Using Design Tables for Law Excitations

You can assign a design table to law excitations. A design table assigns discrete distance or angle values to each time increment in a kinematics simulation. These distance or angle values are assigned to a command at each increment, and the configuration of the mechanism is recalculated accordingly.

Related Topics
Creating a Law Excitation
Interpolation of Time Increments

To assign a design table to an excitation, you must first create an excitation and associate it with a command (see Creating a Law Excitation); you can leave the Formula field empty when you define the initial excitation. Defining the initial excitation creates time and command parameters that can be referenced in the design table. You may need to create multiple excitations if the design table will include multiple commands.

To define a design table, click in the Knowledge toolbar. The design table must associate the time parameters in an excitation with a distance or angle value for the associated command. If you use a design table to drive multiple commands from multiple excitations, you can include either a single time parameter or multiple time parameters in the design table:

  • If you include only a single time parameter in the design table, all command values in the table are defined in relation to this time parameter. This single time parameter can be associated with any of the commands in the scenario.

    Excitation.1\Time(sec) 0 1 2 …
    Excitation.1\Length(mm) 5 7 10 …
    Excitation.2\Length(mm) 3 0 3 …
    Excitation.3\Angle(deg) 45 50 55 …

  • If you include multiple time parameters in the design table, you must include the time parameters associated with every command that appears in the table. Each command value is defined in relation to its associated time parameter.

    Excitation.1\Time(sec) 0 1 2 …
    Excitation.1\Length(mm) 5 7 10 …
    Excitation.2\Time(sec) 0 3 6 …
    Excitation.2\Length(mm) 3 8 10 …
    Excitation.3\Time(sec) 0.5 4 5.5 …
    Excitation.3\Angle(deg) 45 70 30 …

If all of the commands in a design table are independent (the value of one command has no impact on the value of any other command), a value must be assigned to each command in each time increment—no empty cells can appear in the design table.

If the commands are interdependent (the value of one command can be inferred from the value of another command), one of the commands should be considered a "master" command. Values are assigned only to the master command, and the cells corresponding to the other commands should be left empty; values for the other commands are calculated during the simulation. The designated master command can change from increment to increment, but only a single interdependent command should be assigned a value in any given increment. When you directly assign command values to multiple interdependent commands, you will not be able to simulate the mechanism if the command values are not compatible with the interdependency rules.

For more information about defining design tables, see the Infrastructure User's Guide: Using DesignTables..