{"id":9553,"date":"2024-10-27T22:56:59","date_gmt":"2024-10-27T21:56:59","guid":{"rendered":"https:\/\/dronesonen.usn.no\/?p=9553"},"modified":"2024-10-28T14:22:14","modified_gmt":"2024-10-28T13:22:14","slug":"toyzrgone-week-8","status":"publish","type":"post","link":"https:\/\/dronesonen.usn.no\/?p=9553","title":{"rendered":"ToyzRgone \u2013 Week 8"},"content":{"rendered":"\n
\n
\n

Welcome back to our 8th ToyzRgone blogpost!<\/strong> Below, you will find the contributions made by each of our team members either individually or in pairs:<\/strong>
<\/p>\n<\/div>\n<\/div>\n\n\n\n

\n
\n

Philip Dahl<\/strong> \ud83d\udd0b<\/h2>\n\n\n\n

Communication<\/strong><\/p>\n\n\n\n

The main goal to start this week off, was to establish communication between Arduino and Raspberry Pi. Since everything stepper related has been run and tested through Arduino up until now, Hamsa and I decided that getting the Pi to control the Arduino directly would save us some trouble.
For this we used serial communication, more specifically I2C, by connecting them to each other through serial port. The hopeful attempt quickly turned to cheers as we had established communication for the \u201cArduPi\u201d. <\/p>\n\n\n\n

Motors<\/strong><\/p>\n\n\n\n

I acquired the 4th and final driver for the stepper motor. The one that was available was a TB6612FNG H-bridge which is a different driver from the A4988, used for the other 3 steppers. This driver is primarily designed for dual DC motor control, but the difference is really just the pins connecting to the Arduino.I found the schematic for connecting the driver to the Arduino and a brief explanation from this page:<\/p>\n\n\n\n

https:\/\/itp.nyu.edu\/physcomp\/labs\/motors-and-transistors\/lab-controlling-a-stepper-motor-with-an-h-bridge\/<\/a><\/p>\n\n\n\n

<\/p>\n\n\n\n

The PWM A and B pins normally control the speed of any connected DC motors, but the \u201cStepper\u201d and \u201cAccelStepper\u201d libraries in Arduino have designated functions for setting and controlling speed. Therefore, the PWM pins connect straight to Vcc (5V).<\/p>\n\n\n\n

While testing the newest driver, we discovered that one of the steppers (Back Right) is single stack, whereas the rest are double stack. This means that the single stack motor has less torque than the others and was the reason it was behaving slightly different to the same inputs.<\/p>\n\n\n\n

\n
\n

<\/p>\n\n\n\n

We have had an issue with connecting one of the steppers up properly for a while, as there are no available cables with connectors that fit. Normal female breadboard wires were just falling off, so we had to find a momentary solution while ordering the required cable. Hamsa was able to get in touch with Rasmus, who had access to the 3D-printer on campus. I gave him one of the connectors for reference, and so began a back-and-forth process of printing and shaping the printed piece to fit the stepper. This would have to be picked up again next week.<\/p>\n<\/div>\n\n\n\n

\n
\n
\n
\"\"
Marked Stepper motor withred. (Single stack with 3D
printed 6pin connector)<\/strong><\/figcaption><\/figure>\n<\/div>\n\n\n\n
\n
\"\"
The people’s favorite<\/strong><\/figcaption><\/figure>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n\n\n\n


Hamsa Hashi<\/strong> \ud83d\udcbb<\/h2>\n\n\n\n

This week, we worked on integrating the motor control for the robot using an Arduino Mega 2560 connected to the Raspberry Pi. By using the Arduino to control the stepper motors, we avoided challenges related to problematic libraries and dependencies on the Raspberry Pi. This decision also made it easier for Philip and me to collaborate, as we both have experience with C++.
To organize the work, we divided the task into steps.<\/p>\n\n\n\n

\n
\n


Step 1:<\/strong> Control the robot with a game controller to verify that both the code and the stepper motors behaved as expected. This turned out to be more complex than expected, as we discovered that the stepper motors were not identical, something Philip mentioned earlier in the blog.<\/p>\n<\/div>\n\n\n\n

\n
\"\"<\/figure>\n<\/div>\n<\/div>\n\n\n\n

We connected the Arduino Mega 2560 to the Raspberry Pi via USB, using the same serial port in Python and Arduino IDE (installed on the Raspberry Pi) to test the motors. I connected the game controller to python through import pygame for controlling the motors, allowing us to check if the planned logic for omnidirectional mobility worked as intended. Due to missing components, as Philip described, we improvised by suspending the robot so the wheels could move freely without shifting the robot. This allowed us to observe how the motors responded to joystick input and whether the response matched the expected omni-directional movement without risking the robot rolling away.<\/p>\n\n\n\n

\n
\n
\"\"
This is the first version of the omnidirectional robot control code using the AccelStepper<\/code> library. This code controls the NEMA 17 stepper motors without advanced features like Microstepping support, Smooth Start and Stop, Exact Angle Control, and fine-tuned Control of Direction and Speed. The motors are driven by simple speed calculations based on joystick input, lacking precise control for smoother and more accurate maneuvers.<\/strong><\/figcaption><\/figure>\n<\/div>\n\n\n\n
\n