Navigation Frame Rate Adjustment for Low-Power Displacement Sensing
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Solution Overview
Problem
Navigation devices, such as image-based mice, face high power consumption due to maintaining a frame rate higher than the polling frequency to account for oscillator frequency variations, leading to inefficiencies in displacement data reading.
Innovation Solution
A navigation device and system that adjust the frame period by determining the difference between the frame period and polling period using an internal oscillator's clock signal, allowing the frame rate to be minimized while ensuring accurate displacement reading by maintaining a margin between the frame and polling rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the frame rate is maintained higher than the polling frequency to account for oscillator frequency variations, then the reliability of displacement data reading is improved, but the power consumption increases
Solution Approach 1:
The frame rate is made dynamically adjustable rather than fixed. The system continuously monitors the actual frame rate achieved by the image sensor and compares it with the polling frequency, then adjusts the target frame rate accordingly. This dynamic adjustment allows the system to maintain reliability by ensuring the frame rate stays above the polling frequency while minimizing power consumption by operating at the lowest necessary frame rate.
Solution Approach 2:
The system implements a feedback mechanism where the actual frame rate is measured and used to control the frame rate setting. The processor reads the actual frame rate from the image sensor, compares it with the polling frequency, and adjusts the target frame rate based on this comparison. This closed-loop feedback ensures that the frame rate is maintained at the minimum operable value needed for reliable displacement data reading.
2Use of energy by moving object
If the frame rate is reduced to minimum operable value, then the power consumption is reduced, but the reliability of displacement data reading may deteriorate due to oscillator frequency variations
Solution Approach 1:
The system dynamically adjusts the frame rate based on actual operating conditions rather than using a fixed conservative value. By continuously monitoring the actual frame rate and comparing it with the polling frequency, the system can safely operate at lower frame rates when conditions permit, reducing power consumption while maintaining reliability through active adjustment.
Solution Approach 2:
The feedback mechanism ensures that even when operating at minimum frame rates, the system maintains reliability by detecting when the actual frame rate falls below the polling frequency and adjusting upward when necessary. This feedback control allows the system to operate efficiently at low power consumption levels while having a safety mechanism to maintain data reading accuracy.
3Reliability
If a fixed frame rate with margin is used, then the displacement data reading reliability is ensured, but the frame rate cannot be optimized to minimum operable value
Solution Approach 1:
The system transitions from a static fixed frame rate approach to a dynamic adjustable frame rate system. The frame rate can now adapt to actual operating conditions, allowing the system to operate at the minimum operable value when possible while maintaining reliability through continuous monitoring and adjustment.
Solution Approach 2:
The feedback mechanism replaces the need for a fixed conservative margin by actively monitoring the actual frame rate and making real-time adjustments. This allows the system to achieve the reliability that a fixed margin would provide while actually operating at optimized, lower frame rates that reduce power consumption.
Data Source
AI summary
There is provided a frame rate adjusting method of a navigation device including: counting a frame period using a clock of a local oscillator of the navigation device; counting a polling period using the same clock; calculating a difference between the frame period and the polling period; adjusting a frame rate of the navigation device when the difference is smaller than a predetermined margin.