- This is intended to be advice for FRC teams scrambling to quickly scour online resources for ideas on how to proceed with their own robot designs.
- Ideally, the CAD model of the robot should contain a few Major Subassemblies that bolt together to complete the Top Assembly (which represents the complete robot).
- Each of those major subassemblies may further comprise smaller subassemblies, creating a hierarchical assembly structure.
- To illustrate this, I will use the example of the Cranberry Alarm Ri3D - 2026 - Mini Fridge. This video reveals a robot which was designed and built in 3 days. The CAD model has been shared here. This CAD model does not have a hierarchical assembly structure and is thus pretty difficult to navigate. (In fairness to the team that produced it, they were scrambling to get something out in 3 days so they can be forgiven.)
- Let's assume that the robot team decides to implement some of the features of this robot into their own design.
- The first step would be to identify the major subsystem assemblies as shown below:
| Name of subsystem | Image |
|---|---|
| Chassis |  |
| Hopper & Intake |  |
| Feed & Shooter |  |
- But it would certainly be advantageous to structure the CAD file this way.
- It would make it easier to navigate.
- Multiple people could work simultaneously on the robot design, each on a different subsystem.
- It would make it easier to design the mechanical connections between subsystems
- It would make it easier to facilitate service in the pit if subsystems were designed to be quickly removable.
- I would suggest that our robot design team undertake to replicate the Cranberry Alarm robot but using a top down assembly structure.
- This would be excellent practice for all on the CAD team.
- It would be helpful to further break the major assemblies into component subassemblies.
- The shooter (AndyMark Launcher in a Box) is rotationally mounted to operate as a rotating turret, so this is is an obvious sub-assembly.
- The intake & hopper could be broken into component subassemblies, making it possible to show the pivoting motion of the intake w/r/t the fixed part of the hopper, and showing the moving part of the hopper being pushed to slide out.
- The CAD model could then be used to demonstrate mechanisms as animations.
- This futher allows the CAD model to be used to investigate part clearances during the animation cycle, discovering (and avoiding) any interferences early in the design process.