Lidar Sensor Pose Calibration with Portable Reference Boards
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Solution Overview
Problem
Existing lidar sensor calibration methods for vehicles are cumbersome, expensive, and difficult to transport, and they struggle with maintaining sensor accuracy due to manufacturing issues and environmental movements, necessitating a simpler and more portable calibration system.
Innovation Solution
A system using multiple calibration boards with specific geometric configurations, allowing lidar scans to cross edges and determine reference planes, followed by a plane transform to calculate the lidar sensor's pose, thereby calibrating the sensor accurately.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If complex calibration rooms with square pillars are used, then calibration accuracy is improved, but device complexity and portability deteriorate
Solution Approach 1:
The patent divides the calibration system into multiple independent calibration boards (at least two) that can be separately positioned and configured. Each board contains simplified geometric features (edges and corners) that collectively provide the necessary reference points for calibration, eliminating the need for a single complex calibration room structure.
Solution Approach 2:
The patent uses multiple calibration boards with standardized geometric patterns that replicate the essential calibration features needed. Instead of requiring a unique complex calibration room, multiple simpler boards with similar geometric characteristics can be used interchangeably to achieve the same calibration accuracy.
2Measurement precision
If large calibration rooms are used, then calibration accuracy is improved, but ease of transport deteriorates
Solution Approach 1:
The calibration system is segmented into multiple portable calibration boards that can be individually transported and assembled as needed. Each board is a self-contained unit with standardized geometric features, allowing the calibration setup to be broken down into manageable, transportable components rather than requiring a large fixed calibration room.
Solution Approach 2:
The patent transitions from using a large two-dimensional calibration room to using multiple three-dimensional calibration boards with vertical edges and corners. This dimensional change allows the calibration features to be concentrated in compact vertical structures that occupy minimal horizontal space, dramatically improving portability while maintaining calibration accuracy.
3Ease of manufacture
If photo camera calibration is used, then equipment cost is reduced, but measurement precision deteriorates
Solution Approach 1:
The lidar sensor performs its own calibration by directly scanning the geometric features on the calibration boards and processing the reflected scan data itself. This self-calibration approach eliminates the need for separate camera equipment and complex camera-to-lidar transformation calculations, reducing equipment costs while maintaining high measurement precision through direct geometric measurement.
Solution Approach 2:
The patent replaces the optical-mechanical camera calibration system with a direct lidar-based geometric measurement system. Instead of using a camera to capture images and compute transformations, the lidar sensor directly measures the geometric features (edges and corners) of the calibration boards, substituting optical measurement with direct laser ranging and eliminating the intermediate computational transformation step.
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 precise and cost-effective calibration of lidar sensors by determining their pose relative to the vehicle, improving navigation accuracy and reducing the need for large, bulky calibration setups.
Implementation Method 1
cause the lidar sensor to receive a reflection of the lidar scan from the calibration boards
Data Source
AI summary
A system for determining pose of a lidar sensor in an environment in order to calibrate the lidar sensor. The system includes at least two calibration boards, each having a first edge and a second edge. There is a controller coupled to the lidar sensor to cause the lidar sensor to direct a lidar scan at the calibration boards. The controller causes the lidar sensor to receive a reflection of the lidar scan from the calibration boards and determine locations of a first crossing point on the first edge and a second crossing point on the second edge of the calibration boards. The controller determines a reference plane defined by the first and second crossing points of each of the calibration boards, performs a plane transform of the reference frame to obtain a lidar sensor plane and determine from the lidar sensor plane a pose of the lidar sensor.