Bond Graph simulation (python based)

This package allows:

• to create a bond-graph model of robotics and mechatronics systems (Electrical, Mechanical, Thermal domains).
• to obtain state-space form of the system with energy variables as a state variables (with access to co-energy bariables)
• to conduct a numerical simulation of the system

Restrictions:

Curent version does work only with the 1-D systems. Examples mostly focuses on Robotics domain.

Directory is organized as folows:

• run/BondGraph2.py - the core of bondgraph models
• run/utils.py - the useful functionality to help with model creation
• demo/* - contains some scripts with the simple example to help beginers (moved from examples folder)
• dev/* - contains some scripts under development (not useful for you)

Model *(BondGraph) architecture:

• Any Port must belong to some Element (Element has a list of associated ports)
• Several Ports can belong to one Element
• Any Bond must connected only 2 Ports (Bond holds the connected ports)

Dependencies shown in the requiremens.txt

Software architecture

• class BGport
  • id
  • parent
  • type
  • name
  • position
  • value
  • direction
  • causality
  • effort
  • flow
• class BGelement
  • id
  • __type
  • __name
  • ports
  • effort
  • flow
  • stateVariable
  • inputVariable
  • parameter
  • stateEquation
  • outputEquation
• class BGbond
  • id
  • __fromPort
  • __toPort
  • effort
  • flow
  • __causalityStroke
  • __directionArrow
  • __type
• class BondGraph

  • name

  • bondsList

  • elementsList

  • portsList

  • state_vector

  • methods:

    • addElement
    • addBond
    • getBondList
    • getPortsList
    • render
      • set the appropriate positions for drawing.

BG equastions asigning sequence

1. Assign equations for 1 and 0 junction's ports (for the SE, SF, I, C and R nodes we can predefine the equastions)
2. Assign equations for the each bonds (except 1 to 0 and 0 to 1 connections)
3. Asign equations for 1 to 0 and 0 to 1 junctions

Errors and Warnings

001: Can not apply rules (input-output and causality) 002: ReExpression error: can not find the variable in the given expretion 003: Probably not defined causality during construction of the equation systems 004: Error during making the equations same form, probably some sign lost 005: Some causality lost in drawings 006: 007: Error, The bond has no effort or flow 008:

TODO list

Add example of inverted pendulum on card Add GY-TF elements (done) GUI to draw the bondgraph (without coding) API for easy interaction with model

How to contribute

If you are interested to become a contributor, please send me an email.

Useful tools to work with state-space form: https://github.com/python-control/python-control

https://python-control.readthedocs.io/en/0.9.3.post2/