Magnetic Sensing for LiDAR Scanning Mirror Angle
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Solution Overview
Problem
Existing LiDAR systems face challenges in accurately sensing the angular position of scanning mirrors in real-time, particularly due to limitations in integration, compactness, and complexity of capacitive, piezoresistive, and optical sensing methods.
Innovation Solution
A magnetic sensing system utilizing a permanent magnet and a wire coil, where one is mounted on the scanning mirror and the other off it, inducing a voltage as they rotate, allowing a controller to determine the rotation angle and enable adaptive feedback control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If capacitive sensing is used to measure the rotation angle of the MEMS mirror, then integration capability is improved, but the sensor structure cannot be reduced to a compact size
Solution Approach 1:
The patent replaces the mechanical capacitive sensing structure with a magnetic sensing system consisting of a permanent magnet and wire coil. This substitution eliminates the need for complex capacitive electrode structures while maintaining integration capability, as the magnetic components can be miniaturized and integrated into the MEMS mirror assembly without requiring large structural modifications.
Solution Approach 2:
The patent changes the sensing mechanism from electrical capacitance measurement to magnetic field interaction. By using a permanent magnet and wire coil configuration, the system achieves compact dimensions while maintaining integration feasibility, as the magnetic field interaction occurs in a small volume around the mirror without requiring extensive structural changes.
2Measurement precision
If optical sensing using a position sensitive device (PSD) is used to measure the rotation angle, then measurement precision is improved, but the device becomes expensive and difficult to integrate with the scanning mirror
Solution Approach 1:
The patent replaces the optical PSD sensing system with a magnetic sensing approach using a permanent magnet and wire coil. This substitution eliminates the need for complex optical paths, PSD detectors, and associated alignment mechanisms, thereby reducing integration difficulty and cost while maintaining the ability to measure rotation angle through magnetic field interaction that occurs naturally during mirror rotation.
Solution Approach 2:
The patent introduces a magnetic field as an intermediary between the moving mirror and the sensing system. The permanent magnet attached to or near the mirror creates a magnetic field that interacts with the wire coil, providing a direct coupling mechanism that eliminates the need for complex optical intermediaries and simplifies the overall system integration.
3Ease of manufacture
If piezoresistive sensing is used to measure the rotation angle, then ease of integration is improved, but a specific readout circuit (e.g., Wheatstone bridge) needs to be designed
Solution Approach 1:
The patent replaces the piezoresistive sensing mechanism with magnetic sensing using a permanent magnet and wire coil. This substitution eliminates the need for piezoresistive elements and their associated Wheatstone bridge readout circuits, as the magnetic interaction directly induces voltage in the coil according to Faraday's law, providing a simpler electrical readout mechanism that maintains integration ease while reducing circuit complexity.
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
Enables precise real-time sensing of the scanning mirror's angular position, improving LiDAR system accuracy and resolution by allowing closed-loop feedback control, suitable for applications in autonomous driving and high-definition mapping.
Implementation Method 1
a wire coil configured to rotate relative to the permanent magnet when the scanning mirror rotates, causing an induced voltage in the wire coil
Data Source
AI summary
Embodiments of the disclosure provide magnetic sensing systems and methods for a scanning mirror. An exemplary magnetic sensing system includes a permanent magnet configured to provide a magnetic field. The magnetic sensing system further includes a wire coil configured to rotate relative to the permanent magnet when the scanning mirror rotates, causing an induced voltage in the wire coil. One of the permanent magnet and the wire coil locates on and rotates with the scanning mirror and the other locates off the scanning mirror. The magnetic sensing system also includes at least one controller configured to determine a rotation angle of the scanning mirror based on the induced voltage in the wire coil.