Camera-Based 6-DOF Target Measuring System
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Solution Overview
Problem
Current coordinate measurement devices, such as laser trackers and camera-based systems, are either too expensive or limited in accuracy and geometrical flexibility for common automated factory applications, particularly in precisely positioning robot end effectors and measuring six degrees of freedom.
Innovation Solution
A camera-based target coordinate measuring system that uses a rotatable camera with multiple light sources at known three-dimensional coordinates, angular measuring devices, and a processor to determine positional and rotational degrees of freedom without requiring a laser range finder, allowing for accurate measurement of objects in a cost-effective and geometrically flexible manner.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a laser tracker is used to measure three-dimensional coordinates with high accuracy, then measurement precision is improved, but device cost increases and the ability to measure six degrees of freedom is limited
Solution Approach 1:
The measurement function is segmented between a single camera for angular measurement and a retroreflector target with multiple light sources for distance measurement. This divides the expensive laser tracker functionality into separate, less costly components while maintaining six degrees of freedom measurement capability
Solution Approach 2:
A retroreflector target with multiple light sources is introduced as an intermediary between the camera and the object being measured. This target enables the camera to determine both distance and orientation information that would otherwise require expensive laser ranging equipment
2Measurement precision
If two or more cameras are used to improve measurement accuracy, then measurement precision is improved, but device cost increases and geometric flexibility is reduced
Solution Approach 1:
Instead of using multiple cameras to achieve accurate measurement, the invention inverts the approach by using a single camera combined with a specially designed retroreflector target. The target's multiple light sources at known coordinates provide the geometric information that would otherwise require multiple cameras
Solution Approach 2:
The retroreflector target acts as a portable reference frame with light sources at precisely known coordinates. This copying of spatial reference information to a physical target enables accurate measurement with a single camera, replacing the need for multiple expensive cameras
3Measurement precision
If cameras are spaced far apart to improve measurement accuracy, then measurement precision is improved, but the ability to see into narrow openings is reduced
Solution Approach 1:
The invention transitions from a multi-camera spatial arrangement to a single-camera system with rotational capability. By adding the dimension of camera rotation and using a retroreflector target with three-dimensional light source coordinates, the system achieves accurate measurement in confined spaces without requiring multiple cameras spaced far apart
4Device complexity
If a single camera is used to reduce cost, then device cost decreases, but measurement precision deteriorates
Solution Approach 1:
The invention changes the parameters of the retroreflector target by placing multiple light sources at precisely known three-dimensional coordinates. This transformation of the target from a simple reflector to a structured light source array enables a single camera to extract both distance and orientation information with high accuracy
Solution Approach 2:
The invention replaces the mechanical laser ranging system with an optical system using a camera and retroreflector. The retroreflector's multiple light sources provide distance information through angular measurement, substituting expensive laser distance measurement equipment with a less costly camera-based approach
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 provides high accuracy and flexibility in measuring six degrees of freedom, overcoming the limitations of existing technologies by maintaining precision over an extended range while being more cost-effective and capable of seeing into narrow openings.
Implementation Method 1
The rangefinder measures the distance to a retroreflector mounted on a probe
Implementation Method 2
a camera positioned near the rangefinder measures the angles to point light sources located on the probe
Data Source
AI summary
An embodiment may comprise a camera based target coordinate measuring system or apparatus for use in measuring the position of objects in manner that preserves a high level of accuracy. This high level of measurement accuracy is usually only associated with more expensive laser based devices. Many different arrangements are possible. Other embodiments may comprise related methods of using a camera based target coordinate measuring method for use in measuring the position of objects. Many variations on the methods are possible. For example, an embodiment may comprise a camera based coordinate measuring system for use in measuring the position of a target relative to at least one frame of reference without requiring use of a laser range finder for measuring distance comprising: at least three or more light sources located on a target at known three-dimensional coordinates relative to each other; at least one rotatable camera rotatable on about a first axis and a second axis wherein the camera records positions of the light sources; and two angular measuring devices to measure the angles of rotation of the camera about the first and second axes; and a processor for determining up to three positional degrees of freedom and up to three rotational degrees of freedom of the target.