CAD Level 3 - Robot Subsystem Design

Learning Objective

Design complete functional robot subsystems incorporating mechanical calculations (gear ratios, forces, motion analysis), create dynamic assemblies with motion studies and interference detection, integrate electrical component placement and wire routing considerations into mechanical designs, and validate designs against FRC rules and performance requirements through simulation and analysis. This level typically takes a full season and centers on a capstone subsystem design reviewed and signed off by a mentor -- this is where students move from following instructions to operating independently and making informed design tradeoffs.

Prerequisites

• Mechanical Level 2 - Mechanism Design & Analysis
• CAD Level 2 - Part Design & Assembly

Primary Resources

• FRCDesign.org -- Mechanism Examples
• FRCDesign.org -- Design Handbook (Power Transmission)
• OnShape -- Advanced Part and Surfacing Design
• FRCDesign.org FeatureScripts

Tasks

1. Mechanism Design & Analysis

   • Study FRCDesign.org's mechanism design theory and worked examples
   • Study OnShape motion analysis tools and kinematic studies
   • Design complex multi-degree-of-freedom mechanisms (arms, elevators, intakes)
   • Calculate gear ratios, mechanical advantage, and power requirements
   • Analyze motion profiles and velocity/acceleration curves
   • Major Project: Design a complete robot arm subsystem
     • Multi-stage telescoping or articulated design
     • Include all mechanical calculations and motion analysis
   • Assessment: Present design rationale and calculations to a technical review panel

2. Advanced Assembly & Motion Studies

   • Master OnShape's advanced assembly features (linear patterns, circular patterns in assemblies)
   • Use advanced mates (gear, rack-and-pinion, cam-follower)
   • Create realistic motion studies showing mechanism operation
   • Perform interference detection during full range of motion
   • Optimize assemblies for serviceability and access
   • Integration Project: Create a full motion study of the robot arm
     • Show complete range of motion with realistic timing
     • Demonstrate no interferences throughout operation
     • Include motor mounting and drive system
   • Assessment: Motion study presentation showing design validation

3. Electrical Integration Planning

   • Learn OnShape's routing tools for cable management
   • Design with electrical component placement considerations
   • Plan wire routing paths and protection
   • Consider electromagnetic interference (EMI) in design
   • Coordinate with a Programming Level 2 student on sensor placement optimization
   • Collaborative Project: Work with an Electrical Level 2 student to integrate systems
     • Design mechanical mounts for all electrical components
     • Plan wire routing with appropriate service access
     • Consider weight distribution and center of gravity
   • Assessment: Joint presentation with the electrical team member

4. Design Validation & FRC Compliance

   • Master OnShape's simulation tools (FEA basics, stress analysis)
   • Validate designs against the current FRC game manual and robot rules
   • Perform basic finite element analysis on critical components
   • Create multiple design iterations based on analysis
   • Document design decisions and trade-offs
   • Validation Project: Complete a design review process for the robot arm
     • FRC rules compliance check
     • Stress analysis on critical components
     • Weight analysis and optimization
     • Design review presentation to the full team
   • Assessment: Successfully defend design choices in a formal design review

Level 3 Completion Requirements

• Mentor-reviewed capstone subsystem design, independently designed and documented
• Master OnShape's simulation and motion study tools
• Pass a formal design review with a technical panel
• Successfully integrate the design with electrical systems

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