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Roslite.js

Hi everyone,
I was toying around with the idea of having an entire robot’s processing within a webpage – both for the purpose of educational simulations, as well as using phones as the brains of a simple robot without going through the mess that is native programming.

So I came up with this prototype of roslite.js – at the moment it’s just a publisher/subscriber interface:

Here’s a demo of it in action, intended to be run on an Android phone, that contain 4 nodes. Note that all nodes run in a single thread in an event-driven fashion.

  • imu_node, which publishes the phone’s IMU data to /imu/data
  • gps_node, which publishes the phone’s GPS data to /gps/fix
  • echo_imu, a node that subscribes to /imu/data and echoes to the web page
  • echo_gps, node that subscribes to /gps/fix and echoes to the web page

Demo (it will ask you for location permissions, for GPS):
https://dheera.github.io/roslite-demo/

Other ideas for nodes:

  • A motor node! Use the phone to control motors over Bluetooth using the web bluetooth API, as I have run here, although this doesn’t yet use roslite.js: https://github.com/dheera/robot-tethys/
  • Motor node that control motors using the headphone out port for left/right PWM signals, or over Wi-Fi to an IP-based motor controller
  • Bluetooth access to a million other BLE sensors
  • Access to IoT sensors over Wi-Fi
  • Camera node that just uses the phone’s camera

In short, I feel like a full-blown robot brain could be made from within the web browser.

Questions to the community:

  1. Do you find roslite.js interesting? If so, why?
  2. Do you see value in writing robotics code in JavaScript?
  3. At the moment it’s just a publisher/subscriber interface, but what other features from ROS would you want to have in something like roslite.js? e.g.
  • tf2
  • service calls
  • visualization tools for simulated educational robots in the browser
  • console commands, e.g. rostopic echo, rostopic pub, rosnode list, etc.
  • parameter server
  • ability for a centralized server to connect to multiple remote ROS masters running on phones
  • infrastructure to offload processing loops of nodes to Web Workers (downside: web workers can’t access the UI or sensors, but they can do heavy lifting e.g. simple SLAM algorithms) – note that ALL nodes run together in a single thread if you don’t use Workers so you need to avoid blocking operations
4 Likes

Did you take a look at https://github.com/RobotWebTools/roslibjs/? You can use it to talk to a ROS system from your browser. It supports topic, services actionlib and much more.

If you did, what are the differences?

Hi @Rayman
I’ve used roslibjs and rosnodejs extensively, yes – this is for a completely different purpose. The key difference here is that roslite.js (a) isn’t ROS and doesn’t connect to a ROS master, but (b) follows a few basic ROS paradigms and allows you to have the entire robot, including “roscore” itself, inside the browser as well… Also, it does not use any inter-process communication – all nodes run together in a single thread and directly pass JavaScript objects to each other, but the idea is to follow the ROS standard data types.

It isn’t designed to replace ROS for bigger and more complex robots, but I’m thinking that a lot of educational simulations+visualizations and phone-driven robots may benefit from the ability to have everything run self-contained inside a browser.