simscape.multibody.ExternalForceTorqueDictionary Class

Namespace: simscape.multibody

Dictionary that stores external forces and torques

Since R2025a

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Description

Use an object of the simscape.multibody.ExternalForceTorqueDictionary class to store external forces and torques to apply to a compiled multibody model. This object functions like a dictionary in that you can store the forces and torques and their corresponding frame connectors as key-value pairs. The keys are the paths to the frame connectors, appended with the letter f for force or t for torque, respectively. To construct external forces and torques, use these classes:

Class Attributes

Sealed
true
ConstructOnLoad
true
RestrictsSubclassing
true

For information on class attributes, see Class Attributes.

Creation

Description

dict = simscape.multibody.ExternalForceTorqueDictionary creates an external force and torque dictionary.

You can use dict(keys) = Values to pair an external force or torque with the path of corresponding frame connector as the key-value pair. If you assign multiple values to the same key, the last value you assign overwrites the previous values of the key.

Examples

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  1. Create an external force and torque dictionary.

    dict = simscape.multibody.ExternalForceTorqueDictionary

    dict = 

  ExternalForceTorqueDictionary with no external forces or torques.

  2. Construct a force and a torque for the frame connectors. Create a force of 5 N resolved along the x-axis of the world frame, and a torque of [2 1 0] N*m resolved about the world frame.

    force = simscape.multibody.ExternalForce(...
                     simscape.Value([5 0 0],"N"),"World");
torque = simscape.multibody.ExternalTorque(...
                     simscape.Value([2 1 0],"N*m"),"World");

  3. Use the dict dictionary to store the force and torque for the frame connectors as key-value pairs. The keys are the paths of the joint primitive appended with the letters f or t.

    dict("Bottom_arm/Tip/f") = force;
dict("Base_arm/Base/t") = torque

    dict = 

  ExternalForceTorqueDictionary with external forces and torques:

  ExternalForce:

  Frame Path          Value    Unit
  __________________  _______  ____

  "Bottom_arm/Tip/f"  [5 0 0]  N   

  ExternalTorque:

  Frame Path         Value    Unit
  _________________  _______  ____

  "Base_arm/Base/t"  [2 1 0]  N*m

    You can change the applied force and torque. For example, to replace the torque applied on Base_arm with a new torque, enter:

    torque_new = simscape.multibody.ExternalTorque(...
                     simscape.Value([5 0 0],"N*m"),"Attached");

dict("Base_arm/Base/t") = torque_new

    dict = 

  ExternalForceTorqueDictionary with external forces and torques:

  ExternalForce:

  Frame Path          Value    Unit
  __________________  _______  ____

  "Bottom_arm/Tip/f"  [5 0 0]  N   

  ExternalTorque:

  Frame Path         Value    Unit
  _________________  _______  ____

  "Base_arm/Base/t"  [5 0 0]  N*m

Version History

Introduced in R2025a

See Also

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