Laser Radar Angular Drift Correction via Virtual Fiducials
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Solution Overview
Problem
Laser radar systems with galvanometric x y scanners face significant angular drift issues due to temperature-related calibration drifts in capacitive or optical sensors, limiting three-dimensional accuracy, and existing solutions like fiducial targets are not practical for many applications as they require additional setup and obstruct the measurement area.
Innovation Solution
The implementation of a system with virtual fiducial targets and auxiliary laser sources within the xy scanner, which uses quad cells to calibrate the angular position of the scanning mirrors, providing a method to correct for angular drift internally without external targets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If fiducial targets are used to correct angular drift, then measurement precision is improved, but device complexity and ease of operation deteriorate due to additional setup requirements and obstruction of measurement area
Solution Approach 1:
The patent creates virtual copies of fiducial targets within the scanner's field of view rather than using physical targets. These virtual fiducials are generated by processing images of real fiducials that are projected or displayed within the scanner's scanning volume, allowing the system to reference known angular positions without requiring physical targets to be placed in the measurement area. This eliminates the operational complexity of setting up and removing physical fiducial targets while maintaining the angular accuracy correction capability.
2Reliability
If physical fiducial targets are deployed, then angular drift correction is achieved, but the measurement area is obstructed and setup time increases
Solution Approach 1:
The system generates virtual representations of fiducial targets that can be displayed or projected within the scanner's field of view without requiring physical targets to be placed in the measurement space. The virtual fiducials are created by processing images of real fiducials and storing their angular position data, enabling instantaneous reference without physical setup or removal operations that would consume time and obstruct the measurement area.
Solution Approach 2:
The patent replaces the mechanical placement and physical presence of fiducial targets with a computational approach. Instead of physically positioning targets in the measurement area, the system uses image processing and data storage to create virtual references. This substitution eliminates the mechanical setup and removal operations that cause time loss and area obstruction while maintaining the angular drift correction function.
3Ease of manufacture
If capacitive or optical sensors are used to measure mirror angles, then the scanner is inexpensive, but calibration drift with temperature reduces measurement precision
Solution Approach 1:
The system implements a feedback mechanism where virtual fiducials with known angular positions are periodically measured by the scanner. The measured positions are compared with the known positions, and any deviations caused by temperature-induced drift are detected. The system then uses this feedback information to correct the angular measurements, compensating for the calibration drift of the capacitive or optical sensors while maintaining the inexpensive scanner design.
Solution Approach 2:
The patent performs preliminary calibration by establishing the angular positions of virtual fiducials before they are used for measurement. These pre-calculated reference positions are stored and used during actual measurements to compensate for subsequent drift. By performing the calibration action in advance and storing the reference data, the system can correct for temperature-induced drift without requiring continuous expensive calibration procedures.
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 solution effectively corrects angular drift within the laser radar system, enhancing three-dimensional accuracy by using internal virtual fiducials and auxiliary lasers to calibrate the scanner, thus eliminating the need for external fiducial targets and maintaining operational efficiency in various applications.
Implementation Method 1
routing a plurality of auxiliary laser beams from the plurality of auxiliary laser sources into the xy scanner
Implementation Method 2
This scanner is composed of a pair of mirrors each rotated by galvanometric motors about axes that are approximately horizontal and roughly perpendicular to each other
Implementation Method 3
Measurement of the angle of the mirrors is currently done with a capacitive or optical sensor mounted on the galvanometric motor. Both of these sensors have significant calibration drifts with temperature.
Data Source
AI summary
A method of calibrating angle drift of a laser radar system is provided, in one aspect of the present invention. The method includes, providing a plurality of virtual fiducials into an xy scanner; and providing a plurality of auxiliary laser sources into the xy scanner. The method also includes, routing a plurality of auxiliary laser beams from the plurality of auxiliary laser sources into the xy scanner; and calibrating an angular position of a plurality of laser directing means. The methods provides creating a calibration signal for updating the angular position of a plurality of scanning mirrors.