore not a finnished product.
All the files for the interface, the script, the PCB and the 3D CAD designs were developped in an "Open-Box" extensibility model. The main branch contains the code, the pcb branch contains the PCB design files and the 3D-printed-hardware-CAD branch contains the models to print.

1. Material used

• 2 Raspberry pi 4
• 2 Raspberry pi camera (module V2.1)
• 1 Stepper motor (Nema 17 10:1)
• 1 driver (A4988)
• 1 Power supply AC/DC 5V and 12V
• 1 display 11"
• 1 red line laser (HLM1230)

2. Interface (Kivy)

The interface files are stored inside the folder /code/screen/. Inside, there are 4 files, each for a specific screen interface.

2.1. HomePageScreen

This corresponds to the home page of the interface. The user is presented with 4 buttons :

• Run, to access the RunScreen;
• Settings, to access the SettingsScreen;
• Storage, to access the StorageScreen;
• Exit, to exit the application.

2.2. RunScreen

This interface contains all the quick parameters to set before a scan and the button to start a scan :

• Resolution is used to set the number of pictures taken;
• Scale is used to set the size of the object to scan;
• Laser power is used to adjust the intensity of the laser;
• The set of 3 radio buttons helps visualize the pictures taken in different color spaces.

2.3. Settings

This interface is used to setup the calibration needed to scan (only the first time the application is launched) :

• Connect helps setting up the video stream of the slave raspberry pi camera;
• Slave(L) and Master(R) are used to have a video feedback of the 2 cameras;
• Capture/Calibrate launches the script of calibration.

2.4. Storage

The storage interface helps the user to manage its scans, as well as convert it in a 3D STL file.

3. Scripts

3.1. Main.py

Run the script main.py to launch the interface

3.2. On the Raspberry pi Master

3.2.1. Different Files

In the /code/raspberry/ folder, you can find the following scripts :

• GPIO_setup.py : used to set the correct pins in read/write at the start of the application;
• copy_slave_pics.py : after a scan , the master will copy the pictures taken by the slave in its own folder;
• laser.py : used to turn on/off and adjust the intensity of the laser;
• prise_image_bon.py : takes a picture from the master and writes it into a folder with the name of the scan;
• scan.py : main script that manages the scan (turns the laser, takes pictures, turn the stepper and copy the slave pics);
• sshTools.py : used to run commands from the master to the slave via the SSH protocol;
• stepper.py : used to command the stepper and turn a determinated number of steps;
• stream.py : used to command the slave to stream its video feed through rtsp.

3.2.2. Stereovision Folder

The stereovision folder contains the scripts to calibrate the cameras, but also to transform the pictures in a cloud of 3D points :

• calibration.py: calibrates the cameras;
• prepross.py: generate a new binarized image with in white the laser and the rest in black
• image_processing.py: contain the stereovision methods
• scan_processing.py: run the stereovision methods on a scan and then generate a JSON file with the world coordinates in the opencv calibration referential.
• post_processing.py: achieve the revolution of all the laser lines and save the point cloud to a json.
• jsonTools.py: Library to create json files and get data from json files
• mathTools.ty: Library with mathematical functions for the image processing

3.2.3. Post-processing Folder

This folder contains the scritps to transform a cloud of points into a 3D STL file :

• create_stl.py : takes in input a json file in a 3 dimensions matrix and outputs a STL file;
• create_points.py : creates json files to get examples of working models.

3.3. On the Raspberry pi Slave

• prise_image_bon.py: take picture and save it into the asked folder. Runned from the master in ssh.

4. PCB design

The pcb branch contains the Gerber files to print through JLCPCB.
You can find the scematics and the design in the pdf folder.

The point of this PCB is to have one board, connecting all the needed cables as well as having easy access to the pins. It contains a footprint for :

• A A4988 driver;
• 2 USB-A 2.0 female ports;
• 1 capacitor (12V)
• 1 potentiometer
• pins for the stepper, the alimentation (5 and 12V), the laser and the raspberry pi (master)

5. Continue the project

Please Fork the repository if you want to continue our project. If you just want to test it, just clone it.

5.1. Dependencies

The project needs you to have a python version of 3.8.10 or older, with the following pip modules installed :

• numpy
• numpy-stl
• opencv-python
• mathutils
• kivy
• RpiMotorlib