LiDAR Calibration via Static Map Objects

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Solution Overview

Problem

Conventional sensor calibration methods for autonomous vehicles, such as LiDAR sensors, require additional resources and time, as they necessitate operating the vehicle in a confined environment to capture point cloud data from pre-selected objects, which diverts resources from other critical tasks like environment mapping and autonomous driving improvements.

Innovation Solution

A method and system for calibrating a first sensor, like a LiDAR, using statically mapped objects in a vehicle's environment, where point cloud data is captured and aligned with a pre-calibrated second sensor, such as a GPS IMU, to achieve calibration within a global coordinate system, allowing for iterative refinement of the transformation matrix for accurate calibration without additional resource expenditure.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional sensor calibration methods are used, then calibration accuracy can be achieved, but additional resources and time are required due to operating in confined environments

Engineering Contradiction:
Improvecalibration accuracyVSAvoidresource efficiency
Core Design Contradiction:
Measurement precisionVSProductivity

Solution Approach 1:

The system performs preliminary mapping of static objects in the environment before calibration is needed. This pre-established knowledge base of object locations and characteristics allows the calibration process to quickly identify suitable calibration targets without requiring confined environments or additional resource expenditure during actual calibration operations.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The calibration system utilizes naturally occurring static objects in the vehicle's operating environment as calibration targets, rather than requiring external calibration facilities. The vehicle's own sensors and the ambient environment serve the calibration function, eliminating the need for dedicated calibration resources and confined spaces.

Inventive Principle:
Principle #25Self-service

2Reliability

If conventional sensor calibration methods are used, then calibration can be performed, but time is lost diverting resources from other critical tasks

Engineering Contradiction:
Improvesensor calibrationVSAvoidcalibration time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The system performs calibration using static objects that are continuously present in the vehicle's operating environment during normal autonomous driving operations. This allows calibration to occur continuously alongside other critical tasks rather than requiring separate calibration sessions, eliminating time loss and maintaining sensor reliability without diverting resources.

Inventive Principle:
Principle #20Continuity of useful action

3Productivity

If static objects are used for calibration, then resource allocation is optimized, but the objects must satisfy specific criteria for accurate calibration

Engineering Contradiction:
Improveresource allocation efficiencyVSAvoidcalibration criteria verification
Core Design Contradiction:
ProductivityVSDifficulty of detecting and measuring

Solution Approach 1:

The system implements feedback mechanisms to verify that detected static objects satisfy the necessary calibration criteria. The calibration process monitors object characteristics, location accuracy, and sensor data quality, providing feedback to determine whether the current static object is suitable for calibration or if alternative objects should be selected, ensuring accurate calibration while maintaining resource efficiency.

Inventive Principle:
Principle #23Feedback

Data Source

PatentUS11982772B2Real-time sensor calibration and calibration verification based on statically mapped objects
Publication Date: 2024.05.14 PONY AI INC
  • US11982772B2 patent drawing
  • US11982772B2 patent drawing
  • US11982772B2 patent drawing

AI summary

Improved calibration of a vehicle sensor based on static objects detected within an environment being traversed by the vehicle is disclosed. A first sensor such as a LiDAR can be calibrated to a global coordinate system via a second pre-calibrated sensor such as a GPS IMU. A static object present in the environment is detected such as signage. A type of the detected object is determined from static map data. Point cloud data representative of the static object is captured by the first sensor and a first transformation matrix for performing a transformation from a local coordinate system of the first sensor to a local coordinate system of the second sensor is iteratively redetermined until a desired calibration accuracy is achieved. Transformation to the global coordinate system is then achieved via application of the first transformation matrix followed by a second known transformation matrix.