Computational Kinematics and Dynamics of Mechanical Systems

This a coursework in 2021 when I was an undergraduate student at Shanghai Jiao Tong University. It implements two dimensional computation of kinematics and dynamics of mechanical systems, including two-link mechanism, crank-slider mechanism, and others. I implemented some matrix calculations and classes of constraints in C++ myself.

Requirements

C++ is used for computation and Python is used for visualization. I used Visual Studio 2019 and Pycharm 2020.2 as IDEs (so you can find .sln files in the repository). For python, I used Python 3.7.6 with an Anaconda environment (But I cannot find exact versions of packages I used since it was five years ago).

Some code files may be encoded by GB2312 because of some Chinese contents.

Usage

I assume that users of the repository have basic knowledge about computational kinematics/dynamics so are familiar with constraint equations and solutions.

For kinematics

One can find two examples (INP0 and INP2 in KinematicsExer) of questions, their descriptions of constraints, detailed velocity and accelaration equations, flow chart, and results in Kinematics/Report.docx.

1. Use create_INPfile.py to generate a input file (such as INP*.txt in the repository) for rigid bodies and constraints. See the .docx file, INP0.txt, and INP2.txt for descriptions of constraints.
2. Use create_bodyshape.py to generate a file for geometries of objects (such as INP*_shape.txt in the repository).
3. Run plot.py to select the input file and geometry file.
4. plot.py then calls Kinematics.exe complied from KinematicsC++ that generates outputs, and plot the outputs, including positions, velocities, and accelarations of objects, charts, and a mp4 file.

No space is allowed in filepaths.

Flow chart of kinematics

For dynamics

Two examples (INP4 and INP5 in DynamicsExer) are reported in Dynamics/Report.docx containing descriptions of equations and results.

1. Write an input file (such as INP*.txt in the repository) for rigid bodies, constraints, and forces. See Dynamics/Report.docx, INP4.txt, and INP5.txt for examples.

2. Use create_bodyshape.py to generate a file for geometries of objects (such as INP*_shape.txt in the repository).

3. Run main.py to select the input file and geometry file.

4. main.py then calls Dynamics.exe complied from DynamicsC++ that generates outputs, and plot the outputs, including positions, velocities, accelerations, and Lagrangian multipliers of objects, charts, and a mp4 file.

Flow chart of dynamics

Examples

Kinematics

INP1_output.mp4

INP2_output.mp4

Dynamics

INP2_output.mp4

(With a spring)

INP3_output.mp4