Inventor representations manage views, component visibility, component position and many other things. As saved configurations, you can restore them and their settings at any time.
You use view representations to manage view-related information. They aid the design process by preparing the model for presentation and improving performance. You can read more here.
Positional representations capture snapshots of kinematic assemblies. Use these snapshots to review motion and check component positions. You can apply the representations to both assemblies and drawing views.
Above, for example, is a hydraulic cylinder. You can flex the assembly into three positions using positional representations by creating and managing view representations in the Inventor Model browser.
To create a new representation, right-click the Position browser node and select New. Inventor inserts the new entry with a default name.
With the creation of the first representation, Inventor also adds the primary representation. Each assembly has this master representation, which represents the default state. This is also where modeling operations take place. You cannot edit the primary representation, but you need it to be active to save the assembly.
Double-click a representation to activate it and then click twice slowly to rename it. All other options are available via the right-click menu. Use Copy to duplicate the representation and make it active. Use Delete to remove the representation.
The active state is the one with the checkmark. Its name also appears on the Position browser node.
Creating a new positional representation allows you to change component positions and constraint settings without affecting the original representation. Here is a quick summary of the process:
- Create a positional representation.
- Modify (override) values for the positional representation.
- Save the changes in the assembly.
There are many operations that are not allowed when you are working with the nonprimary positional representation. For example, you cannot add, delete or reorder components. You can, however, perform the following operations related to representations:
- Change component placement by relationship value or move the component.
- Modify parameters.
- Change the flexibility status of subassemblies.
- Turn visibility on and off.
Pro Tip: When a positional representation is active, you cannot save the changes to an assembly. To save changes, activate the primary representation in the top-level assembly.
Using positional representations
When opening an assembly, you can specify the positional representation. By default, Inventor uses the last active representation.
You can also insert subassemblies using a selected representation, as opposed to setting it after you create them.
Instances of a subassembly do not all need to be the same representation. From the browser and the Representation dialog (right-click menu), you can set the desired representation for the instance.
Flexibility
Flexibility is often an important feature with positional representations.
When placing a subassembly into an assembly, Inventor treats it as a single object. You cannot move the assembly’s individual components. By making the subassembly flexible, you expose its degrees of freedom and allow movement of its parts.
Flexibility only reveals the degrees of freedom available in the assembly. If it is not flexing as desired, open the assembly and review its relationships. The degrees of freedom feature is useful for this.
For example, a hydraulic cylinder must be free to move along its axis to properly represent its kinematic assembly motion. By making it flexible, you can free movement of the rod along its length.
To enable flexibility, right-click the instance in the browser and select Flexible from the menu. The browser icon changes to show that Flexible is enabled.
Pro Tip: A component cannot be both flexible and adaptive. The advantage to flexibility is that not all instances of the component must be flexible. You can also manage flexibility with positional representations, which you cannot do with the adaptive option.
Overrides
By applying overrides, you alter the component, putting it into a state that is different from the primary. With a positional representation active, these in-process adjustments apply only to that specific representation.
You apply overrides from the right-click menu. The component or object appears in bold with a suffix that indicates an override is applied.
For flexibility, right-click on the subassembly and select Flexible (Override) from the menu. This makes the assembly flexible but only affects the active representation. This means making the subassembly flexible in only select representations but not all.
The same occurs when making a component Grounded.
You can nest representations. This means the parent assembly’s positional representation can set a positional representation for the subassembly.
Right-click on the component and select Override. This launches the Override dialog. From the Representation tab, enable Override for positional representations and select the desired representation.
From the Override dialog, you can also override component Grounding status, Relationship Suppression and Values, and Positional Offset values. Just select the Override checkbox and select the desired value.
Use the Remove Override option to quickly remove multiple overrides from the component.
Instead of using the dialog, you can also override constraints and relationships by right-clicking the relationship and selecting Modify (Override), or by double-clicking it. When the Override Object dialog box appears, adjust the value to the desired position. Or if an override value is already applied, single-click on the relationship and adjust the value in the text box.
Going back to the cylinder example, to create the various positions, a Mate constraint is overridden by adjusting the offset between the rod and cylinder housing. In addition to the open, closed and mid-stroke positions, a Free representation is created. In this representation, the constraint is suppressed and the assembly set is flexible. This allows the cylinder to be dynamically dragged and adjusted through its range of motion.
Pro Tip: Be careful with Model States when you are working with positional representations as you do not want to suppress components constrained by the constraints you are overriding. This will cause you nothing but grief and headaches.
Representations browser
The Representations browser is a view focused on positional representations. It lists the representations with the overrides applied to each representation.
From it, you can activate, create new, copy and delete representations. You can also find, adjust and remove overrides.
Use Verify Positional Representations to recompute the model’s positional representations and ensure they are valid (have no errors).
As your positional representations become more complex with the number of overrides, you may find it easier to manage the values using a spreadsheet because a spreadsheet allows you to use formulas to calculate values and change multiple cells at a time.
Inventor presents only the values overridden in the positional representations in this tabular format. A row is created for each representation. The column headers identify the value set, for example, its flexible status or the constraint name.
Pro Tip: When making changes to the spreadsheet, do not add, remove, reorder or edit the column headers. Do not remove, reorder or rename rows. If a value is missing, close the spreadsheet and add the representation or apply the override within Inventor, then relaunch the spreadsheet.
Drawing views
When creating drawing views, you can select the desired positional representation. You can also apply different representations to the views in your drawing to aid in documentation.
Create overlay views to overlay a positional representation over an existing view. You can apply multiple overlays to highlight the assembly in multiple positions within a single view.
You can add dimensions and other annotations between the components in the overlays to show how much the component has moved.
Pro Tip: Consider using View Representations to show only the components that are changing positions. This creates less cluttered views.