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
• make a 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/BondGraph.py - the core of bondgraph models
• run/utils.py - the useful functionality to help with model creation
• examples/* - contains some scripts with the simple example to help beginers
• dev/* - contains some scripts under development

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 elements 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/