Rotational Inertia

Ideal mechanical rotational inertia

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Libraries:
Powertrain Blockset / Drivetrain / Couplings
Vehicle Dynamics Blockset / Powertrain / Drivetrain / Couplings

Description

The Rotational Inertia block implements an ideal mechanical rotational inertia.

Power Accounting

For the power accounting, the block implements these equations.

Bus Signal			Description	Variable	Equations
PwrInfo	PwrTrnsfrd — Power transferred between blocks Positive signals indicate flow into block Negative signals indicate flow out of block	PwrR	Mechanical power from base shaft	PTR	$P_{TR}= T_R\omega$
		PwrC	Mechanical power from follower shaft	PTC	$$P_{TC}= T_C\omega$$
	PwrNotTrnsfrd — Power crossing the block boundary, but not transferred Positive signals indicate an input Negative signals indicate a loss	PwrDampLoss	Power loss due to damping	Pd	$P_d=-b{\left|\omega \right|}^2$
	PwrStored — Stored energy rate of change Positive signals indicate an increase Negative signals indicate a decrease	PwrStoredShft	Rate change of stored internal torsional energy	Ps	$P_s=\omega \dot{\omega }J$

The equations use these variables.

TR	Input torque
TC	Output torque
ω	Driveshaft angular velocity
J	Rotational inertia
b	Rotational viscous damping
Pd	Power loss due to damping
Ps	Rate change of stored internal torsional energy

Ports

Input

RTrq — Input torque

scalar

Applied input driveshaft torque, T_R, in N·m.

Dependencies

To enable this port, for Port Configuration, select Simulink.

CTrq — Output torque

scalar

Load driveshaft torque, T_C, in N·m.

Dependencies

To enable this port, for Port Configuration, select Simulink.

R — Angular velocity and torque

two-way connector port

Angular velocity in rad/s. Torque is in N·m.

Dependencies

To enable this port, for Port Configuration, select Two-way connection.

Inertia — Input

scalar

Rotational inertia, in kg·m^2.

Dependencies

To create the Inertia port, select External inertia input.

Output

Info — Bus signal

bus

Bus signal containing these block calculations.

Signal			Description	Variable	Units
Trq	R		Applied input driveshaft torque	TR	N·m
	C		Output driveshaft torque	TC	N·m
	Damp		Damping torque	Td=bω	N·m
Spd			Angular driveshaft speed	ω	rad/s
PwrInfo	PwrTrnsfrd	PwrR	Mechanical power from base shaft	PTR	W
		PwrC	Mechanical power from follower shaft	PTC	W
	PwrNotTrnsfrd	PwrDampLoss	Power loss due to damping	Pd	W
	PwrStored	PwrStoredShft	Rate change of stored internal torsional energy	Ps	W

Dependencies

To enable this port, select Output Info bus.

Spd — Driveshaft speed

scalar

Angular driveshaft speed, ω, in rad/s.

Dependencies

To enable this port, for Port Configuration, select Simulink.

C — Angular velocity and torque

two-way connector port

Angular velocity in rad/s. Torque is in N·m.

Dependencies

To enable this port, for Port Configuration, select Two-way connection.

Parameters

Block Options

Port Configuration — Specify configuration

Simulink (default) | Two-way connection

Specify the port configuration.

Dependencies

Specifying Simulink creates these ports:

• RTrq

• CTrq

• Spd

Specifying Two-way connection creates these ports:

• R

• C

Output Info bus — Selection

off (default) | on

Select to create the Info output port.

External inertia input — Input rotational inertia

off (default) | on

Dependencies

To create the Inertia port, select External inertia input.

Parameters

Rotational inertia, J — Inertia

.01 (default) | scalar

Rotational inertia, in kg·m^2.

Dependencies

To enable this parameter, clear Input rotational inertia.

Torsional damping, b — Damping

.001 (default) | scalar

Torsional damping, in N·m· s/rad.

Initial velocity, omega_o — Angular

0 (default) | scalar

Initial angular velocity, in rad/s.

Extended Capabilities

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

Version History

Introduced in R2017a