Coordinated Robot Control for Gripping Misalignment Correction

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Solution Overview

Problem

In coordinated control of multiple robots in a production line, existing systems face challenges in accurately maintaining the positional relationship between robots due to independent correction of gripping misalignments, leading to potential damage from excess force and deviation of workpieces during collaborative operations.

Innovation Solution

A robot system with a leading and following robot, equipped with detection and correction sections to quantify and adjust both the leading and following robots' position/orientation deviations, ensuring precise alignment and maintaining the intended positional relationship between workpieces during coordinated control.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If each robot independently corrects gripping misalignment, then gripping precision is improved, but the positional relationship between robots changes causing coordinated control errors

Engineering Contradiction:

Improvegripping precisionVSAvoidcoordinated control accuracy

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

The patent merges the correction operations of multiple robots into a unified coordinated correction process. Instead of each robot correcting independently, the system integrates the correction commands so that all robots adjust their positions simultaneously while maintaining their relative positional relationships, thus preserving both gripping precision and coordinated control accuracy

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The system implements feedback mechanisms to monitor the positional relationships between robots during correction operations. By continuously detecting the actual positions and comparing them with the taught positional relationships, the system can adjust correction commands in real-time to ensure that gripping precision is improved without compromising coordinated control accuracy

Inventive Principle:

Principle #23Feedback

2Manufacturing precision

If coordinated control is taught with fixed positional relationships, then collaborative operation accuracy is improved, but positional deviations accumulate causing operation errors

Engineering Contradiction:

Improvecollaborative operation accuracyVSAvoidpositional deviation detection

Core Design Contradiction:

Manufacturing precisionVSMeasurement precision

Solution Approach 1:

The patent applies preliminary action by pre-teaching the ideal positional relationships between robots during the programming phase. These taught positional relationships serve as reference data that the system uses to detect and correct deviations during actual operation, allowing the system to maintain high collaborative operation accuracy while compensating for accumulated positional deviations

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system uses feedback to continuously detect actual positional deviations from the taught relationships and automatically correct them. By comparing real-time position data with the pre-teached reference data, the system can identify deviations and apply corrective commands to maintain accurate collaborative operation

Inventive Principle:

Principle #23Feedback

3Manufacturing precision

If robot positions are corrected without coordination, then individual robot precision is improved, but excess force is applied causing workpiece damage

Engineering Contradiction:

Improveindividual robot precisionVSAvoidworkpiece damage from excess force

Core Design Contradiction:

Manufacturing precisionVSObject-affected harmful factors

Solution Approach 1:

The patent combines the correction operations of multiple robots into a coordinated action where correction commands are generated and applied simultaneously to all robots. This ensures that when robots adjust their positions to improve individual precision, they do so in a manner that maintains proper force distribution and prevents excess force from being applied to the workpiece

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The system applies preliminary anti-action by pre-calculating coordinated correction commands that compensate for potential force imbalances before they occur. By anticipating the effects of individual robot corrections on the overall system, the controller can adjust the correction commands to prevent excess force from being applied to the workpiece

Inventive Principle:

Principle #9Preliminary anti-action

Data Source

PatentUS10456917B2Robot system including a plurality of robots, robot controller and robot control method

Publication Date: 2019.10.29 FANUC LTD

AI summary

A robot system, a robot controller and a robot control method, by which a coordinated control of a plurality of robots can be taught while appropriately considering a positional deviation of each robot into consideration. A gripping misalignment of a first workpiece in a leading robot is detected, and then a first amount of correction for correcting the misalignment is calculated. Further, a gripping misalignment of a second workpiece in a following robot is detected, and then a second amount of correction for correcting the misalignment is calculated. In the coordinated control, a taught position/orientation of the leading robot is corrected based on the first amount of correction, and a taught position/orientation of the following robot is corrected based on both the first mount of correction and the second amount of correction.