# WIA-MED-006 PHASE 3: Precision Control Specification

## Overview
This specification defines precision control requirements including motion scaling, tremor filtering, and navigation.

## 1. Motion Scaling

### 1.1 Scaling Ratios
- **1:1**: Fast repositioning, no scaling
- **3:1**: Standard surgery (default)
- **5:1**: High-precision tasks
- **10:1**: Microsurgery (optional)

### 1.2 Scaling Requirements
- **Transition**: Smooth blending, <100ms transition time
- **Linearity**: ±2% across full range
- **User Control**: Surgeon-selectable via foot pedal or voice
- **Adaptive**: Optional context-aware auto-adjustment

### 1.3 Implementation
```
X_slave = (1/S) × X_master
where S = scaling factor (1, 3, 5, or 10)

Adaptive scaling:
IF (near critical structure) THEN S = 5
ELSE IF (velocity > threshold) THEN S = 1  
ELSE S = 3
```

## 2. Tremor Filtering

### 2.1 Tremor Characteristics
- Physiological tremor: 8-12 Hz, 0.1-0.5mm amplitude
- Fatigue tremor: 4-8 Hz, 0.5-2.0mm amplitude
- Pathological tremor: 4-12 Hz, 1.0-5.0mm amplitude

### 2.2 Filtering Requirements
- **Tremor Reduction**: ≥90%
- **Signal Delay**: ≤10ms
- **Phase Distortion**: ≤5°
- **Passband**: DC to 3 Hz (preserve intended motion)

### 2.3 Multi-Stage Filter
1. **Low-pass**: Butterworth, 3 Hz cutoff
2. **Kalman Filter**: State estimation [position, velocity, acceleration]
3. **Adaptive**: Increase strength when tremor detected
4. **Predictive**: 100ms forward prediction for latency compensation

## 3. Position Control

### 3.1 Accuracy Requirements
- **Position Accuracy**: ±0.1mm
- **Repeatability**: ±0.02mm  
- **Path Accuracy**: ±0.5mm
- **Settling Time**: <100ms

### 3.2 Control Loop
- **Update Rate**: ≥1000 Hz
- **Controller**: PID or model-based
- **Feedforward**: Optional for improved tracking

## 4. Collision Avoidance

### 4.1 Real-time Collision Detection
- **Check Rate**: 100 Hz minimum
- **Geometric Model**: Bounding volumes (cylinders, capsules)
- **Safety Distance**: 10mm warning, 5mm stop
- **Response**: Immediate stop + haptic/visual warning

### 4.2 Prediction
- **Lookahead**: 500ms trajectory prediction
- **Alternative Paths**: Suggest collision-free routes
- **Recovery**: Safe retraction to collision-free position

## 5. Virtual Fixtures

### 5.1 Fixture Types
- **Forbidden Regions**: Repulsive force around critical structures
- **Guidance Regions**: Attractive force along planned path
- **Scaling Regions**: Variable scaling by workspace zone

### 5.2 Implementation
```
Forbidden Region:
IF tool enters forbidden zone THEN
  F_repulsive = K × penetration_depth
  Push tool away + haptic warning
END IF

Guidance:
F_guidance = K_guide × path_error
```

## 6. Image-Guided Navigation

### 6.1 Registration
- **Target Registration Error (TRE)**: <2mm
- **Fiducial Registration Error (FRE)**: <1mm
- **Methods**: Anatomical landmarks, surface matching, paired-point

### 6.2 Tracking
- **Update Rate**: 30 Hz minimum
- **Accuracy**: ±1mm throughout workspace
- **Deformation**: Real-time tissue tracking (optional)

### 6.3 AR Overlays
- Vascular maps (red: arteries, blue: veins)
- Tumor boundaries (yellow outlines)
- Safety zones (red forbidden regions)
- Planned trajectories (green paths)
- Distance measurements

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**Status**: ✅ Complete  
**Version**: 1.0.0  
**Date**: 2025-01-01

© 2025 WIA · MIT License