In this example, create an architecture model of a mobile robot that consists of sensors, motion, and a planning algorithm. Define the interfaces and link the requirements.
Capture the construction of a robot arm using System Composer™. The robot arm consists of the components shown in this preliminary sketch.
In the MATLAB® Command Window, type
The Simulink® Start Page opens to System Composer.
Click Architecture Model.
A composition editor window opens with a new architecture model. You can identify an architecture model by the badge in the lower left corner and the component palette on the left side.
Double-click the architecture model header and change untitled to Robot. The name of the model generally reflects the system whose architecture you are building.
Save the model.
Click and drag a Component from the left-side palette.
Rename the component to
Trajectory Planning and
You can add a port to a component on any side and the port can have either an input or output direction. To create a port, pause the mouse cursor over a component side. Click and release the mouse button to view direction options. Select either or to select the direction. Rename the port using a name that is representative of the information that flows through that port.
Create an output port on the bottom side of the Sensors component. Rename it
Click and drag a line from the
SensorData output port to the
Motion component. When you see an input port created at the
component side, release the mouse button. By default, this new port has the same name
as the source port.
Hover on the corner of the
SensorData line until you see the
branch icon.. Right-click and drag a branch line to the
Trajectory Planning component.
Complete connections as shown in the following figure.
The root level of the architecture model can also have ports that describe the interaction of the system with its environment. In this example, the target position for the robot is provided by a computer external to the robot itself. Represent this relationship with an input port.
Click the left edge of the architecture model and type the port name
Connect an architecture port to a component by dragging a line from the
TargetPosition input port to the
Planning component. Connections to or from an architecture port appear as
Specify the data flow between components by configuring the data interface with data types, units, dimensions, and other attributes. An interface can be as simple as sending an integer value, but it can also be a set of numbers, an enumeration, a combination of numbers and strings, or a bundle of other predefined interfaces.
Consider the interface between the
Sensors and the
Motion components. The sensor data consists of:
Position data from two motors
Obstacle proximity data from two sensors
A time stamp to capture the freshness of the data
The data has these specifications.
|position1 for motor 1||double||degrees|
|position2 for motor 2||double||degrees|
|distance1 for sensor 1||double||meters|
|direction1 for sensor 1||double||degrees|
|distance2 for sensor 2||double||meters|
|direction2 sensor 2||double||degrees|
In the Modeling tab, select Interface Editor.
Click the button to add an interface and name it
The interface is named and defined separately from a component port and then assigned to a port.
SensorData output port on the
Sensors component. In the Interface Editor, right-click
sensordata and select Assign to Selected
If you click
sensordata again, the three
SensorData ports are highlighted, indicating the ports are
associated with that interface.
Add an element to the selected interface. Click the button to add an element and name it
Continue adding elements to the interface as specified by clicking the add element button.
Edit the properties of an interface element using the Property Inspector.
Right-click an any element and select
Inspect Properties. The
Property Inspector opens above the Interface Editor.
Click each interface element and add units as shown in the specification. Click the
drop-down next to the button to save the interface to a data dictionary. A
data dictionary allows you to collectively manage and share a set of interfaces among
interrelated models. For instance, later in the design, if you choose to model the
external computer as a separate architecture model, then this model and the Robot model
can share the same data dictionary. Here it is saved as
Each component can have its own architecture. Double-click a component to decompose it into its subcomponents.
Trajectory Planning component. The title or
Model Browser indicates the position of the component in the
This component first uses the motor position data that is part of the
sensordata interface to compute the ideal position and velocity
command. It then processes the obstacle distance information in the same interface to
condition this motion command, according to some safety rules.
Motion Control and
Safety Rules components
as part of the
Trajectory Planning architecture.
TargetPosition port to the
Control component. Add a
Command output port to
Motion Control, and then drag a line to the
Rules component. Drag lines from
SensorData port to
Motion Control and
If you have a component that represents a single functional unit that does not need further architectural decomposition, you can define either its intended or detailed behavior model in Simulink.
Motion Control component and select
Create Simulink Behavior.
Type the name for a new Simulink model. Select either a blank Simulink template (default) or a template that you created and click OK. For more information about creating your own Simulink templates, see Create Template from Model.
This creates a new Simulink model in the current directory, converts the component to a reference component (one that refers to another model stored as a separate artifact), and adds a Simulink model badge with the name of the referenced model on the component. The Simulink behavior model is preconfigured with the ports from the component in the architecture model. You can now use Simulink to elaborate the behavior model of the Motion Control.
Motion Control. Add a Sum block to
TargetPosition, and add a
Gain block before connecting to the output
to represent a simple proportional controller.
You can also link to an existing Simulink behavior model from a System Composer component if one is already available from a previous design.
Right-click the component and select
Enter the name of a Simulink model.
Any subcomponents and ports that are present in the component are deleted when the component links to a Simulink model. The component then is created with ports that are the same as those described in the Simulink model.