Galvanometer Scanner Tilt-Angle Sensing via Induction Coils

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Solution Overview

Problem

Scanning mirror-based lidars require accurate measurement of the vibrating mirror's rotation or swing angle to determine spatial angular positions for obstacle detection, which is challenging due to the complexity of measuring the tilt angle of the vibrating mirror.

Innovation Solution

A method involving an excitation coil on the vibrating mirror's surface and an induction coil on an adjacent fixed surface is used to measure the tilt angle by detecting induction voltage signals, determining the distance variation between the coils, and calculating the tilt angle based on these signals.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If traditional methods are used to measure the tilt angle of the vibrating mirror, then the measurement can be obtained, but the system structure becomes complex and reliability decreases

Engineering Contradiction:

Improvetilt angle measurement accuracyVSAvoidsystem structure complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces complex mechanical tilt angle measurement systems with an electromagnetic sensing system. An excitation coil generates a magnetic field that interacts with the vibrating mirror, and an induction coil detects the induced voltage signal proportional to the tilt angle. This substitution of mechanical measurement with electromagnetic sensing simplifies the system structure while maintaining measurement precision.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces a magnetic field as an intermediary between the vibrating mirror and the induction coil. The excitation coil generates a magnetic field that penetrates the vibrating mirror, and the induction coil detects changes in this field caused by the mirror's tilt. This intermediary approach enables non-contact, simplified measurement of the tilt angle.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If traditional tilt angle measurement methods are implemented, then spatial angular position can be determined, but the measurement precision and reliability are insufficient

Engineering Contradiction:

Improvesystem reliabilityVSAvoidtilt angle measurement difficulty

Core Design Contradiction:

ReliabilityVSDifficulty of detecting and measuring

Solution Approach 1:

The patent replaces difficult mechanical tilt angle sensing with electromagnetic induction. The excitation coil generates a magnetic field that interacts with the vibrating mirror's motion, and the induction coil converts this interaction into a measurable voltage signal. This electromagnetic approach improves reliability by eliminating mechanical wear and contact issues while reducing measurement difficulty.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The vibrating mirror itself serves as part of the sensing system. As the mirror vibrates and tilts, it automatically modulates the magnetic field generated by the excitation coil, which the induction coil then detects. This self-service approach eliminates the need for separate, complex tilt angle sensors, improving both reliability and ease of measurement.

Inventive Principle:

Principle #25Self-service

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

This method provides precise measurement of the vibrating mirror's tilt angle, enhancing the accuracy of spatial positioning in lidar systems by simplifying the system structure and improving reliability.

Implementation Method 1

an induction coil is disposed on a fixed second surface adjacent to the first surface. A tilt angle of the first surface is determined according to an induction voltage signal of the induction coil to a current in the excitation coil

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentUS12578572B2Method for measuring deflection angle of galvanometer scanner, and laser radar using method

Publication Date: 2026.03.17 HESAI TECH CO LTD

AI summary

A method for measuring a tilt angle of a vibrating mirror, and a lidar using the method are provided. The vibrating mirror a first surface, an excitation coil is disposed on the first surface, the vibrating mirror is disposed adjacent to a fixed second surface, and an induction coil is disposed on the second surface. The method for measuring a tilt angle of a vibrating mirror includes: inputting a current signal to the excitation coil to generate an excitation current on the excitation coil; in response to receiving the current signal, detecting an induction voltage signal generated on the induction coil; determining a variation of distance between the excitation coil and the induction coil according to the induction voltage signal and an initial distance between the excitation coil and the induction coil; and determining a tilt angle of the first surface according to the variation of distance.