Pendulum Post-Processing Pipeline for MBDyn

This repository demonstrates a complete, headless post-processing pipeline for MBDyn (MultiBody Dynamics) simulations using Python.

The project focuses on converting raw MBDyn simulation output (.mov files) into meaningful physical quantities and visualizations, including plots and animated videos.

Currently, the pipeline is demonstrated using a simple pendulum system.

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Motivation

MBDyn produces accurate physical simulation data, but its raw output is not directly suitable for analysis or visualization.

The objective of this project is to:

• Interpret raw MBDyn output data
• Extract physically meaningful quantities (e.g., angular displacement)
• Validate simulation results through plots and animations
• Provide a reusable, automated post-processing workflow

This work is intended as a preparatory contribution toward Google Summer of Code with the MBDyn organization.

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Features

• Parses MBDyn .mov output files
• Converts raw nodal coordinate data into NumPy arrays
• Computes pendulum angular displacement (θ)
• Plots θ vs time
• Generates MP4 animations using Matplotlib (headless, no GUI required)
• Optional FreeCAD-based 3D visualization

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Pipeline Overview

MBDyn → .mov → Python parsing → NumPy arrays → Plots → MP4 animation

Pipeline Description

1. MBDyn Simulation
   MBDyn generates raw output (.mov) containing the coordinates of structural nodes (e.g., hinge point and pendulum bob).

2. Data Processing
   Python scripts extract nodal coordinates and compute the angular displacement θ of the pendulum using geometric relations.

3. Analysis & Visualization

   • Angular displacement is plotted as θ vs time.
   • A headless Matplotlib animation is generated and exported as an MP4 file.

4. Optional FreeCAD Visualization
   A FreeCAD-based script can be used to visualize motion in 3D by updating object positions frame-by-frame using MBDyn output data.

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Requirements

• Python 3.10+
• NumPy
• Matplotlib
• FFmpeg (for video generation)

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Usage

1. Parse MBDyn output:

python scripts/parse_mbdyn_output.py