gh-omkamal-pypict-claude-skill/examples/gearbox-specification.md

Automotive Gearbox Control System - Specification

1. System Overview

The Automotive Gearbox Control System is an electronic control unit (ECU) that manages gear shifting in a semi-automatic transmission. The system monitors vehicle conditions and driver inputs to determine optimal gear selection and execute smooth gear changes.

2. System Components

2.1 Input Sensors

• Vehicle Speed Sensor: Measures current speed (0-200 km/h)
• Engine RPM Sensor: Measures engine revolutions (0-7000 RPM)
• Throttle Position Sensor: Measures accelerator pedal position (0-100%)
• Brake Pressure Sensor: Detects brake application
• Clutch Position Sensor: Monitors clutch engagement state
• Gear Position Sensor: Detects current gear (N, 1-6, R)

2.2 Driver Controls

• Gear Selector: Manual, Sport, Eco modes
• Shift Paddles: Manual up/down shift requests
• Clutch Pedal: Manual clutch control (if applicable)

2.3 Outputs

• Gear Actuator: Mechanical gear selection
• Clutch Actuator: Clutch engagement/disengagement
• Dashboard Display: Current gear indicator
• Warning Lights: System errors and alerts

3. Operating Modes

3.1 Manual Mode

• Driver has full control over gear selection
• System prevents invalid shifts (e.g., direct 5th to 1st)
• Rev-matching on downshifts
• Neutral safety: requires brake to shift out of Park/Neutral

3.2 Sport Mode

• Holds gears longer for higher RPM
• Faster gear changes
• Downshifts on hard braking
• Target shift points: 5000-6500 RPM

3.3 Eco Mode

• Early upshifts for fuel efficiency
• Target shift points: 2000-3000 RPM
• Smooth, gradual gear changes
• Skip-shift capability (e.g., 2nd to 4th)

4. Functional Requirements

4.1 Gear Shifting Logic

4.1.1 Upshift Conditions

• Eco Mode: Engine RPM > 2500 AND throttle < 40%
• Manual Mode: Driver paddle input OR RPM > 6000
• Sport Mode: Engine RPM > 5500

4.1.2 Downshift Conditions

• Eco Mode: Engine RPM < 1500 OR heavy throttle (>80%)
• Manual Mode: Driver paddle input OR RPM < 1200
• Sport Mode: Engine RPM < 2000 OR brake pressure > 50%

4.1.3 Prohibited Shifts

• Cannot shift from Reverse to any forward gear without stopping (speed = 0)
• Cannot shift to Reverse from any forward gear while moving (speed > 0)
• Cannot skip more than 2 gears in a single shift (except computer-controlled skip-shift)
• Cannot downshift if resulting RPM would exceed 7000 (red line protection)

4.2 Safety Features

4.2.1 Hill Start Assist

• Activates when: stopped on incline > 5% AND brake released
• Holds brake pressure for 2 seconds
• Prevents rollback

4.2.2 Overrun Protection

• Prevents downshift if resulting engine RPM > 6500
• Displays warning message to driver
• Ignores paddle input if unsafe

4.2.3 Stall Prevention

• Auto-downshift if engine RPM < 800 while moving
• Automatic neutral engagement if stopped for > 3 seconds in gear
• Clutch slip if speed drops below minimum for current gear

4.2.4 Neutral Safety

• Engine start only allowed in Park or Neutral
• Brake pedal required to shift from Park
• Reverse requires full stop (speed = 0 km/h)

4.3 Error Handling

4.3.1 Sensor Failures

• Speed Sensor Failure: Limit to current gear, disable automatic shifting
• RPM Sensor Failure: Use speed-based shift logic as fallback
• Throttle Sensor Failure: Default to conservative shift points
• Multiple Sensor Failures: Enter limp-home mode (3rd gear only)

4.3.2 Actuator Failures

• Gear Actuator Jam: Attempt 3 retries with 200ms delay
• Clutch Actuator Failure: Lock in current gear, display warning
• Hydraulic Pressure Low: Reduce shift speed, display warning

4.3.3 Temperature Management

• Normal Operation: 70-110°C
• High Temperature Warning: 110-130°C (reduce shift frequency)
• Critical Temperature: >130°C (limp-home mode, 3rd gear only)

5. Performance Requirements

5.1 Shift Times

• Eco Mode: 800-1200 ms per shift
• Manual Mode: 400-600 ms per shift
• Sport Mode: 150-300 ms per shift

5.2 Response Times

• Paddle Input: < 50 ms recognition
• Brake Detection: < 20 ms
• Emergency Neutral: < 100 ms

5.3 Reliability

• MTBF: > 150,000 km
• Shift Success Rate: > 99.5%
• False Error Rate: < 0.1%

6. Environmental Conditions

6.1 Operating Temperature

• Normal: -20°C to +50°C ambient
• Gearbox Oil: -10°C to +130°C

6.2 Altitude

• Sea Level to 3000m: Normal operation
• 3000m to 5000m: Adjusted shift points for reduced air density

6.3 Weather Conditions

• Rain, snow, ice: Reduced shift aggressiveness
• Detection via wheel slip sensors and ABS integration

7. User Interface Requirements

7.1 Dashboard Display

• Current gear number (1-6, R, N, P)
• Selected mode (Manual, Sport, Eco)
• Shift indicator (up/down arrows)
• Warning messages (text + icon)

7.2 Warning Messages

• "Gearbox Overheating" (yellow)
• "Shift Not Possible" (red)
• "Service Required" (yellow)
• "Limp-Home Mode Active" (red)

7.3 User Feedback

• Shift confirmation (subtle indicator flash)
• Paddle input acknowledgment (haptic feedback if available)
• Audio warning for critical errors

8. Integration Requirements

8.1 Engine Control Unit (ECU)

• Torque reduction request during shifts
• RPM synchronization for smooth engagement
• Engine braking coordination

8.2 Anti-lock Braking System (ABS)

• Wheel slip detection for traction control
• Emergency braking gear hold
• Stability control integration

8.3 Electronic Stability Control (ESC)

• Torque vectoring support
• Drift mode compatibility (sport mode)
• Traction control coordination

9. Validation Requirements

9.1 Unit Testing

• Individual sensor input validation
• Shift logic decision trees
• Safety feature triggering

9.2 Integration Testing

• Multi-mode operation
• Sensor failure scenarios
• ECU communication

9.3 System Testing

• Real-world driving scenarios
• Extreme condition testing
• Long-term reliability testing

10. Constraints and Assumptions

10.1 Physical Constraints

• Maximum gear ratio: 1:6.5 (1st gear) to 1:0.85 (6th gear)
• Clutch engagement time: 200-400 ms
• Hydraulic system pressure: 8-12 bar

10.2 System Assumptions

• Sensors provide accurate readings within ±5% tolerance
• ECU communication latency < 10 ms
• Battery voltage maintained at 12-14V

10.3 Regulatory Compliance

• ISO 26262 (Automotive Safety Integrity Level - ASIL C)
• UNECE R13 (Braking regulations)
• Local emissions standards compliance