simscape.multibody.JointActuationDictionary Class

Namespace: simscape.multibody

Dictionary to store joint primitive actuations

Since R2024a

Description

Use an object of the simscape.multibody.JointActuationDictionary class to store joint actuations to apply to a compiled multibody model. The object is a dictionary in that you can store joint actuations and their corresponding joint primitives as key-value pairs. The keys are the paths of the joint primitive with the letter f or t, which indicates force or torque, respectively. The values are the actuation force or torque created by using these classes:

• simscape.multibody.PrismaticPrimitiveActuationForce

• simscape.multibody.RevolutePrimitiveActuationTorque

• simscape.multibody.SphericalPrimitiveActuationTorque

Class Attributes

Sealed	true
ConstructOnLoad	true
RestrictsSubclassing	true

For information on class attributes, see Class Attributes.

Creation

Description

dict = simscape.multibody.JointActuationDictionary creates a default joint actuation dictionary to store joint primitive actuations and the paths of the corresponding joint primitives.

Examples

Pair Actuations with Joint Primitives

1. Create a joint actuation dictionary to store joint actuations and their corresponding joint primitives.

   dict = simscape.multibody.JointActuationDictionary
   

   dict = 
   
     JointActuationDictionary with no actuations.

2. Construct actuations for the desired joint primitives. Create a force of 5 N for a prismatic joint primitive, a torque of 10 N*m for the revolute joint primitive, and a torque of [3 4 5] N*m for a spherical joint primitive.

   force = simscape.multibody.PrismaticPrimitiveActuationForce(...
                        simscape.Value(5,"N"));
   torque_r = simscape.multibody.RevolutePrimitiveActuationTorque(...
                        simscape.Value(10,"N*m"));
   torque_s = simscape.multibody.SphericalPrimitiveActuationTorque(...
                        simscape.Value([3 4 5],"N*m"));
   

3. Use the dict dictionary to store the created actuations with desired joint primitive as key-value pairs. The keys are the paths of the joint primitive with a letter f or t.

   dict("Pg/Pz/f") = force;
   dict("Ri/Rz/t") = torque_r;
   dict("Ro/S/t") = torque_s
   

   dict = 
   
     JointActuationDictionary with actuations:
   
     PrismaticPrimitiveActuationForce:
   
     Primitive Path  Value  Unit
     ______________  _____  ____
   
     "Pg/Pz/f"       5      N   
   
     SphericalPrimitiveActuationTorque:
   
     Primitive Path  Value    Unit
     ______________  _______  ____
   
     "Ro/S/t"        [3 4 5]  N*m 
   
     RevolutePrimitiveActuationTorque:
   
     Primitive Path  Value  Unit
     ______________  _____  ____
   
     "Ri/Rz/t"       10     N*m 

   After you create a dictionary, you can change the actuation for a joint primitive path. For example, to replace the actuation torque for the Ri joint primitive with a new torque, enter:

   torque_r_new = simscape.multibody.RevolutePrimitiveActuationTorque(...
                        simscape.Value(-5,"N*m"));
   dict("Ri/Rz/t") = torque_r_new
   

   dict = 
   
     JointActuationDictionary with actuations:
   
     RevolutePrimitiveActuationTorque:
   
     Primitive Path  Value  Unit
     ______________  _____  ____
   
     "Ri/Rz/t"       -5     N*m 
   
     SphericalPrimitiveActuationTorque:
   
     Primitive Path  Value    Unit
     ______________  _______  ____
   
     "Ro/S/t"        [3 4 5]  N*m 
   
     PrismaticPrimitiveActuationForce:
   
     Primitive Path  Value  Unit
     ______________  _____  ____
   
     "Pg/Pz/f"       5      N   

More About

Usage

Use simscape.multibody.JointActuationDictionary to create the dictionary, dict. Then you can use dict to pair joints actuations with the joint primitives by using this syntax:

dict(keys) = Values pairs a joint actuation force or torque with the path of desired joint primitive as the key-value pair. If multiple values are assigned to the same key, then only the last of those values is assigned. New assignments to an existing key overwrite the value for that entry.

Version History

Introduced in R2024a