Atomizer/studies/uav_arm_optimization

Drone Camera Gimbal Support Arm Optimization

Engineering Scenario

Application: Professional aerial cinematography drone Component: Camera gimbal support arm Goal: Lightweight design for extended flight time while maintaining camera stability

Problem Statement

The current production arm weighs 145g and meets all requirements. Marketing wants to advertise "30% longer flight time" by reducing weight. Your task: optimize the arm geometry to minimize weight while ensuring it doesn't compromise camera stability or structural integrity.

Real-World Constraints

• Camera Payload: 850g (camera + gimbal mechanism)
• Maximum Deflection: 1.5mm (required for image stabilization systems)
• Material: Aluminum 6061-T6 (aerospace grade)
• Safety Factor: 2.3 on yield strength (276 MPa)
• Vibration Avoidance: Natural frequency must be > 150 Hz to avoid coupling with rotor frequencies (80-120 Hz)

Multi-Objective Optimization

This study explores the trade-off between two competing objectives:

Objectives

1. MINIMIZE Mass - Every gram saved increases flight time

   • Target: < 120g (17% weight savings)
   • Current: 145g baseline

2. MAXIMIZE Fundamental Frequency - Higher frequency = better vibration isolation

   • Target: > 150 Hz (safety margin above 80-120 Hz rotor range)
   • Trade-off: Lighter designs typically have lower frequencies

Constraints

1. Max Displacement < 1.5mm under 850g load
2. Max von Mises Stress < 120 MPa (Al 6061-T6 yield = 276 MPa, SF = 2.3)
3. Natural Frequency > 150 Hz (hard requirement)

Design Variables (Parametric Beam Model)

• beam_half_core_thickness: 20-30 mm (affects stiffness and weight)
• beam_face_thickness: 1-3 mm (face sheets for bending resistance)
• holes_diameter: 180-280 mm (lightening holes for weight reduction)
• hole_count: 8-14 (number of lightening holes)

Expected Outcomes

• Pareto Front: Shows designs on the optimal trade-off curve between mass and frequency
• Weight Savings: 10-20% reduction from 145g baseline
• Constraint Analysis: Clear visualization of which constraints are active/limiting
• Design Insights: Understand how design variables affect both objectives

Study Configuration

• Protocol: Protocol 11 (Multi-Objective Optimization)
• Sampler: NSGA-II (genetic algorithm for Pareto fronts)
• Trials: 30 (sufficient for Pareto front exploration)
• Duration: ~1-2 hours (2-4 minutes per trial)

Files in This Study

drone_gimbal_arm_optimization/
├── 1_setup/
│   ├── model/
│   │   ├── Beam.prt              # Parametric beam geometry
│   │   ├── Beam_sim1.sim         # Simulation setup (needs modal analysis!)
│   │   └── Beam_fem1.fem         # Finite element mesh
│   ├── optimization_config.json   # Multi-objective config
│   └── workflow_config.json       # Extractor definitions
├── 2_results/                     # Created during optimization
│   ├── study.db                   # Optuna database
│   ├── optimization_history_incremental.json
│   └── ...
├── run_optimization.py            # Main execution script
├── NX_FILE_MODIFICATIONS_REQUIRED.md  # IMPORTANT: Read this first!
└── README.md                      # This file

Before You Run

CRITICAL: You MUST modify the NX simulation files before running.

Read NX_FILE_MODIFICATIONS_REQUIRED.md for detailed instructions.

Summary of Required Changes:

1. Add Modal Analysis Solution (SOL 103) to extract natural frequencies
2. Update static load to 8.34 N (850g camera payload)
3. Verify material is Al 7075-T6

Running the Optimization

# Quick test (5 trials, ~10-20 minutes)
cd studies/drone_gimbal_arm_optimization
python run_optimization.py --trials 5

# Full study (30 trials, ~1-2 hours)
python run_optimization.py --trials 30

# Resume existing study
python run_optimization.py --resume

Monitoring in Dashboard

While optimization runs, monitor in real-time:

1. Start Dashboard Backend (separate terminal):

   cd atomizer-dashboard/backend
   python -m uvicorn api.main:app --reload --port 8000
   

2. Start Dashboard Frontend (another terminal):

   cd atomizer-dashboard/frontend
   npm run dev
   

3. Open Browser: http://localhost:3003

4. Select Study: drone_gimbal_arm_optimization

Dashboard Features You'll See

• Real-time trial updates via WebSocket
• Pareto front visualization (mass vs frequency scatter plot)
• Constraint violation tracking (which trials failed which constraints)
• Progress monitoring (30 trials total)
• New best notifications when Pareto front expands

Interpreting Results

Pareto Front Analysis

The Pareto front will show:

• Lower-left designs: Lighter but lower frequency (more prone to vibration)
• Upper-right designs: Heavier but higher frequency (better vibration isolation)
• Middle region: Balanced trade-offs

Selecting Final Design

Choose based on flight profile:

• Stable hovering flights: Select lighter design (mass priority)
• Dynamic maneuvers: Select higher frequency design (vibration priority)
• Balanced missions: Mid-Pareto design

Constraint Active Check

Look for designs where:

• Displacement constraint is just satisfied (1.4-1.5mm) = efficient use of deflection budget
• Frequency constraint is marginally above 150 Hz = not over-designed
• Stress well below limit = safety margin confirmed

Why This is Realistic

This scenario reflects real engineering trade-offs in aerospace:

1. Weight vs Performance: Classic aerospace dilemma
2. Multi-Physics Constraints: Static strength + dynamic vibration
3. Safety Margins: Realistic stress limits with safety factors
4. Operational Requirements: Specific to drone camera applications
5. Pareto Decision-Making: No single "best" design, requires engineering judgment

Comparison with Bracket Study

Unlike the bracket study (single objective), this study shows:

• Multiple optimal solutions (Pareto set, not single optimum)
• Trade-off visualization (can't optimize both objectives simultaneously)
• Richer decision support (choose based on priorities)
• More complex analysis (static + modal)

Next Steps After Optimization

1. Review Pareto front in dashboard
2. Select 2-3 candidate designs from different regions of Pareto front
3. Detailed FEA verification of selected candidates
4. Fatigue analysis for repeated flight cycles
5. Prototype testing to validate predictions
6. Down-select based on test results

Technical Notes

• Uses NSGA-II multi-objective optimizer (Optuna)
• Handles 3 constraints with penalty methods
• Extracts 4 quantities from 2 different solutions (static + modal)
• Fully automated - no manual intervention during run
• Results compatible with all dashboard visualization features

Questions?

This study demonstrates the full power of multi-objective optimization for real engineering problems. The Pareto front provides engineering insights that single-objective optimization cannot offer.