FSOC Terminal Motion Compensation for Beam Pointing Accuracy
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Solution Overview
Problem
FSOC systems with narrow beamwidth and long transmission distances experience significant tracking and pointing accuracy errors due to internal and external disturbances, leading to frequent connection interruptions and excessive power consumption from reactive beacon beam corrections.
Innovation Solution
A combination of proactive and reactive methodologies using feedforward and feedback gain scheduling approaches to estimate and correct tracking and pointing errors, minimizing the need for frequent beacon beam transmissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If reactive beacon beam transmissions are used to correct tracking errors, then tracking accuracy is improved, but power consumption increases excessively
Solution Approach 1:
The system performs preliminary action by proactively estimating future tracking errors using feedforward control based on predicted external disturbances (wind, mount vibration, bird effects) before they actually occur. This allows the system to pre-adjust the optical beam pointing position, reducing the need for frequent reactive beacon beam transmissions and thereby significantly lowering power consumption while maintaining tracking accuracy.
Solution Approach 2:
The system implements feedback control by continuously monitoring actual tracking errors and using this information to refine future error predictions. The reactive estimation component uses measured tracking deviations to correct the feedforward predictions, creating a closed-loop control system that optimizes beacon beam transmission timing and reduces unnecessary power consumption.
2Productivity
If narrow beamwidth is used for long-distance transmission, then transmission efficiency is improved, but tracking and pointing accuracy errors become more pronounced
Solution Approach 1:
The system proactively estimates tracking and pointing errors caused by external disturbances (wind, mount vibration, bird landing/departing) before they affect the narrow beam alignment. By predicting these errors in advance and pre-adjusting the optical assembly positioning, the system maintains accurate pointing with narrow beams over long distances without sacrificing transmission efficiency.
Solution Approach 2:
The system applies preliminary anti-action by calculating compensatory adjustments to counteract anticipated external disturbances before they occur. The feedforward control component generates correction signals that preemptively offset the expected impact of wind, mount vibration, or bird effects on the narrow optical beam, thereby maintaining pointing accuracy throughout the long transmission distance.
3Reliability
If frequent beacon beam transmissions are used to maintain connection, then connection reliability is improved, but power consumption increases
Solution Approach 1:
The system uses proactive error estimation to predict when tracking deviations will occur and prepares correction signals in advance. This allows the system to maintain connection reliability by making precise, targeted adjustments only when necessary, rather than transmitting frequent beacon beams continuously, thereby significantly reducing power consumption while preserving connection integrity.
Solution Approach 2:
The system transitions from continuous or frequent periodic beacon beam transmissions to a more efficient periodic action pattern where beacon beams are transmitted only when predicted tracking errors exceed a threshold. This optimized periodic transmission schedule maintains connection reliability while minimizing power consumption by eliminating unnecessary transmissions during stable tracking conditions.
Data Source
AI summary
The technology relates to free-space optical communication systems that correct for errors in tracking and pointing accuracy to maintain connection integrity. Such systems can both proactively and reactively correct for errors in tracking performance and pointing accuracy of terminals within the system. An aspect includes receiving information indicative of at least one external disturbance associated with a communication device. A determination is made for a proactive estimation indicative of a first error associated with an effect of the at least one external disturbance at a current timestep. A determination is made for a reactive estimation indicative of a second error associated with the effect of the at least one external disturbance at a previous timestep. A final control signal is determined based on the proactive estimation and the reactive estimation. A controller is able to actuate an optical assembly of the communication device based on the determined final control signal.