Robot Tool Deformation Calculation Using Image-Based Target Positioning
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Solution Overview
Problem
Industrial robots face inaccuracies in calculating the position of the tool tip due to elastic deformation of rigid and joint parts, and existing methods do not account for tool deformation, requiring expensive three-dimensional measuring devices for accurate deformation measurement.
Innovation Solution
A robot tool deformation amount calculator system that captures images of measurement targets on the robot and tool, calculates their positions, and determines tool deformation based on the robot's posture, using a simple configuration to estimate deformation amounts without requiring expensive equipment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a three-dimensional measuring device such as a laser tracker is used to obtain the degree of elastic deformation of the tool, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent uses a camera to capture images of measurement targets as a simplified copy of the complex three-dimensional measuring device. Instead of using expensive laser trackers, the system creates a visual representation of tool deformation through 2D images, which are then processed to calculate deformation amounts. This replaces complex physical measuring equipment with a simpler optical copying system.
Solution Approach 2:
The patent replaces the mechanical three-dimensional measuring device with an optical system (camera) combined with image processing. The mechanical laser tracker is substituted by capturing images of measurement targets with a camera and calculating deformation through coordinate processing, thereby replacing a complex mechanical system with a simpler optical and computational approach.
2Device complexity
If calculation is performed assuming rigid body parts and joint parts do not deform, then device complexity is reduced, but manufacturing precision deteriorates due to elastic deformation errors
Solution Approach 1:
The patent implements a feedback mechanism where the actual tool tip position is measured using measurement targets and camera imaging, then compared with the calculated position based on joint angles. The difference (deformation amount) is fed back to correct the position calculation, allowing the system to account for elastic deformation without increasing overall system complexity. This closed-loop approach maintains simplicity while improving precision.
Solution Approach 2:
The patent changes the calculation parameters by introducing deformation amount calculations based on measured position differences. Instead of using only rigid body kinematics, the system incorporates deformation parameters derived from image-based measurements, allowing accurate tool tip positioning while maintaining a relatively simple calculation framework.
3Ease of operation
If existing calibration methods are used to determine mechanical parameters, then ease of operation is improved, but measurement precision deteriorates because tool deformation is not accounted for
Solution Approach 1:
The patent merges the calibration process with the deformation measurement process. Instead of performing calibration and deformation measurement as separate operations, the system combines them into a unified process where measurement targets are used for both calibration and deformation assessment. This integration maintains operational simplicity while simultaneously achieving accurate deformation accounting.
Solution Approach 2:
The measurement targets serve multiple functions: they are used for camera calibration, for determining tool attachment surface position, and for measuring tool deformation. This multi-functionality allows the system to achieve high measurement precision without adding separate dedicated measurement devices, thereby maintaining ease of operation while improving accuracy.
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 accurate calculation of tool and robot deformation, improving the precision of tool tip positioning without the need for costly three-dimensional measuring devices, facilitating more accurate robotic operations.
Implementation Method 1
a first image in which a first measurement target positioned at a tool attachment part of a tip of a robot is captured and a second image in which a second measurement target positioned at a predetermined part more on a tip side of the tool than the tool attachment part is captured
Data Source
AI summary
A robot tool deformation amount calculator 300 includes an image acquisition unit 341 which acquires a first image in which a first measurement target 10 positioned at a tool attachment surface 122 of a tip of a robot 100 is captured and a second image in which a second measurement target 20 positioned on a tip 202 of the tool 200 is captured, a first measurement target position calculation unit 342 which calculates a position of the first measurement target 10 based on the first image, a second measurement target position calculation unit 343 which calculates a position of the second measurement target 20 based on the second image, and a tool deformation amount calculation unit 345 which calculates a deformation amount of the tool 2(X) in accordance with a posture of the robot 100 based on the position of the first measurement target 10 and the position of the second measurement target 20.