Event-Based RSO Sensing for Faint Object Tracking and Rotation Analysis
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Solution Overview
Problem
Frame-based vision sensors face challenges in monitoring faint objects due to finite exposure times, insufficient temporal resolution, and pixel saturation during bright reflections, making it difficult to accurately characterize resident space objects (RSOs) for space domain awareness (SDA) tasks such as collision prevention, satellite health assessment, and orbit propagation.
Innovation Solution
Utilizing event-based vision sensors to generate event signals in response to changes, allowing for high-temporal resolution monitoring of RSOs by determining event rates and brightness variations, and optionally using multiple sensors with different color filters to differentiate materials and infer rotational speeds and orientations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If frame-based vision sensors are used to monitor faint RSOs, then long exposure times can make faint objects visible, but temporal resolution becomes insufficient and pixel saturation occurs during bright reflections
Solution Approach 1:
The patent transitions from static frame-based sensors with fixed exposure times to dynamic event-based sensors that continuously update pixel states. Each pixel independently integrates photons over time and generates events when brightness changes exceed a threshold, enabling adaptive temporal resolution that is high during bright reflections (short effective exposure) and maintains sensitivity during faint object detection (long effective integration), thus resolving the contradiction between detectability and temporal resolution
Solution Approach 2:
The patent changes the fundamental operating parameter of the sensor from fixed exposure time frames to variable event-triggered integration. Event-based sensors dynamically adjust their effective exposure time based on scene brightness changes, allowing long integration for faint objects without saturation during bright reflections, thereby simultaneously improving both detectability of faint objects and temporal resolution measurement precision
2Illumination intensity
If frame-based sensors use long exposure times to detect faint objects, then faint objects become visible, but pixel saturation occurs during bright reflections
Solution Approach 1:
Event-based sensors dynamically adapt their integration time at each pixel based on local brightness changes. When a bright reflection occurs, the pixel quickly reaches its brightness threshold and stops integrating (generating fewer events), preventing saturation. For faint objects, the pixel continues integrating over longer periods, accumulating sufficient signal. This dynamic adaptation resolves the contradiction between detecting faint objects and avoiding pixel saturation during bright reflections
Solution Approach 2:
The event-based sensor maintains continuous photon integration across all pixels simultaneously, rather than using discrete frames. This continuous operation allows each pixel to independently accumulate signal for faint objects while automatically limiting integration during bright reflections through event thresholding, eliminating the need to choose between long exposure for faint objects and short exposure to avoid saturation
3Loss of information
If frame-based sensors are used for RSO characterization, then brightness measurements can be obtained, but the finite exposure times limit the ability to capture rapid changes
Solution Approach 1:
The patent replaces static frame-based temporal sampling with dynamic event-based temporal sampling. Event-based sensors generate measurements continuously whenever brightness changes occur, providing high temporal resolution for rapid changes while maintaining the ability to measure absolute brightness through integration of events over time. This resolves the contradiction by making temporal resolution adaptive rather than fixed, capturing rapid changes without losing brightness measurement capability
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
Enables high-temporal resolution characterization of RSOs with improved accuracy in determining rotational speeds, material types, and reducing ambiguity in rotation rates, facilitating precise tracking and classification of RSOs for SDA applications.
Implementation Method 1
an event-based vision sensor... generate event signals, and optionally associated brightness measurements, in response to changes it senses in the remote region
Data Source
AI summary
Disclosed herein is a method for remote monitoring, comprising determining, from event signals obtained from an event-based vision sensor, a rate of those event signals generated in response to changes associated with a specific object and, optionally, determining a brightness of the specific object from exposure measurements associated with the event signals.