Inertia (AB)

Ideal inertia in angle-based rotational systems

Since R2026a

expand all in page
  • Inertia (AB) block

Libraries:
Simscape / Foundation Library / Rotational / Elements

Description

The Inertia (AB) block represents an ideal inertia in angle-based rotational systems. The block uses the equation

t=I⋅ω˙

where:

  • t is torque of the rotational network acting on the inertia.

  • I is inertia.

  • ω is inertia angular velocity.

B and F are angle-based rotational conserving ports. The ports are rigidly connected to each other. Positive torque accelerates the inertia in the positive direction.

Use the Visible ports parameter to select whether to expose both ports or only one port, B or F, depending on your diagram layout. Because the two ports are rigidly connected to each other, the difference between the one-port and two-port variants is purely graphical.

Variables

To set the priority and initial target values for the block variables prior to simulation, use the Initial Targets section in the block dialog box or Property Inspector. For more information, see Set Priority and Initial Target for Block Variables.

Nominal values provide a way to specify the expected magnitude of a variable in a model. Using system scaling based on nominal values increases the simulation robustness. Nominal values can come from different sources, one of which is the Nominal Values section in the block dialog box or Property Inspector. For more information, see Modify Nominal Values for a Block Variable.

Examples

Interpreting Angle in the Angle-Based Rotational Domain

Interpreting Angle in the Angle-Based Rotational Domain

Set up and interpret angles in angle-based rotational models. It provides background information to explain the underlying concepts. The angle-based rotational domain tracks angle, θ, and rotational velocity, ω, at every node. Use angle-based rotational blocks to model rotational systems where knowing multiple component angles is important.

Interpreting Torque in the Angle-Based Rotational Domain

Interpreting Torque in the Angle-Based Rotational Domain

Describes how to interpret torques in a Simscape™ angle-based rotational network. It outlines the key concepts for understanding the signs of logged torques. It examines rotational spring systems driven by torque sources at different ends, as well as a rotational system of inertias, to illustrate the torque behavior.

Ports

Conserving

expand all

Angle-based rotational conserving port that represents the base connection.

Dependencies

To enable this port, set the Visible ports parameter to either B and F or B.

Angle-based rotational conserving port that represents the follower connection. This port is rigidly connected to the base port.

Dependencies

To enable this port, set the Visible ports parameter to either B and F or F.

Parameters

expand all

Main

Inertia value. The inertia is constant during simulation.

Ports

To improve block diagram readability, you can specify whether to expose both ports or only one port, B or F. Because the two ports are rigidly connected to each other, the difference between the one-port and two-port variants is purely graphical. Select the ports visible on the block icon:

  • B and F — Expose both ports, B and F.

  • B — Expose only port B.

  • F — Expose only port F.

Extended Capabilities

expand all

C/C++ Code Generation
Generate C and C++ code using Simulink® Coder™.

Version History

Introduced in R2026a

See Also

|