Robot Vision Control via Coordinate Transformation

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Solution Overview

Problem

Existing robot vision systems face accuracy and cost issues due to vibration and deformation of the camera stand, leading to frequent recalibration needs and increased complexity in environments with disturbances.

Innovation Solution

A method involving a fixed camera and reference markers, where a measuring device attached to the robot calculates the relative positional relationship between the workpiece and the robot using images captured by both the fixed camera and the hand camera, allowing for high-accuracy control with reduced hardware and cost.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the stiffness of the camera stand is increased to prevent vibration and deformation, then the position stability of the vision sensor is improved, but the hardware size and manufacturing cost increase

Engineering Contradiction:
Improveposition stability of vision sensorVSAvoidhardware size and structure
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent replaces the mechanical solution (stiff camera stand) with a computational solution (coordinate transformation). Instead of physically preventing vibration through structural stiffness, the system mathematically transforms coordinates between the vision sensor coordinate system and robot coordinate system, eliminating the need for a rigid mechanical support structure.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the approach from physical parameter optimization (stiffness) to coordinate system parameter transformation. By introducing transformation parameters between coordinate systems, the system achieves position accuracy without requiring changes to the physical stiffness of the camera stand.

Inventive Principle:
Principle #35Parameter changes

2Manufacturing precision

If the camera stand is made more rigid to maintain calibration accuracy, then the manufacturing precision is improved, but the cost and hardware complexity increase

Engineering Contradiction:
Improvecalibration accuracyVSAvoidmanufacturing cost
Core Design Contradiction:
Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The patent substitutes mechanical rigidity requirements with computational coordinate transformation. The calibration accuracy is maintained through mathematical transformation between coordinate systems rather than through expensive rigid mechanical structures, simplifying manufacturing and reducing costs.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

3Measurement precision

If frequent recalibration is performed to maintain accuracy in vibrating environments, then the measurement precision is improved, but the productivity decreases

Engineering Contradiction:
Improveposition and orientation accuracyVSAvoidrobot operation efficiency
Core Design Contradiction:
Measurement precisionVSProductivity

Solution Approach 1:

The patent performs coordinate transformation calibration in advance and stores the transformation parameters. This preliminary calibration eliminates the need for frequent recalibration during robot operations, maintaining measurement precision while avoiding interruptions to productivity.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system uses the stored transformation parameters to continuously correct position and orientation measurements without requiring active recalibration. This feedback mechanism maintains accuracy throughout operation without stopping the robot for recalibration.

Inventive Principle:
Principle #23Feedback

4Stability of the object's composition

If a complex camera stand structure is used to prevent vibration, then the stability is improved, but the device complexity increases

Engineering Contradiction:
Improvecamera stand stabilityVSAvoidcamera stand structure
Core Design Contradiction:
Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The patent replaces complex mechanical stabilization structures with a computational coordinate transformation system. The stability is achieved through mathematical correction rather than mechanical design, significantly simplifying the camera stand structure.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentUS11254008B2Method and device of controlling robot system
Publication Date: 2022.02.22 CANON KK
  • US11254008B2 patent drawing
  • US11254008B2 patent drawing
  • US11254008B2 patent drawing

AI summary

A method of controlling a robot system includes measuring, capturing, and calculating. A measuring device attached to the robot measures a position and an orientation of a marker with respect to the robot. An imaging device captures an image of the marker and a workpiece. A control device calculates a relative positional relationship between the workpiece and the robot in accordance with a result obtained by the measuring device and with the image captured by the imaging device.