Visual Sensor Calibration Device for Obstacle-Avoiding Range Measurement
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Solution Overview
Problem
Existing calibration methods for visual sensors, particularly stereo cameras, lack the ability to efficiently set and measure a calibration range for a target mark to ensure precise calibration without manual intervention, especially when obstacles are present, and do not account for multiple cameras.
Innovation Solution
A calibration device and method that associates a robot coordinate system with an image coordinate system, allowing a target mark to be moved within a predetermined range to be detected by multiple cameras, with the ability to set and measure calibration ranges independently for each camera, ensuring the target mark remains within the view range and avoids obstacles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the target mark is moved through a wide area in the view range to improve calibration precision, then the calibration accuracy is improved, but the target mark may collide with obstacles
Solution Approach 1:
The system performs preliminary detection of the calibration range by moving the target mark to candidate positions and detecting whether each position is within the view range of each camera before actual calibration. This preliminary action identifies safe movement areas that avoid obstacles while maximizing the calibration range.
2Reliability
If the calibration range is set in the robot coordinate system to prevent obstacle collision, then safety is improved, but manual checking is required which reduces efficiency
Solution Approach 1:
The system automatically detects the calibration range by having the target mark move to candidate positions and automatically determining whether each position is within the view range of cameras. This self-service approach eliminates the need for manual checking while ensuring safety, thereby improving calibration efficiency.
3Measurement precision
If multiple cameras are used for stereo calibration, then three-dimensional measurement capability is improved, but each camera requires independent calibration which increases complexity
Solution Approach 1:
The system uses a single target mark that serves multiple cameras simultaneously. The target mark moves to positions that are detected by one or more cameras, and the same movement data is used for calibration of multiple cameras, reducing overall calibration complexity while maintaining three-dimensional measurement capability.
4Measurement precision
If the view range of a camera is too wide or too narrow for the prepared pattern, then high-precision calibration cannot be achieved, but adjusting the camera view range reduces flexibility
Solution Approach 1:
The system dynamically adjusts the calibration range based on the actual view range of each camera by detecting which candidate positions fall within the view range. This dynamic adaptation allows the system to achieve high-precision calibration within the available view range while maintaining flexibility to work with different camera configurations.
Data Source
AI summary
For calibration on a single camera or a stereo camera, a calibration range is set in advance in an image coordinate system and the calibration is performed in an arbitrary range. A visual sensor controller is a calibration device that associates a robot coordinate system at a robot and an image coordinate system at a camera by placing a target mark at the robot, moving the robot, and detecting the target mark at multiple points in a view of the camera. The calibration device comprises: an image range setting unit that sets an image range in the image coordinate system at the camera; and a calibration range measurement unit that measures an operation range for the robot corresponding to the image range before implementation of calibration by moving the robot and detecting the target mark.