Line-us: An ESP8266-Based Drawing Robot

Reporting from Shanghai, China
Jan 26, 2021

A startup in London has created a small ESP8266-based robotic arm that draws with a real pen.

Line-us is an internet-connected drawing robot that started as a Kickstarter campaign back in 2017. Ever since, Line-us robots have been sold online and in retailers. Line-us is small, portable and draws using a real pen on paper. Actually, it replicates whatever you draw on a touchscreen, using the free app that goes with Line-us. But you can also send messages with it, share sketchbooks or collect artworks from others!

Apart from its own drawing app, Line-us also has programming APIs for many languages, such as Python, Processing, Java, Javascript, etc. This way, you can control the drawing app with your own code. Line-us is built around the ESP8266 microprocessor, thus showcasing how capable Espressif’s MCU is, as it enables the drawing robot to perform all of the following:

    • Connect to Wi-Fi, in ST mode, or AP mode if there is no Wi-Fi available.
    • Manage a TCP-sockets API and a Websockets API. 
    • Parse and interpret the GCode sent by the drawing app with the default code or with the user’s own code.
    • Compute the inverse kinematics and do motion planning.
    • Control the servos in real time.
    • Periodically check with the back-end to see if anyone has sent the user a drawing.
    • Use the local filesystem to store up to 20 drawings, so that users can draw in standalone mode without the app or Wi-Fi.

In fact, Line-us is neither a plotter nor a printer. The magic bit is that Line-us draws in exactly the same order users do, because it mimics their motion with a pen and recreates whatever they draw on screen.

Draw or write with your finger, mouse, stylus or Apple Pencil, and follow that in real time, as Line-us copies your movements. Then, save and share your drawings to start communicating with other Line-us robots!

Just connect it to a USB battery or power supply and you are ready to go. Line-us comes with a small metal plate to hold it in place. You can use it on any writable surface: in your sketchbook, diary, notebook or just a piece of paper.

The Line-us app helps you interact with your own Line-us robot, and see what other people have shared with you. The app lets you create, save and share drawings. The app works on iPads, iPhones and Android. It also works on both Mac and PC.

Line-us becomes magical when it connects to the internet and talks to the community of other such machines. It can talk using another language too. So, if you're in to coding, you should take advantage of the easy interface Line-us has for talking to Scratch, Arduino, Raspberry Pi, Python and Processing.

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