Nested Scan Mirror Layout for Compact Lidar Rotation Sensing
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Solution Overview
Problem
Existing lidar sensors have a large volume, which becomes a burden when multiple sensors are mounted on autonomous vehicles, and their sensing performance is degraded when not exposed to the outside, necessitating a reduction in size while maintaining effectiveness.
Innovation Solution
A lidar sensor with a driving motor covered under an inclined surface of a scan mirror having an A-shaped cross-section, utilizing a magnet and hall sensor for rotation detection, and a control unit to calculate and control the rotation angle for laser scanning, distinguishing between scan and non-scan regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the driving motor is positioned outside the scan mirror structure, then the motor can be easily accessed for maintenance and replacement, but the overall volume of the lidar sensor increases
Solution Approach 1:
The driving motor is nested within the hollow interior space of the scan mirror, with the motor shaft directly connected to the rotation axis of the scan mirror. This nesting arrangement eliminates the need for external motor mounting structures and external drive shafts, significantly reducing the overall sensor volume while maintaining full motor functionality for rotating the scan mirror.
2Reliability
If the scan mirror has a traditional closed structure, then the internal components are protected, but the volume increases and rotation detection becomes more complex
Solution Approach 1:
The scan mirror is designed with an asymmetric hollow structure that opens at the bottom surface, eliminating the need for a closed bottom cover. This asymmetric design reduces the overall volume compared to a traditional closed mirror structure while the side walls provide sufficient protection for the internally nested motor. The open bottom allows direct access for rotation detection without requiring complex detection mechanisms.
3Measurement precision
If a complex rotation detection system is used, then the rotation angle can be precisely measured, but the device complexity increases
Solution Approach 1:
The mechanical rotation detection system is replaced with a magnetic field-based detection system. A magnet is attached to the motor shaft, and a Hall sensor mounted on the sensor housing detects the magnet's position as the motor rotates. This substitution eliminates complex mechanical encoders or potentiometers, reducing device complexity while providing sufficient rotation angle measurement precision for controlling the laser scanning process.
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
The solution reduces the overall volume of the lidar sensor by eliminating unnecessary height components and allows for efficient rotation detection and laser scanning, enhancing the sensor's performance and compatibility with vehicle installations.
Implementation Method 1
a hall sensor may be formed at the bottom surface of the lidar sensor, in response to the position where the magnet is formed
Data Source
AI summary
Provided is a lidar sensor having a driving motor of which the entire portion is covered under an inclined surface of a scan mirror having an opened bottom surface and an A-shaped cross-section. A rotating shaft of the driving motor may be connected to the bottom of a backing surface disposed under the inclined surface, a magnet may be disposed at the bottom of one or more of the backing surface and a support surface which are connected to the inclined surface of the scan mirror, and a hall sensor may be disposed at the bottom surface of the lidar sensor corresponding to the position where the magnet is disposed.