MEMS Mirror Phase Estimation via Rotation Matrix
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Solution Overview
Problem
Current techniques for estimating the phase and amplitude of sense signals in resonant MEMS devices are inefficient and inaccurate, particularly when few computational resources are available, leading to suboptimal control of MEMS mirrors in laser scanning projectors.
Innovation Solution
A method using a rotation-matrix approach to generate reference cosine and sine waves, followed by low-pass filtering and a 4-quadrant CORDIC technique to determine phase shift and amplitude, allowing for accurate estimation and adjustment of drive signals to maintain desired phase and amplitude settings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional techniques are used to estimate phase and amplitude, then the control system can operate, but the measurement precision is insufficient and computational resources are excessive
Solution Approach 1:
The patent replaces complex computational methods with a mathematical model-based approach. Instead of using heavy signal processing algorithms to estimate phase and amplitude, the system uses the known resonant behavior of the MEMS mirror (modeled as a second-order filter) to directly calculate these parameters from the sense signal, substituting mechanical/computational complexity with mathematical simplicity
Solution Approach 2:
The patent changes the approach from estimating parameters through complex signal processing to calculating them through mathematical transformations of the sense signal. By using the resonant frequency and quality factor characteristics of the MEMS mirror, the system transforms the sense signal into phase and amplitude information through straightforward mathematical operations rather than complex computations
2Measurement precision
If more computational resources are available, then phase and amplitude estimation can be more accurate, but the device becomes less suitable for portable applications
Solution Approach 1:
The patent substitutes energy-intensive computational algorithms with mathematically efficient calculations. By leveraging the resonant characteristics of the MEMS mirror, the system achieves accurate phase and amplitude estimation through simple mathematical operations that consume minimal computational energy, making the device suitable for portable applications with limited power resources
3Use of energy by moving object
If simple computational operations are used, then energy consumption is reduced, but the measurement precision deteriorates
Solution Approach 1:
The patent changes the fundamental approach from computational estimation to mathematical calculation. By using the known resonant frequency and quality factor parameters of the MEMS mirror, the system derives phase and amplitude information through straightforward mathematical transformations of the sense signal, achieving both low energy consumption and high measurement precision simultaneously
Data Source
AI summary
Techniques to be described herein are based upon the combination of a digital lock-in amplifier approach with a numerical method to yield accurate estimations of the amplitude and phase of a sense signal obtained from a movement sensor associated with a resonant MEMS device such as a MEMS mirror. The techniques described herein are efficient from a computational point of view, in a manner which is suitable for applications in which the implementing hardware is to follow size and power consumption constraints.