Torque step

A torque step at a given time.

  • rotational
  • Modelica Standard Library
  • 1 port
  • 3 parameters
BlockTorque stepKindtorqueStepLibraryRotational

Description

Applies an offset torque that steps up by a fixed amount at the step time. Use it as a load disturbance.

Example

Rotational drivetrain A torque step drives a motor inertia through a 2:1 gear and a shaft spring into a damped load, with every rotational sensor.

Torque 1 N·mMotor 0.01 kg·m²Gear 2:1Shaft powerShaft torqueShaft 1000 N·m/radLoad 0.04 kg·m²Friction 0.1FrameMotor accelerationShaft twist rateLoad speed
In Gradara, select a Torque step block and press F1, then choose Open example. It opens as a new model in My models, ready to run.

Also in this example:Torque sensorFixed (rotational)Torsion springTorsion damperInertia (ideal)Ideal gearSpeed sensor (ideal)Acceleration sensorPower sensor (rotational)Relative speed sensor

Ports

Conserving terminals 1

  • shaftflangerotational

    Flange the torque acts on.

Parameters

  • StepstepTorque1 N·m

    Height of the step, in N·m. Negative values act as a load.

  • OffsetoffsetTorque0 N·m

    Torque before the step, in N·m.

  • Step timestartTime0.5 s

    ≥ 0

    Time of the step, in seconds.

Equations

Modelica
τ = offsetTorque + (0 for time < startTime, stepTorque afterward)
flange.tau = −τ

Implementation

Modelica Standard Library 4.1.0Modelica.Mechanics.Rotational.Sources.TorqueStep
MSL documentation

Assumptions and limitations

  • The step is instantaneous and does not depend on speed or direction.

See also

Select a block in Gradara and press F1 to open its page offline.