Build a Model and Visualize Results

This example shows how to create a simple model that generates a plotted output. Simscape Driveline blocks belong to either the mechanical rotational domain or the mechanical translational domain. You use Simscape Driveline blocks to create the model, parameterize the blocks to change the model functionality, and then visualize the results. You then use a sensor block to visualize physical data.

This example uses blocks in the rotational mechanical domain, but you can apply these principles from this example to create a translational system model. You can start with simple or ideal inputs and physics to validate that a block behaves as expected before adding it to a more complex model. The blocks perform equations on the system variables to represent the physics of that block. To learn more about the block equations and parameters, see the reference for the block.

Build a Mechanical Rotational Model

You can open a Simulink canvas with block and links that are helpful for modeling in the mechanical rotational domain. In the MATLAB window, click the Simulink button to open the Simulink Start Page. Under the New tab, navigate to Simscape and click the Create Model button for Mechanical Rotational.

The canvas includes a Mechanical Rotational Reference block connected to the Solver Configuration block. Double-click the canvas and add these Simscape and Simscape Driveline blocks to the model:

• Ideal Angular Velocity Source

• PS Step

• Simple Gear

• Rotational Free End

Follow these steps to build the model:

1. Connect port C of the Ideal Angular Velocity Source block to the Mechanical Rotational Reference block.

2. Connect port R of the Ideal Angular Velocity Source block to port B of the Simple Gear block.

3. Connect the PS Step block to port S of the Ideal Angular Velocity Source. Then double-click the PS Step block, and set Final value to 10.

4. Connect port F of the Simple Gear block to the Rotational Free End block.

5. Delete the Simulink-PS Converter block. You can leave the PS-Simulink block and the Scope block disconnected from the model until later.

You can rotate blocks on the canvas by right-hand clicking the block and selecting Format > Rotate Clockwise, or by pressing CTRL+R. To learn more about interacting with the model canvas, see Configure Model Layout. Save the model as myModel.

The model is ideal with no friction, mass, or dynamic forces such that the Ideal Angular Velocity Source block requires no torque to bring the system to steady state. The mechanical translational and mechanical rotational domains each have their own reference blocks. In this model, the Mechanical Rotational Reference block defines a point of zero motion and orientation. Simscape defines the connected blocks relative to this reference frame.

The Simple Gear block has a default follower to base ratio of 2:1. To define the reduction ratio parameter as 3, set Follower (F) to base (B) teeth ratio (NF/NB) to 3.

Use a Sensor Block to Output Data to a Scope Block

You can use sensor blocks to track one or more model variables, and you can visualize the sensor data using a Scope block. Sensor blocks are ideal and do not physically impact your model. The list contains translational and rotational sensor blocks:

• Translational Power Sensor

• Rotational Power Sensor

• Ideal Translational Motion Sensor

• Ideal Rotational Motion Sensor

• Ideal Force Sensor

• Ideal Torque Sensor

You can find these blocks in the Simscape Foundation Library.

To see the output shaft speed of the Simple Gear block, attach an Ideal Rotational Motion Sensor block and a Scope block to the model. Because the sensor block outputs a physical signal, you must use a PS-Simulink Converter block between the Scope block and port W of the Ideal Rotational Motion Sensor block. Open the block dialog box for the Ideal Rotational Motion Sensor block, and set Measurement reference to Absolute. Branch the signal between the Simple Gear block and the Rotational Free End block and connect it to port R of the sensor.

Run the model from the Scope block to generate the results.

The shaft reaches a constant rotational velocity after the step input. The speed is one third the magnitude of the input. Recall that the result requires no torque to start because the system has no mass or friction. Note that port F rotates in the opposite direction of port B when you set Output shaft rotates to In opposite direction to input shaft.

To open the completed model, enter:

openExample('sdl/SimpleRotationalMechanicalSystemExample')