Vibration Damping

Camera vibration isolation for sharp aerial images on the Bennu drone.

Why It Matters

The Raspberry Pi HQ Camera uses a rolling shutter (IMX477). Rolling shutter sensors are sensitive to vibration — high-frequency vibrations cause:

• Jello effect (wobbly distortion in video/images)
• Motion blur from micro-movements during exposure
• Reduced Laplacian variance (detected as "blur" by quality scoring)

Damping Strategy

Camera Mount

The camera mount uses TPU (flexible filament) vibration isolators between the rigid CF-PETG frame and the camera plate:

Frame (CF-PETG, rigid)
  │
  ├── TPU damper pads (4x, Shore 95A)
  │
  └── Camera plate (CF-PETG)
        └── HQ Camera + 6mm lens

Design Parameters

Parameter	Value	Notes
Damper material	TPU Shore 95A	Soft enough to isolate, firm enough to not oscillate
Damper count	4	One per corner of camera plate
Damper height	6mm	Provides ~2mm compression under load
Camera mass	~45g	HQ Camera + 6mm CS-mount lens
First resonance	~25 Hz (estimated)	Below typical prop frequencies (~80-150 Hz)

Motor Balancing

Propeller and motor imbalance is the primary vibration source. Before flight:

1. Balance propellers using a magnetic balancer
2. Check motor screws — loose screws amplify vibration
3. Verify prop adapters — collets must be tight

PX4 Vibration Monitoring

PX4 reports vibration levels via the estimator_status topic:

• Good: < 15 m/s² peak
• Marginal: 15–30 m/s² — damping may need improvement
• Bad: > 30 m/s² — flight controller may reject GPS fusion

Check in QGroundControl: Analyze → Vibration

Testing

After assembly, verify vibration isolation:

1. Power on, arm (props removed), throttle to 50%
2. Check PX4 vibration in QGC
3. Take a test image — check Laplacian variance > 100 (sharp)
4. If blurry: increase TPU damper thickness or switch to softer Shore rating