A Coupler relationship can be defined either between a set of two joints or between a set of three joints.  The topological information required to define a Coupler is show in the figure above.

A two joint Coupler needs the following:

A three joint Coupler needs the following:

The joint can be modeled as a Single entity or as a Pair entity.

Properties of a two Joint Coupler are:

Properties of a three Joint Coupler are:

The USER function name for a Coupler entity can be COUSUB, COUXX, or COUXX2.  The properties of a Coupler can be made symmetric with the Left or the Right Coupler acting as the Master property Coupler.

Coupler Panel – Connectivity Tab – Two Joints

Coupler Panel – Connectivity Tab – Three Joints

The two joint Coupler definition needs two joints whose displacements are controlled by the Coupler ratio.

Note - The Properties tab will automatically change into the User-Defined tab.

The three joint Coupler definition needs three joints whose displacements are controlled by the Coupler ratio.

Note - The Properties tab will automatically change into the User-Defined tab.

Coupler Panel - Properties Tab – Two Joints

Coupler Panel - Properties Tab – Three Joints

Coupler Panel - User-Defined Tab

Note - Steps 15 to 20 (above) apply to both Two Joint and Three Joint Coupler types.

Coupler Panel (Pair) – Connectivity Tab

Note - The same steps as shown above can also be used to define Pair Coupler entities.

1.	Left click the Couplers panel icon on the Constraint toolbar.

The Project Browser will filter the entities and display only the Couplers in the model.

The corresponding panel is automatically displayed.

The Coupler entity can be of the following types:

All of the types of entities mentioned above can be added to the model using the MDL Statements shown below:

Single Coupler with Fixed Linear Ratios

Single Coupler with User-Defined Properties

Pair Coupler with Symmetric Linear Properties

Pair Coupler with Asymmetric Linear Properties

Pair Coupler with Asymmetric User-Defined Properties

Please refer to the *Coupler, *CouplerPair, *SetCoupler, and *SetCouplerPair topics for a detailed description of each MDL statement.

Note: To learn how to create a complete model using MDL statements, please refer to tutorial MV-1060: Introduction to MDL.

The Coupler when exported to the MotionSolve XML format is defined as a Constraint_Coupler statement.

Syntax:

<Constraint_Coupler

   id                     = "integer"

   label                  = "Coupler Entity Label"

   joint1_id              = "integer"

   freedom_1              = { "T" | "R" }

   joint2_id              = "integer"

   freedom_2              = { "T" | "R" }

[

   joint3_id              = "integer"

   freedom_3              = { "T" | "R" }

]

{

      coefficients        = "double, double [, double]"

   |

      usrsub_dll_name     = "valid_path_name"

      usrsub_param_string = "USER( [[par_1][, ...][, par_n]] )"

      usrsub_fnc_name     = "custom_fnc_name" >

   |

      script_name       = valid_path_name

      interpreter         = "PYTHON" | "MATLAB"

      usrsub_param_string = "USER( [[par_1 [, ...][,par_n]] )"

      usrsub_fnc_name        = "custom_fnc_name" >

}

</Constraint_Coupler>

In case of a three joint Coupler with linear properties the model statement will be as shown below:

<Constraint_Coupler

  id                  = "301002"

  label               = "Three Joint Coupler"

  joint1_id           = "301003"

  freedom_1           = "R"

  joint2_id           = "301004"

  freedom_2           = "R"

  joint3_id           = "301005"

  freedom_3           = "R"

  coefficients        = "1. 1. 1.5"

/>

In case of a three joint Coupler with User-defined properties, the model statement will be as shown below:

<Constraint_Coupler

  id                  = "101004"

  label               = "Coupler Pair User-left"

  joint1_id           = "101006"

  freedom_1           = "R"

  joint2_id           = "101007"

  freedom_2           = "R"

  joint3_id           = "101008"

  freedom_3           = "R"

  usrsub_param_string = "USER(301001,301003,25)"

  usrsub_dll_name     = "C:/Models/COUSUB.dll"

  usrsub_der1_name    = "COUXX"

  usrsub_der2_name    = "COUXX2"

/>

To understand the complete syntax of the Constraint_Coupler XML model statement, please refer to the MotionSolve Reference Guide Page for Constraint_Coupler.

Syntax:

mdlmodel_handle InterpretEntity new_handle keyword varname label

In case of the Coupler the statement will look as shown below:

mdlmodel_handle InterpretEntity joint Coupler c_jcoup "\"Two Joint Coupler\"" 2JOINT j_transjt j_RevJt "TRANS" "ROT" ;

Syntax: 

mdlmodel_handle InterpretSet keyword tokens;

In case of the Coupler the statement will look as shown below:

mdlmodel_handle InterpretSet SetCoupler c_jcoup -0.9;