LiDAR Galvanometer Mirror Frequency Control for Stable Scanning
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Solution Overview
Problem
The scanning angle of a mirror in LiDAR systems changes due to deviations in resonance frequency caused by environmental factors like temperature, leading to instability in amplitude gain, which existing phase-locked loop systems fail to effectively manage.
Innovation Solution
A closed-loop control method that adjusts the frequency of the control signal based on feedback from the mirror's motion state, using a linear closed-loop control algorithm to maintain stable amplitude gain by determining and correcting errors in amplitude gain relative to a preset threshold.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a phase-locked loop system is used to control the mirror scanning frequency, then the system can operate at resonance frequency, but the scanning angle becomes unstable when resonance frequency deviates due to environmental factors like temperature
Solution Approach 1:
The patent implements a closed-loop feedback control system that continuously monitors the actual amplitude gain of the mirror and compares it with a preset threshold. When deviation is detected, the system automatically adjusts the driving frequency to restore the amplitude gain to the threshold value, thereby maintaining stable scanning angle despite resonance frequency shifts caused by temperature variations or other environmental factors.
Solution Approach 2:
The control system performs self-adjustment by automatically detecting amplitude gain deviations and correcting the driving frequency without external intervention. The system uses its own output signal as reference, compares it with the feedback signal from the mirror motion, and autonomously tunes the frequency to maintain optimal scanning conditions.
2Speed
If the driving frequency is fixed at resonance frequency, then the mirror achieves maximum scanning amplitude, but environmental temperature changes cause resonance frequency deviation and amplitude gain instability
Solution Approach 1:
The patent dynamically adjusts the driving frequency parameter based on real-time amplitude gain feedback. Instead of maintaining a fixed resonance frequency, the system continuously modifies the driving frequency to compensate for temperature-induced resonance shifts, ensuring the mirror operates at the optimal frequency that maintains the preset amplitude gain threshold despite environmental changes.
3Reliability
If closed-loop control is implemented to maintain stable amplitude gain, then scanning angle stability is improved, but the device complexity increases
Solution Approach 1:
The control device integrates multiple functions into a single unified system: it generates the driving signal, acquires feedback signals from the mirror motion, processes the feedback to determine amplitude gain, compares the gain with the preset threshold, and adjusts the driving frequency accordingly. This multi-functional integration reduces the need for separate dedicated components for each function, thereby limiting the increase in device complexity while achieving stable amplitude gain control.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Ensures the mirror scans with a stable amplitude gain, maintaining a specified scanning angle by continuously adjusting the frequency to compensate for resonance frequency deviations, thereby stabilizing the scanning process.
Implementation Method 1
A main working principle of the mirror is combining horizontal scanning and vertical scanning into two-dimensional scanning, and forming a two-dimensional planar array by performing scanning through specular reflection when a laser beam reaches the vibrating mirror.
Implementation Method 2
The mirror is driven by an input single-frequency signal to perform scanning through a simple harmonic motion. The mirror can reach a suitable angle during scanning within a safe gain only when working on resonance frequency.
Data Source
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AI summary
Embodiments of this application disclose a mirror control method and device and LiDAR, pertaining to the field of LiDAR. The method includes: outputting a control signal, where the control signal is used to control the mirror to perform scanning; detecting a feedback signal of the scanning mirror; determining an actual amplitude gain of the mirror based on the feedback signal, and determining an error of the actual amplitude gain relative to a preset amplitude gain threshold; and determining a frequency adjustment based on the error, adjusting the frequency based on the frequency adjustment, and obtaining an output signal. In the embodiments of this application, stability of a scanning angle of the mirror can be maintained when resonance frequency of the mirror deviates.