BrowserBot – Browser-Controlled Robot

Overview

Have you seen projects where a robot is controlled by a phone, tablet, or computer over the internet? BrowserBot lets you do exactly that — quickly and easily. It is a simple example project that demonstrates how to drive a BrickPi3 LEGO robot through any modern web browser using on-screen buttons or keyboard shortcuts.

The Raspberry Pi runs a lightweight Python Tornado web server that serves the control page and relays WebSocket messages to the BrickPi3 motors in real time. No app installation or pairing is required — just open the IP address of your Raspberry Pi in a browser.

How It Works

BrowserBot uses WebSockets to pass messages between your browser and the robot:

1. The Tornado server on the Raspberry Pi serves Browser_Client_Code.html — the control page.
2. You open that page on any device on the same network.
3. Pressing the on-screen arrow buttons (or the corresponding keyboard keys) sends a WebSocket message to the server.
4. The server receives the command and calls the BrickPi3 API to set motor speeds accordingly.
5. Releasing a button sends a stop command, halting the motors immediately.

An optional camera streaming add-on (stream_server.py + streaming_client.html) lets you view a live video feed from the Raspberry Pi Camera in the same browser window.

Parts Required

• BrickPi3 (Base Kit or Core Kit)
• Raspberry Pi (Pi 3 or Pi 4 recommended)
• 2 × LEGO EV3 Large Motors (for drive wheels)
• LEGO structural parts for the robot chassis
• microSD card with Raspberry Pi OS Trixie for BrickPi3
• 12 V battery pack for BrickPi3
• Wi-Fi connection (robot and controlling device must be on the same network)
• Optional: Raspberry Pi Camera Module for live video streaming

Motor Connections

Connect the drive motors to the BrickPi3 motor ports:

• Left drive motor → Motor Port A
• Right drive motor → Motor Port D

If you use different ports, update the port constants at the top of RPi_Server_Code.py before running.

Software Setup

1. Install the BrickPi3 libraries

If you're using Raspberry Pi OS Trixie for BrickPi3 the libraries are already installed. Otherwise, follow Option B from the Installation FAQ.

2. Install Tornado

Tornado is the Python web framework used by the BrowserBot server:

sudo pip install tornado

3. Run the server

Navigate to the BrowserBot project folder (inside the BrickPi3 repository cloned in step 1):

cd ~/BrickPi3/Projects/BrowserBot
sudo python RPi_Server_Code.py

The server starts on port 9093 by default. You should see a message confirming it is listening.

4. Open the control page

On any device connected to the same Wi-Fi network, open a browser and go to:

http://<raspberry-pi-ip>:9093

Replace <raspberry-pi-ip> with your Pi's local IP address (find it with hostname -I). The BrowserBot control page will load with forward, back, left, and right buttons. You can also use the W / A / S / D or arrow keys on a keyboard.

5. Optional: Live camera stream

To add a live video feed, run the streaming server in a second terminal:

sudo python stream_server.py

Then open streaming_client.html in your browser to view the feed alongside the controls.

Source Code

All source code is free and open source on GitHub:

• github.com/DexterInd/BrickPi3 – Projects/BrowserBot

Key files in the repository:

• RPi_Server_Code.py — Tornado WebSocket server; handles motor commands
• Browser_Client_Code.html — the control page served to browsers
• camera_streamer.py — captures frames from the Pi Camera
• stream_server.py — streams camera frames over HTTP
• streaming_client.html — browser page that shows the live feed