/pendulum_simulator

Primary LanguageVue

Pendulum Simulator

Exexccuting project

You'll need dockerr and docker compose to run the project. But everything should be self contained.

> docker compose up --build

If using windows, I had difficulties with file permissions, but hopefully it should work. Deffinitly works on Ubuntu. Might also work on OSX.

Once the project is running on your local system, open a browser and go to [http://localhost:3000/]. You'll have to move the pendulums, there default positions are straight down, so they had no momentum.

  • Other behaviors, modifing any data on the frontend, automatically pauses the simulation.

Things that don't work correctly or I was too pressed for time

  • I didn't get time to work out immediate neighbors for the collision detection, so instead all pendulums check all other pendulums positions. This caused a race condition where all the process would detect the collision and proceed to SEND stop and RESTART, which I'm not confident I'm handling correctly.
  • I could better optimizes all the api calls the frontend makes. Currently, changing any data from any pendulum forces an update to all the backends.
  • Had a lot of difficult managing the angular offset between the frontend and the backend and in hindsight, I probably did not need to pass it to the backend.
  • I did the frontend in Vue.js since that is a framework I'm comfortable with. But I admit it had been a while and the frontend is basically all in one component.

REST Api

  • '/' - GET -- Just a heartbeat, not used
  • '/api/set_starting' - POST -- Sets all the starting positions for a pendulum
  • '/api/get_position' - GET -- Gets the positional data of the pendulum
  • '/api/start' - POST -- Starts the simulation for a pendulum
  • '/api/pause' - POST -- Pauses the simulation for a pendulum
  • '/api/reset' - POST -- Restarts the data for a pendulum, making it ready to start the simulation from where it started

breaking down tasks

  • rest intface for setup of pendulums

    • angular offset
    • mass
    • string length
    • radius (optional)
    • color (optional)

  • 5 pendulums

  • each pendulum has it's own process

  • each pendulum is told who it's neighbors are

  • one UI

  • displaying 5 pendulums

  • drag and drop pendulum start position

  • config transfered in JSON

  • UI has start, pause, stop

  • polls the 5 different pendulum instances

  • refresh rate of a few frames per second

  • each pendulum needs to watch the position of neighbors (via REST)

  • When colision is immenient, send STOP to all instances

  • STOP sent over MQTT

  • After a STOP, wait 5 seconds and RESTART

  • RESTART brings all pendulums back to starting configurations

notes

  • 5 pendulums, each with a node process

  • each process knows how to contact neighbors with config and

  • checks for immenent collisions with neigbors

  • each process connects via mqtt

  • Why not use mqtt for check on collisions?

  • lots to do, probably not going to have enough time to make it nice, just functional

  • drag and drop pendulum is odd behavior, how do I determine the anchor once the pendulum moves? angular offset might be fine

  • going to assume that the pendulums do not slow down because of a drag coeffient (I feel like that more like how continous robot platform would work)

  • selecting a pendulum and dragging it automatically stops the simulation

  • since the objects are contained within a array, we need to create custom handlers for each field to make sure the correct pendulum was updated

  • updating the string length should update the starting x,y coordinates of the pendulum

  • updating the angular offset, needs to update the x,y coordinates

  • do the anchor points move? yes, but they need to be entered

  • updating the x,y coordinates should update the string length

  • updating the radius should update the string length (no need, we will be calculating that the center of the mass is where the string is connected)

  • updating the anchorx should update the x coordinate of the pendulum (i.e. it follows, else we need to update the string length and angular offset)