MEMS Mirror Phase Compensation for Periodic Jitter
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Solution Overview
Problem
Microelectromechanical systems (MEMS) mirrors in LIDAR systems suffer from periodic jitter due to asymmetry and chopping errors, leading to inaccuracies in position detection and laser pointing, which are not effectively compensated by existing technologies.
Innovation Solution
A MEMS oscillating system with a phase error detector and compensation circuit that generates and removes periodic jitter components from the phase error signal, improving the accuracy of mirror position detection and laser control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a MEMS mirror operates at resonance frequency for LIDAR scanning, then scanning speed and productivity are improved, but periodic jitter occurs due to asymmetry and chopping errors, degrading measurement precision
Solution Approach 1:
The patent implements a feedback mechanism where the phase error detector continuously monitors the actual phase of the MEMS mirror and compares it with the expected phase. The compensation circuit then adjusts the drive signal based on the detected phase error, creating a closed-loop control system that actively corrects periodic jitter while maintaining resonance frequency operation for high-speed scanning
Solution Approach 2:
The patent changes the parameters of the drive signal dynamically by adjusting its phase based on detected errors. The compensation circuit modifies the phase of the drive signal in real-time to counteract periodic jitter, allowing the system to maintain both high scanning speed and position detection accuracy by adapting the drive parameters rather than operating at fixed conditions
2Reliability
If chopping is used to compensate offset errors in operational amplifiers, then reliability is improved, but periodic jitter is introduced, worsening measurement precision
Solution Approach 1:
The patent converts the harmful periodic jitter introduced by chopping into a detectable and compensatable phase error. By using the phase error detector to identify the chopping-induced periodic variations and then compensating for them through phase adjustment, the system transforms the adverse effect of chopping into a manageable parameter that can be corrected, allowing offset compensation to proceed while maintaining measurement precision
3Ease of manufacture
If asymmetry in MEMS mirror structure is present from manufacturing, then manufacturing precision is reduced, but the mirror can still operate, however periodic jitter occurs, degrading position detection accuracy
Solution Approach 1:
The patent implements a self-service mechanism where the system automatically detects and compensates for its own manufacturing asymmetries. The phase error detector monitors the actual performance of the asymmetric mirror, and the compensation circuit adjusts the drive signal to correct for the asymmetry-induced periodic jitter, allowing the system to self-correct without requiring perfect manufacturing precision
Data Source
AI summary
Systems and methods are provided for compensating errors. A system includes a microelectromechanical systems (MEMS) oscillating structure configured to oscillate about a rotation axis; a phase error detector configured to generate a phase error signal based on measured event times and expected event times of the MEMS oscillating structure oscillating about the rotation axis; and a compensation circuit configured to receive the phase error signal, remove periodic jitter components in the phase error signal to generate a compensated phase error signal, and output the compensated phase error signal.