Asynchronous Solar Sensor Photovoltaic Centroid Calculation
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Solution Overview
Problem
Existing solar sensors for space navigation face challenges with high power consumption, long reading times, and unnecessary bandwidth and power consumption due to processing non-illuminated pixels, as well as the complexity of calculating the sun's position with external processing circuitry.
Innovation Solution
The proposed asynchronous solar sensor uses photodiodes operating in the photovoltaic region to generate power instead of consuming it, and incorporates a simple processing module to directly calculate the centroid of the illuminated region within the sensor, reducing data output and hardware complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If digital solar sensors use synchronous image sensors to detect sun position, then measurement precision is achieved, but reading time increases and power consumption rises due to sequential pixel scanning
Solution Approach 1:
The patent inverts the conventional synchronous scanning approach by using asynchronous pixels that autonomously generate voltage pulses proportional to illumination intensity. Instead of sequentially reading all pixels, the system processes pixels as they naturally signal their illumination state, eliminating the time-consuming sequential scanning while maintaining centroid calculation accuracy for sun position detection
Solution Approach 2:
The patent implements preliminary action by having pixels pre-process their own illumination data through autonomous voltage pulse generation. The pixels themselves perform the initial measurement and signal generation, eliminating the need for subsequent sequential reading and processing steps that would otherwise be required to achieve accurate sun position detection
2Measurement precision
If synchronous solar sensors scan all pixels to determine centroid, then measurement precision is maintained, but power consumption increases due to processing non-illuminated pixels
Solution Approach 1:
The patent extracts only the useful information from the pixel matrix by using asynchronous pixels that generate voltage pulses solely when illuminated. Non-illuminated pixels remain inactive and generate no signals, allowing the system to extract centroid information from only the relevant illuminated region without wasting power on processing dark pixels
Solution Approach 2:
The patent implements self-service by enabling pixels to autonomously determine their illumination state and generate appropriate voltage pulses without external control. Each pixel independently contributes to the centroid calculation only when illuminated, eliminating the need for external scanning control and reducing overall power consumption while maintaining measurement precision
3Speed
If asynchronous solar sensors use photodiodes in reverse region, then response speed improves, but power consumption increases due to reverse current flow
Solution Approach 1:
The patent applies parameter changes by switching the photodiode operating region from reverse bias to photovoltaic mode. This parameter change fundamentally alters the current-voltage characteristics, allowing the photodiodes to generate power through photocurrent in the first quadrant rather than consuming power through reverse current, while maintaining the fast response characteristics needed for space navigation
4Measurement precision
If external processing circuitry calculates sun position, then measurement precision is achieved, but device complexity increases
Solution Approach 1:
The patent merges the processing function directly into the pixel matrix by using the autonomous voltage pulse generation and arbitration logic embedded within each pixel. The centroid calculation is performed by integrating the voltage pulses from illuminated pixels through the arbitration logic, combining detection and processing functions within the sensor itself rather than requiring separate external processing circuitry
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution significantly reduces power consumption, increases acquisition speed, and simplifies hardware requirements, making it more suitable for space applications where low latency and reduced complexity are critical.
Implementation Method 1
Each of the pixels of the matrix comprises a photodiode (17) working in a photovoltaic region
Data Source
AI summary
The invention relates to an asynchronous solar sensor, capable of calculating the relative position of the sun with respect to the centroid thereof, which comprises a very low-power pixel matrix, with N rows and M columns, with a photodiode working in a photovoltaic region in each pixel, wherein the pixels are connected in a common row line and a common column line; a pin-hole optics module, linked to the matrix, and comprising a hole through which a light passes, an illuminated region being generated on the matrix; and a processing module, connected to the common row line and to the common column line of the pixel matrix, configured directly to determine the centroid of the illuminated region.