Welcome to Control Signal Elements

The Block digrams are well known from Control Engineering. They consists of control signal components, also known as input-output components, which are connected by the signals. They differ from elementary components because their outport signals are defined by the values of the input ports signals. Such relationship is known as explicit. On the other hand in Bond Graphs it is generally not known whether the power port efforts or flows are the inputs or outputs. In other word, whether we know the port effort and trying to evaluate the corresponding flow, or vice versa. Thus, their consitutive relations are treated as implicit. The control components are added to Bond Graphs to enhance their modeling capabilities. The basic control components we use are shown in the table below:

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Type Symbol Constitutive Releations Note
Input Generator IN c = fun(t, par) t - time, p - parameters
Summator SUM cout = ±cin1 ±cin2 ... ±cinN The additing (+) or subtraction (-) are set when definining the summator.
Function FUN cout = fun(t, cin1,..., cinN, par) par - parameters
Integrator INTG cout = ∫cin∙dt Set the initial condition.
Differenciator D/DT cout = d cin/ dt no parameters
Node NODE The output signnals are equal to the input one. the branching node
Display DISPLAY dispays the input signals
IPC IPC the named pipe

We often insert a control-out port into 1- or 0- junction to extract the junction variable,an effort or a flow. By connecting this port by a signal to the input of a function on its output we obtain the processed value of the junction variable. The processing law is defined by the function's constitutive relation. Similarly, we find the position of a point in a body. We pick the velocity of the corresponding 1-junction and connect it to the input of the integrator, and using the suitable initial condition, we get the position. The Display components, which mimic a x-y plotter, displays x-t or x-y plots of the signals connected to its ports during the simulation. We may set as many display components as we want in the Bond Graph model.

A very useful new component that is introduced is Inter Process Comunication or IPC for short. This component transmit the signals connected to its input port to another process (a server). It also returns the signals generated by the server at output port. The IPC component is implemented in BondSim as a named pipe.

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