Rotational Inerter (AB)
Libraries:
Simscape /
Foundation Library /
Rotational /
Elements
Description
The Rotational Inerter (AB) block represents a device that has torque proportional to the rate of change of the relative angular velocity across the ports. It is essentially a two-port inertia that works on the velocity difference between the ports, not the absolute velocity. The block uses these equations
where:
t is torque transmitted through the inerter.
Inertance is the proportionality coefficient between the torque and the rate of change of the relative angular velocity across the ports.
ωRel is the relative angular velocity between ports.
ωB and ωF are the absolute angular velocities of ports B and F, respectively.
θRel is the relative angle between ports.
θB and θF are the absolute angles of ports B and F, respectively.
B and F are angle-based rotational conserving ports. For positive relative angle, port F has a more positive angle than port B. The inerter torque acts from port B on port F. Positive torque drives port F in the positive direction.
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
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
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
Parameters
Extended Capabilities
Version History
Introduced in R2026a
