Application graph

The AICA application graph is a unique way of expressing complex and reactive logic for robotic control. It combines data-flow programming of continuous signals with event-driven logic and state management.

In this section, the basic elements and interactions of the application graph will be described at a high level. Mastering the graph is key to unlocking advanced programming capabilities, so be sure to continue reading further concepts and examples later in this documentation.

Nodes and edges

In graph terminology, a node is a block in the graph and an edge is a connecting line. The nodes in the AICA application graph represent components (generic computational blocks that process input data and produce output data) and hardware interfaces (drivers to externally connected devices that follow control commands from components), alongside built-in elements such as sequence or condition blocks or the start/stop nodes.

The edges connecting these nodes represent either signals (blue) or events (purple). Signals are used for continuous data exchange (e.g., control loops, signal processing, or other kinds of data flow) while event edges capture discrete logic (e.g., triggering events or representing conditional true/false states).

info

These application building blocks are described in more detail in the concepts section.

Interacting with the graph

Click and drag on the background of the graph to pan the view and zoom in and out by scrolling.

Adding elements to the graph

Application elements can be added to the graph using the right panel under the Scene tab and Add Component subtab:

At the top of the list are the "Hardware Interface", "Trigger Events Button", "Sequence" and "Condition" nodes. These are followed by a list of all available components from AICA Core and any additionally installed packages, grouped by package. Clicking on any element in the right panel will automatically add it to the graph.

The search field can be used to filter the available elements by name or description.

Managing graph elements

Nodes can be moved by clicking and dragging them. When a node is selected, a small menu provides options to rename, duplicate or delete the node. Additionally, settings for the selected node will appear in the right panel under the Scene tab and Settings subtab. This is mainly used to configure automatic state transitions such as "auto-configure" or "auto-activate" and to set parameter values. The means of editing a parameter value depend on the parameter type, with simple toggles for boolean parameters, input fields for numeric and string parameters, and an input menu accessed through the pencil edit icon for array parameters.

Depending on the application element, clicking on various parts of the node will provide additional interaction options. In particular, components and hardware interfaces have toggleable badges to configure automatic state transitions without needing to open the Settings tab, while sequences have a toggle to enable looping behavior. Sections such as Transitions, Predicates and Services will have a Show All button that can be used to expand or collapse the respective interfaces.

Deleting graph elements

To delete a node from the graph, press the small menu icon in its top right corner, then click Remove.

tip

Linux

Nodes can also be deleted by selecting them with a click and pressing the Backspace key on your keyboard.

macOS

Nodes can also be deleted by selecting them with a click and pressing the Delete key on your keyboard.

Managing graph edges

Edge connections can be made between nodes using the respective signal edge handle and event edge handle . The white side of the handle indicates the directionality of the edge; when the white side is facing away from a node, the handle is an "output" or a "source" for the edge. When the white side is facing towards the node, the handle is an "input" or a "target". Edges can only be connected between compatible handles, which generally means inputs can only be connected to outputs, and signal and event edges cannot be mixed.

Click and drag from one handle to another compatible handle to make a new edge connection. Alternatively, click once on one handle and click again on another handle to make the edge connection and avoid dragging across the graph.

Changing an event type

Event edges show the type of event they trigger as a label on the edge. To change the type of event that should be triggered, click on the event label on the edge to open a selection menu showing other available event types (for example, Load, Unload, Configure...) and click on the desired event.

Customizing edge paths

Edge paths can be manually edited for better graph layouts in any of the following ways:

• Drag an edge segment
• Click once on an edge to create a breakpoint, then drag the edge segment on either side of the breakpoint
• Click on two parts of the edge to create two breakpoints, then drag the intermediate edge segment

Note that dragging the first and last edge segments (i.e., those that connect directly to the edge handle) is not possible without first creating a breakpoint.

tip

Linux

To delete an edge, select it with a click and then press the Backspace key on your keyboard.

macOS

To delete an edge, select it with a click and then press the Delete key on your keyboard.

Runtime states

When an application is running, the graph view shows the states of each component in a banner above the node. It also indicates which signals are actively transporting data with line animations and which event edges are triggered with highlighting colors.