Image Sensor Motion Delta Prediction for MCU Polling
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Solution Overview
Problem
In optical navigation devices, the non-synchronization between the frame rate of the image sensor and the MCU polling rate leads to inconsistencies in motion delta output, affecting the accuracy of position computation.
Innovation Solution
An image sensing system control method that predicts the velocity of the image sensor, calculates the time duration between frame and polling times, and uses this information to predict and output motion deltas, thereby reducing the impact of synchronization issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the image sensor captures frames at a predetermined frame rate and the MCU polls for motion delta, then motion delta can be obtained for position computation, but non-synchronization between frame rate and polling rate causes inconsistent motion delta output and affects position computation accuracy
Solution Approach 1:
The patent applies preliminary action by predicting the velocity of the image sensor before the polling occurs. The system calculates a predicted velocity based on previous motion data and uses this prediction to compute a predicted motion delta that corresponds to the polling time, rather than waiting for the actual frame to be captured. This advance prediction ensures that motion delta values are consistently available for each polling event regardless of frame synchronization.
Solution Approach 2:
The patent changes the parameter of motion delta calculation from being frame-based to being time-duration-based. Instead of outputting motion delta values that correspond to fixed frame intervals, the system calculates motion delta based on the actual time duration between frames and polling events. By using the formula: predicted motion delta = predicted velocity × time duration, the system adapts the motion delta output to match the actual polling timing, ensuring consistency across different polling rates.
2Adaptability or versatility
If the MCU polling rate and image sensor frame rate are different, then the system can operate in different modes (active or standby), but the non-synchronization causes the MCU to receive different numbers of motion deltas for different pollings
Solution Approach 1:
The patent applies dynamics by making the motion delta calculation adaptive to varying polling rates and frame rates. The system dynamically adjusts the predicted motion delta based on the actual time duration between frames and polling events. This dynamic adjustment allows the system to maintain consistent motion delta output whether operating in active mode with high frame rates or standby mode with lower frame rates, regardless of the MCU polling rate.
3Device complexity
If motion delta is computed between different frames captured at fixed intervals, then the computation is simple, but the fixed interval assumption breaks down when polling occurs at non-synchronized times
Solution Approach 1:
The patent changes the computation approach from using fixed frame intervals to using actual measured time durations. The system calculates the actual time duration between the frame capture time and the polling time, and uses this measured duration in the velocity multiplication formula. This parameter change maintains computational simplicity while improving accuracy, as it only requires adding a time duration measurement step without complex synchronization logic.
Data Source
AI summary
An image sensing system control method, comprising: (a) predicting a first velocity of the image sensor; (b) calculating a first time duration between a first frame time and a first polling time after the first frame time, wherein the image sensor captures a first frame at the first frame time and receives a first polling from the control circuit at the first polling time; and (c) calculating a first predicted motion delta of the first time duration according to the first velocity and the first time duration.