Posts

I had my first try at visualizing incoming data from the LIDAR last night. Good news is that it worked, and I got a successful SLAM map of the room. That’s pretty awesome. Bad news is I definitely have to redesign the pulley mechanism. Stepper motor is ridiculously loud, heavy and slow. I need to design a smaller pulley system that runs on an encoded DC motor. I used a Python library called BreezySLAM for the SLAM implementation. It really simplifies the amount of work you have to do. I had to do some figuring out on Python serial comms, but once I got the data from Arduino to Jupyter, I had the image rendered in a few minutes. Here is the relevant piece of code: ...

Now that I have successfully encoded the stepper motor position for LIDAR, I turned my attention to encoding the DC motors that I am planning to use for running the robot wheels. There are several good examples of this online, but most use quadratic encoders (DC motors with embedded dual encoders in them, usually magnetic). Unfortunately I don’t have any such motors at hand, and I have many, many DC motors so I am hesitant to buy more. ...

I finally ran into an issue that I have been dreading for a while: Encoding the actual position of the LIDAR pulley mechanism. Now that the LIDAR scan works, I need accurate position data alongside the measurements. As reliable as my ridiculously powerful stepper is, it’s not a servo and doesn’t know which position it starts from. There are various ways of solving this, with varying levels of budget and difficulty: ...

After a few days of struggling with stepper motor controls, I finally got everything working reliably last night. There were a lot of learnings along the way, most of them not very well explained on most tutorials I found online. My problem was essentially that I have a ridiculously powerful set of steppers. I kept referring to them as NEMA-14, but while reading this guide from Adafruit, I learned that NEMA nomenclature doesn’t mean much other than enclosure size. ...

I got the stepper motor working tonight. This was significantly harder than I expected. I had several motor driver boards lying around, and thought I would make my job easier and use an Arduino Motor Shield. As it turns out, running steppers with it is not that straightforward. I tried several libraries, everything from the standard Stepper library to the AccelStepper, which is supposed to be state of the art. There are a few things that threw me off, in no particular order: ...