Cartesian Drawing Robot
Date : 01/02/2024
Introduction
Our group of three set out on a challenging mission with the goal of using technology to help us extend our knowledge in the field of electrical engineering, electronics & robotics and build a cartesian drawing robot. This blog article details our experiences over the four weeks of the project, highlighting the difficulties and successes we had along the way.
Components Used
Arduino UNO rev3 (potential use of raspberry pi 4 for image processing in the future), DFROBOT NEMA 17 Stepper Motors, Joystick, 4mm x 300mm Brass Rods, M8 threaded rods 300mm, Aluminum shaft couplers, ultrasound sensors, M8 threaded nuts, a4988 stepper motor drivers, L298N DC motor driver (wasn't the right driver to give us precise control of the stepper motors), 3D printed parts for corners/holding the stepper motors/sensors.
Week 1
The Arduino, ultrasound sensors, joystick, stepper motors and L298N drivers had arrived in time for week 1. Using the Arduino we tested ultrasonic sensors, joysticks and the L298N motor driver.
We ran into our first issue with the project, that being that the drivers we had got could work for stepper motors, but would not give us the fine control needed with our project. They would run similar to a DC motor in this configuration. To solve this issue, we decided to order a new set of drivers called the a4988, which were specifically made to work with stepper motors.
We also decided to run the stepper motors in full step mode as our threaded rod had a very low pitch so one full rotation would be 200 steps, and it would take roughly 150 turns to get from one end of the rod to the other end.
Week 2
As the new stepper motor drivers had arrived, we were able to test the stepper motors working in conjunction with the sensors and joystick. The CAD design of the pieces to be 3D printed was also started on this week. This however went through a lot of design changes.
Due to having the main electronic components, the code to control the motors could also be started. Testing with how moving the joystick could turn the motors were also implemented.
Faced issues working with the stepper motors as it was our first project using such devices. The joystick was inaccurate due to which we had to change the unit.
Date : 15/02/2024
Week 3
This week saw us complete the 3D modelling of the blocks and also print out a few extra blocks such that it could be used for testing and also as backup. Compared to the previous weeks, our motor was less jittery and working as expected. We also managed to write the code that controlled the movement of the pen (use a more technical term here) and also updated our weekly blog and included the progress made each week. Managed to fix the problem of the Arduino's clock speed being slow which was to read the sensor and move the motors at the same time.
Date : 22/02/2024
Our main objective for the last lab session for this project was to test whether the cartesian drawing robot was functioning as expected. The 3D blocks were glued to the rods using a hot glue gun and a few extra wires were soldered onto the Veroboard. We also taped the wires together to make it more presentable and tidy.
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