Lidar Polygon Mirror Rotation Monitoring via Rotary Encoder
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Solution Overview
Problem
Existing lidar scanners face challenges with power requirements, heat dissipation, and physical dimensions, particularly in vehicle-mounted applications where precision and efficacy are critical but obstructed by these factors.
Innovation Solution
A lidar system incorporating a monitoring and correction technique using a photo-interrupter to detect full or partial revolutions of a polygon mirror, with dedicated circuitry and control systems to generate correction signals and alarms, ensuring stable rotational parameters and efficient operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the polygon mirror rotates at high speed to improve scanning coverage, then productivity increases, but manufacturing precision deteriorates due to rotational instability and drift
Solution Approach 1:
The system employs a rotary encoder to continuously monitor the polygon mirror's rotational position and speed, feeding this information back to a controller. The controller compares the actual rotation against desired parameters and generates correction signals to maintain precision during high-speed operation
Solution Approach 2:
The patent replaces mechanical correction mechanisms with an electronic control system that uses electrical signals from the rotary encoder and electronic actuators to adjust mirror rotation, eliminating the need for complex mechanical feedback devices
2Ease of operation
If the lidar system is designed with compact dimensions for vehicle mounting, then ease of operation improves, but heat dissipation worsens due to confined space
Solution Approach 1:
The patent optimizes the thermal management by transitioning from two-dimensional planar heat dissipation to three-dimensional heat sinks with extended surfaces, allowing heat to dissipate in multiple directions and increasing the effective heat dissipation area within the compact housing
3Productivity
If the polygon mirror block is enlarged to accommodate more reflective surfaces, then productivity increases through wider scanning angle, but weight increases affecting rotational stability
Solution Approach 1:
The patent employs composite materials for the polygon mirror block construction, combining lightweight materials with high reflectivity coatings to achieve the required scanning angle coverage while minimizing the overall weight and maintaining rotational dynamics performance
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 enhances the precision and reliability of lidar systems by stabilizing the rotational speed of the polygon mirror, improving power management, and optimizing the physical dimensions for reduced heat dissipation and aerodynamic efficiency.
Implementation Method 1
A monitoring/correction technique based on detecting full or partial revolutions of a polygon mirror using a photo-interrupter
Data Source
AI summary
A lidar system comprises a light source to emit pulses of light, a scanner, a receiver, and a controller. The scanner includes a rotatable polygon mirror with reflective surfaces, the reflective surfaces being angularly offset from one another along a periphery of the block. The scanner further includes a polygon mirror axle extending into the block, about which the block rotates, a rotary encoder having a rotational component with an axis of rotation aligned with the polygon mirror axle, the rotational component having one or more characteristics configured to cause the rotary encoder to return a signal, and a second mirror pivotable along an axis orthogonal to the polygon mirror axle. The controller is configured to determine a rotational parameter of the polygon mirror in response to the signal returned from the rotary encoder.