General Information 🌍

This is a simple ROS demonstration of a mass-spring-damper system. In the ROS system we have two nodes: the first represents the dynamics and the second one is the controller.

System dynamics

The system's equations of motion:

$$m\ddot x = kf(t) -c\dot x -kx$$

and after laplace transformation (with zero I.C) we get a second order system:

$${X \over F} = {\omega_n^2 \over s^2 +2\omega_n\zeta s + \omega_n^2} $$

where the natural frequency $\omega_n = \sqrt{k \over m}$

You can choose the system's parameters m, k and c and choose the initial condition x0, v0 and a0 and set them in the dynamics parameters file.

The controller

You can write your own controller to try stabilize the system for a given setpoint.

the default controller is a simple PID controller with the following form:

$$f(t) = {k_pe(t) + k_i\int{e(t)dt}} + k_d {d\over dt}(e(t))$$

you can tune the controller gains, $k_p$, $k_i$, $k_d$ on the controller parameters file.

Installation 🛫

clone the repository to your local machine:

            git clone [email protected]:citros-garden/mass_spring_damper.git

open the repository in the VScode:

            cd ~/mass_spring_damper
            code .

open the repository in the container from VScode with reopen in container option.

Build 🚜

build and source the workspace:

            colcon build
            source install/local_setup.bash

Run 🚀

Recommended

Use VSCode tasks. build with build and then launch simulator with launch (default controller).

From Terminal (NOT RECOMMENDED)

you can run the free-system without controller with this launch file:

            ros2 launch dynamics dynamics.launch.py

to run the default controller:

            ros2 launch dynamics dynamics_controller.launch.py

Develop 💡

Open the project in a devcontainer with reopen in container option in VSCode, all the development environment is ready for further development.

Example from Foxglove 👀

spring_mass_example.mp4