Welcome to Generating Bond Graph Models

Every physical component in Bond Graphs may be modeled by a word model, which represents it simply by its name or title, and the ports that model its interaction with its environment (Figure 1.). There are two types of the ports: power ports and control or signal ports. The first one serves to model its interaction, which is characterized by transfer of the power into or outward of the component, and are represented by half-arrows, which are in a way the trademark of the Bond Graphs. The directions of the half-arrows show assumed the positive direction of the power transfer.

Control ports are borrowed from control engineering. The input port serves for the transfer of signals into the component, and output ports similarly for extraction of the signals from the component.

Figure 1. Component's Word model

To every power port there is assigned a pair of power variables: effort and flow, product of which is power transferred by the port. Similarly, to every control port there is assigned a control variable. In mechatronics efforts are typically forces, torques or voltages, and fows are linear and angular velocities, or electrical currents. Signal represents information content of a variable.

Figure 2. Bond graph

Bond lines or bonds for short are the lines drawn between the components power ports (Figure 2.). They show the ports of different components that exchange the efforts and flows, and thus there is power transfer between them. Simlarly, the lines that connect the control ports of the components describe transfer of the input or output signals to the the components over these ports. Diagrams, which show how the the components are inter-connected by the bonds or signals represents the Bond Graphs (Figure 2.). They model interactions that exist between the physical components.