Vehicle LiDAR Calibration Using Mirror Targets for Alignment Recovery
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
LiDAR sensors in vehicles require frequent recalibration due to mechanical disturbances, such as crashes or vibrations, to maintain accurate obstacle detection, which is challenging without returning to a manufacturer's plant or repair shop.
Innovation Solution
A method for calibrating LiDAR sensors using a target with a planar mirror and features, allowing for periodic or continuous calibration while the vehicle is parked or driving, by acquiring three-dimensional images and analyzing deviations from expected alignment to determine and correct positional and orientational errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If LiDAR sensor calibration is performed at a manufacturer's plant or repair shop, then calibration accuracy is maintained, but the complexity and time required for recalibration increases significantly
Solution Approach 1:
A calibration target serving as an intermediary object is introduced between the LiDAR sensor and the environment. This target contains a planar mirror and features that reflect laser pulses back to the sensor, enabling the sensor to self-calibrate by analyzing the reflected signals. The intermediary target provides known geometric references that allow calculation of alignment deviations without requiring complex external calibration equipment or facility infrastructure.
Solution Approach 2:
The LiDAR sensor performs self-calibration by using its own laser pulses and detectors to measure the calibration target. The sensor emits laser pulses that reflect off the planar mirror and return to the sensor, where the same detectors that measure external objects also detect the reflected pulses. This self-service mechanism eliminates the need for external calibration equipment, specialized facilities, or manual intervention, allowing the sensor to autonomously determine and correct its alignment deviations.
2Reliability
If LiDAR sensor recalibration is performed frequently to maintain accuracy after mechanical disturbances, then measurement reliability improves, but loss of time and operational downtime increases
Solution Approach 1:
The calibration target is pre-configured with a planar mirror and known features at predetermined positions and orientations before the calibration process begins. This preliminary setup creates a known reference framework that the LiDAR sensor can immediately use for self-calibration without requiring time-consuming measurement of the environment or complex computational geometry solving during the actual calibration execution.
Solution Approach 2:
The calibration system is designed to be dynamically deployable and executable at various locations and times. The calibration target can be positioned anywhere within the sensor's field of view, and the calibration process can be performed continuously or periodically without requiring the vehicle to be stationary or transported to a facility. The system adapts to different operational contexts, allowing calibration during normal operation or at convenient stopping points.
3Measurement precision
If LiDAR sensor alignment is continuously monitored and adjusted, then positioning precision is maintained, but device complexity and computational requirements increase
Solution Approach 1:
The LiDAR sensor continuously monitors its own alignment by detecting laser pulses reflected from the calibration target's planar mirror. The sensor compares the actual positions and orientations of the reflected features against their known predetermined positions, calculates alignment deviations, and generates feedback signals that trigger correction of the sensor's positioning. This closed-loop feedback mechanism maintains positioning precision through continuous self-monitoring and automatic adjustment without requiring complex external monitoring systems.
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 on-site recalibration of LiDAR sensors, ensuring safe and accurate long-term operation by maintaining precise alignment with the vehicle, reducing the need for frequent factory visits and improving reliability in dynamic environments.
Implementation Method 1
A LiDAR sensor can include one or more laser sources for emitting laser pulses, and one or more detectors for detecting reflected laser pulses. The LiDAR sensor measures the time it takes for each laser pulse to travel from the LiDAR sensor to an object within the sensor's field of view, then bounce off the object and return to the LiDAR sensor.
Implementation Method 2
The LiDAR sensor measures the time it takes for each laser pulse to travel from the LiDAR sensor to an object within the sensor's field of view, then bounce off the object and return to the LiDAR sensor. Based on the time of flight of the laser pulse, the LiDAR sensor determines how far away the object is from the LiDAR sensor.
Data Source
AI summary
A method of calibrating a LiDAR sensor mounted on a vehicle includes positioning the vehicle at a distance from a target including a planar mirror and features surrounding the mirror. The vehicle is positioned and oriented relative to the mirror so that an optical axis of the LiDAR sensor is nominally parallel to the optical axis of the mirror, and the target is nominally centered at a field of view of the LiDAR sensor. The method further includes acquiring, using the LiDAR sensor, a three-dimensional image of the target including images of the features of the target and a mirror image of the vehicle formed by the mirror. The method further includes determining a deviation from an expected alignment of the LiDAR sensor with respect to the vehicle by analyzing the images of the features and the mirror image of the vehicle in the three-dimensional image of the target.