Accurate and Cost-Effective Micro Sun Sensor based on CMOS Black Sun Effect.

Area of Science:

• Optics and Photonics
• Aerospace Engineering
• Robotics

Background:

• Conventional sun sensors struggle with accurate sun center detection due to image noise and glare.
• Developing cost-effective and accurate sun sensors is crucial for space missions and solar energy applications.

Purpose of the Study:

• To present an accurate and cost-effective micro sun sensor utilizing the "black sun" effect.
• To demonstrate the sensor's high accuracy and reliability in various operating conditions.

Main Methods:

• The "black sun" phenomenon is exploited to precisely extract the sun center, even from irregular and noisy images.
• A micro CMOS image sensor (1 mm × 1 mm, 250 × 250 pixels) is employed.
• Two application modes are implemented: stationary (single sensor) and non-stationary (six sensors in icosahedron geometry).
• Kalman filtering and sensor fusion techniques are applied to enhance measurement accuracy.

Main Results:

• High accuracy achieved even with a small, low-resolution image sensor.
• Stationary mode achieved 0.013° accuracy with Kalman filtering.
• Non-stationary mode achieved 0.05° accuracy by fusing measurements from three sensors.
• The "black sun" effect ensures precision is independent of the sun's location on the image plane.

Conclusions:

• The proposed micro sun sensor offers a cost-effective and highly accurate solution for sun vector extraction.
• The "black sun" effect overcomes limitations of conventional sensors, enabling reliable performance in challenging imaging conditions.
• The sensor is suitable for diverse applications, including heliostat tracking, solar panel orientation, and moving platform navigation.