D3.1 OnShape Robot Organization

Contents

• Top-Down Modeling
• Multiple Documents and Versioning
• The importance of the Origin
• Primary Assembly
• Primary Sketches
• Space Allocation Volumes/Shapes
• Primary Document Recap
• Derived Sketches/Parts
• Construction Assemblies and In Context Editing
• Mechanism Document Recap
• Part Libraries

OnShape Learning Pathways

• Top Down Design
• https://learn.onshape.com/learn/learning-path/top-down-design
• These lessons have more detailed instructions for each of the features we will be going over.

Top-Down Modeling

• Using a primary document to define the overall design and then using portions of that document to define the subsystem mechanisms.
• Updating the sketches and entines in the primary document will propagate changes to each subsystem document.

Multiple Documents and Versioning

• We create our robot in multiple documents
• The main robot assembly lives in document 0
• Each mechanism gets its own numbered document
• Versioning is a big advantage to multiple documents
• You can roll back a single mechanism to a previous state if a change isn’t working.
• It’s critical to manually create versions while working in multiple documents.
• Until a document is versioned the other documents won’t be able to see any updates.
• “Pin Reference”
• lets you stop an item from being included in the Uplated All Linked document list, useful for MKCAD documents.

The importance of the Origin

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• It’s critical that all the documents keep a consistent origin
• When inserting Part Studios into an assembly they default to their space relative to the origin so if we keep all the origins the same the Part Studio all naturally line up.
• Mating to the origin and using group mates are much easier ways to define objects in space and consistent origins allows us to do this.
• We recommend that the origin be the center of the robot at the level of the field carpet.
• This way measurements from the origin can tell you a robots height, half its width, and half its length.

Variables

• Variables allow you to use the same values in multiple places and allow for easy editing.
• When starting a document think about the variables you will use the most and create variables for them
• Variables that are only used in one place aren’t required but may be helpful if you believe it’s a value that you may want to change often.

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• Variable Library Feature Script
• Allows you to use the same variables across documents
• Items such as hole sizes, common additives, machine tolerances, can all be included in main document or your teams parts library.
• https://www.chiefdelphi.com/t/major-featurescript-release-plate-suite-variable-suite/395889

Primary Assembly

• In the primary robot document (#0) we will keep the primary assembly
• The Primary Assembly will import each of the mechanism assemblies
• You can fix the same part that is fixed in the mechanism assemblies to keep it in a consistent spot.

Primary Sketches

• In the primary robot document (#0) we will keep a part studio with the primary sketches
• The Primary Sketches part studio will hold 3 or more sketches that define the overall characteristics of the robot.

Space Allocation Volumes/Shapes

• Allows you to visualize the volumes that a mechanism must fit into
• Robot volumes may include the full frame perimeter and height of the robot and the expansion limits of the rules, including height expansion limits
• Subsystem volumes may be generic shapes showing how much space is allocated for a subsystem or you may make it more detailed and include simple shape representations of the mechanism itself. (Block CAD, Crayola CAD, etc)

Primary Document Recap

1. Includes the Primary Variable Library for robot wide variables
2. Includes the Primary Sketches part studio that has 3+ sketches defining much of the mechanisms geometry
3. Includes the Space Allocation part studio with simple shapes defining the 3D constraints of the robot and mechanisms
1. May also include simple block versions of mechanisms
4. Includes the Primary Assembly that will all the mechanism assemblies inserted into it.

Derived Sketches/Parts

• This is how we will import the primary sketches and volumes into our mechanism documents.

Construction Assemblies and In Context Editing

• They are used to allow us to do in context editing of a mechanism and pull dimensions from the rest of the robot when needed.
• Be careful when doing this as most things should be defined in the variable library, primary sketches and space allocations.
• If you are regularly referring to in context items for dimensions you may need to add more details to your primary document to include that information.

• In context editing is best used for copying hole and mounting locations across mechanisms
• “Set as Primary Instance”
• very useful for allowing you to update the context in a part studio. The option is in the assembly though.

Mechanism Document Recap

• Assembly
• Named with the same number and name as the document.
• This is what will be inserted in the Primary Assembly
• Part Studios
• Here is where you will model all the parts for the Mechanism
• You can include/derive the Variable Libraries, Primary Sketches, Space Allocations in these part studios.
• Construction Assembly
• This assembly includes the Primary Assembly so you can use it when you edit the Part Studio’s in context.

Part Libraries and COTS Parts

• Use the official MKCAD files at all times
• You don’t want people using different copies of MKCAD documents and you end up with slightly different models of the same part.
• Create your own CAD library for parts that are not included in MKCAD.
• Don’t directly import COTS STEP files into your robot documents.