Lidar Mirror Corner Radius for Drag Reduction
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Solution Overview
Problem
Rotating sensor units, such as Lidar, face issues with drag and performance degradation due to high rotation speeds, leading to reduced longevity and efficiency in detecting external objects for autonomous and manual driving vehicles.
Innovation Solution
The implementation of a mirror assembly with rounded, filleted, beveled, or chamfered corners, along with aerodynamic baffles, to reduce aerodynamic drag and dynamic pressure, coupled with a control system to manage the rotation and light emission, enhances the performance and longevity of the sensor units.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the mirror assembly rotates at high speed to enable rapid environmental scanning, then the detection speed and coverage are improved, but aerodynamic drag and torque increase, reducing efficiency and longevity
Solution Approach 1:
The patent applies curvature by rounding the corners of the mirror assembly with a radius of curvature of at least 0.1 mm. This curved geometry reduces aerodynamic drag by minimizing turbulence and vortex formation at the corners during high-speed rotation, thereby reducing energy loss while maintaining the required rotation speed for rapid environmental scanning.
Solution Approach 2:
The patent changes the geometric parameters of the mirror assembly by implementing rounded corners with specific radius values (at least 0.1 mm, optionally 0.1-1.0 mm, or up to 2.0 mm). This parameter modification optimizes the aerodynamic characteristics, reducing drag coefficients and allowing the system to maintain high rotation speeds with reduced energy consumption.
2Productivity
If the mirror assembly rotates at high speed to improve detection coverage, then the scanning efficiency is improved, but torque requirements increase, impacting motor size and power consumption
Solution Approach 1:
The rounded corners of the mirror assembly reduce aerodynamic resistance, which directly decreases the torque required to maintain high rotation speeds. This allows the scanning system to operate more efficiently with reduced motor power requirements while maintaining high productivity in environmental scanning.
3Ease of manufacture
If sharp corners are used on the mirror assembly to minimize material usage, then manufacturing cost is reduced, but aerodynamic drag and dynamic pressure increase at high rotation speeds
Solution Approach 1:
The patent implements rounded corners with a radius of curvature of at least 0.1 mm, which can be achieved through standard manufacturing processes such as CNC machining, molding, or polishing. This moderate level of curvature significantly reduces aerodynamic drag and dynamic pressure at high rotation speeds while remaining compatible with conventional manufacturing methods, thus maintaining ease of manufacture.
Solution Approach 2:
The patent specifies optimal parameter ranges for the corner radius (at least 0.1 mm, optionally 0.1-1.0 mm, or up to 2.0 mm) that balance manufacturing simplicity with aerodynamic performance. These parameter specifications allow manufacturers to achieve the desired drag reduction using standard production techniques without requiring complex or expensive manufacturing processes.
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 configuration minimizes drag and torque, improving the sensor's ability to detect objects effectively and reducing power consumption, thereby enhancing the overall performance and reliability of the sensor assembly.
Implementation Method 1
the set of edges may rounded with a selected radius of curvature of at least 0.1 mm, or may be otherwise truncated, which reduces localized maximums of airflow behind the edges and correspondingly the dynamic pressure adjacent to the edges
Implementation Method 2
A laser light source is configured to emit light so that the emitted light is reflected off of one or more of the reflective surfaces and is directed to one or more locations in an environment external to the rotary sensor apparatus
Data Source
AI summary
Aspects of the technology employ sensors having high speed rotating mirror assemblies. For instance, the sensors may be Lidar sensors configured to detect people and other objects in an area of interest. A given mirror assembly may have a triangular or other geometric cross-sectional shape. The reflective faces of the mirror assembly may connect along edges or corners. In order to minimize wind drag and torque issues, the corners are rounded, filleted, beveled, chamfered or otherwise truncated. Such truncation may extend the length of the mirror side. The mirror assembly may employ one or more beam stops, light baffles and/or acoustic/aerodynamic baffles. These sensors may be employed with self-driving or manual driven vehicles or other equipment. The sensors may also be used in and around buildings.


