Robot Rotation Center Update via Visual Feedback

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Solution Overview

Problem

Existing robot control methods fail to accurately detect changes in the rotation center position during assembly tasks, leading to suboptimal performance when the position of the rotation center changes relative to the manipulation target and assembly target.

Innovation Solution

A robot system with a control device that uses visual servo control and compliant motion control, where the rotation center is determined based on captured images and force sensor data, allowing for precise rotation and translation of objects relative to each other, even when the rotation center position shifts due to external forces.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If the rotation center position is determined based on initial setup, then the control system is simple, but the assembly precision deteriorates when the rotation center shifts during work

Engineering Contradiction:
Improvecontrol system complexityVSAvoidassembly precision
Core Design Contradiction:
Device complexityVSManufacturing precision

Solution Approach 1:

The patent implements visual feedback by continuously capturing images of the manipulation target and hand, detecting their positions and postures, and using this information to update the rotation center position dynamically during assembly work. This feedback mechanism allows the system to adapt to position shifts while maintaining assembly precision without requiring complex mechanical structures.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The patent transitions from a static rotation center determination (based on initial setup) to a dynamic determination process where the rotation center is continuously updated based on real-time visual information. This dynamic approach enables the system to adapt to changes in the manipulation target's position and posture during assembly, resolving the contradiction between system simplicity and assembly precision.

Inventive Principle:
Principle #15Dynamics

2Manufacturing precision

If visual servo control is implemented to detect rotation center changes, then assembly precision is improved, but the device complexity increases

Engineering Contradiction:
Improveassembly precisionVSAvoidcontrol system complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent replaces complex mechanical sensing systems with a vision-based control system. By using an imaging device to capture images and computationally determine the rotation center position based on the manipulation target's posture, the system achieves high assembly precision without requiring complex mechanical sensors or actuators to detect position changes.

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

Solution Approach 2:

The patent creates a visual representation (image) of the physical system state and uses this copy to determine control parameters. By processing the captured image to extract the manipulation target's position and posture, the system indirectly detects rotation center changes without direct physical measurement, simplifying the overall system while maintaining precision.

Inventive Principle:
Principle #26Copying

3Ease of operation

If the rotation center is fixed relative to the gripping unit, then control is simple, but assembly quality deteriorates when the manipulation target rotates

Engineering Contradiction:
Improvecontrol simplicityVSAvoidassembly quality
Core Design Contradiction:
Ease of operationVSManufacturing precision

Solution Approach 1:

The patent makes the rotation center dynamic by continuously updating its position based on the manipulation target's current posture detected from images. Instead of fixing the rotation center relative to the gripping unit, the system recalculates it based on the target's actual position and orientation, ensuring accurate assembly even when the target rotates during the work process.

Inventive Principle:
Principle #15Dynamics

Data Source

PatentEP2915635B1Robot, robot system, control device, and control method
Publication Date: 2020.09.02 SEIKO EPSON CORP
  • EP2915635B1 patent drawingFigure 1
  • EP2915635B1 patent drawingFigure 2
  • EP2915635B1 patent drawingFigure 3~4

AI summary

Provided is a robot including a hand and a control unit that operates the hand. The control unit rotates a first object around a predetermined position of the first object with the hand and moves the first object with respect to a second object, based on a captured image including the hand and the first object. Therefore, the robot can perform good assembly work. The predetermined position may be a coordinate origin that moves with the first object, and the control unit may translate the first object in addition to rotating the first object. The robot may also include a force sensor that detects an external force acting on the hand.