Get Started

To start a modeling session we define first a corresponding project. This can be a new one or an already existing project. The Project menu contains commands for operations on the projects. To illustrate the general modeling technique consider a simple mechanical systems consisting of a body of mass m, which is connected by a spring of stiffness k and damper with linear friction constant b, to a vertical wall (see below). The body can move along the horizontal floor under the action of an external force F.

Simple mechanical system 
Get StartedWe start by creating a new modeling project and select New command in Project menu, or click the New Project toolbar button. The Create New Project dialog opens as shown below. It contains a text box, which serves to define a new project name, and the list box showing already existing projects. We have to type a name that is different of already existing project names, e.g. “Body Spring Damper Problem” (without the quotation marks of course) and click OK button. We can reject the operation by clicking Cancel button.
Create New Project dialog
Get Started

The dialogue closes and a new empty project document appears in the central part of the frame. Its title is PROJECT: Body Spring Damper Problem. It is the project level document, and serves to define the basic (system) level model. The document window contains a rectangle that defines the document working area in which the model is created. It is bounded by a grey strip, which limits the area where the components may be placed.

The screen with opened a new project

Get StartedThe menu now changes and shows the commands that can be applied to the project. If we expand the Model Structure (by clicking on ‘+’ box on its left) it shows only the project entry: Body Spring Damper Problem (see figure below). The tools that are used to create the component model are in the Editing box on the right. It contains several branches. We expand the branches we use most during Bond Graph model development: Ports, Bond Graph Components, Font Size and Text Orientation.

Model Structure and Editing Tools branches expanded
Get Started

The Bond Graph Component branch contains the Bond Graph components tools. The first one, the Component Model, is used to create the general component models in the form of the word models. The others are used for creating of the elementary components, which model the basic physical processes in the project or its components. The models are created by dragging the tool into the document window and dropping it there, but not too close to the grey border. 

The Ports branch contains the tools for inserting ports into the component boundary. The Power-in and Power-out port tools serve to create the power ports. They are created as half-arrows directed into and out of the component, thus indicating the positive sense of power transfer. Control-in and Control-out tools are used for the control ports, i.e. the ports that transfer the signals into or out of the components. The other two ports are more specific and are used when modeling the discrete-time processes. To insert a port its tool is dragged into the document window and dropped at the component boundary.

To edit the component titles default font are used (Arial). But, the different font sizes can be chosen. There are four sizes to choose from: Normal, Small, Medium and Large. The component titles can run horizontally from left to right, or vertically from down to up. Default text direction is the horizontal. However, we may change this by selecting Horizontal or Vertical type in Text Orientation branch of Edit Box.