Dual-Arm Robot Teaching Using Backdrive and Tip Guidance

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Solution Overview

Problem

Conventional direct teaching of dual-arm robots is cumbersome and requires exclusive sensors, leading to delays and safety concerns, especially when performing rapid operations, and is complicated due to the need to avoid arm interference.

Innovation Solution

A teaching system where the teacher grips both arm tips with hands to move the arms directly, eliminating the need for exclusive sensors by turning off servo motors and disengaging brakes, using backdrive for easier movement and incorporating self-weight compensation mechanisms to reduce load and enhance safety.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If exclusive sensors such as joystick and force sensor are used for direct teaching, then the robot can be taught operations, but a delay occurs in robot operation during teaching and a sense of discomfort is felt

Engineering Contradiction:
Improvedirect teaching operationVSAvoiddelay in robot operation
Core Design Contradiction:
Ease of operationVSLoss of time

Solution Approach 1:

The patent removes exclusive teaching sensors (joystick, force sensor) from the system and uses only the robot's existing drive system. The teacher directly operates the arm tip end without intermediate sensing devices, eliminating the delay caused by sensor processing and signal transmission.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The control device acts as an intermediary that monitors the teacher's direct operations and controls the servo motors accordingly. This allows direct manual operation while maintaining automated control through the servo system, avoiding delays associated with dedicated teaching sensors.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Productivity

If rapid operation is inputted during direct teaching, then teaching efficiency increases, but the robot may perform abrupt change operation causing danger

Engineering Contradiction:
Improveteaching efficiencyVSAvoidsafety of robot operation
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The control device continuously monitors the teacher's operations and provides feedback control through the servo motors. This feedback mechanism detects rapid or abrupt operations and can adjust the robot's response to prevent dangerous movements while maintaining teaching efficiency.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The servo motors provide dynamic control that adapts to the teacher's input speed. The system can handle rapid operations when safe, but automatically adjusts to prevent abrupt changes that would cause danger, making the system both efficient and safe.

Inventive Principle:
Principle #15Dynamics

3Reliability

If teaching of dual-arm robot is performed by finding routes that avoid interferences between two arms, then the robot can operate safely, but the teaching process becomes complicated

Engineering Contradiction:
Improvesafety of dual-arm operationVSAvoidcomplexity of teaching process
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The dual-arm robot system allows the teacher to directly manipulate both arms simultaneously without pre-programmed interference avoidance routines. The control device handles collision detection and route adjustment automatically, making the safety mechanisms self-activating rather than requiring complex teaching procedures.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The patent replaces complex mechanical teaching procedures for avoiding arm interference with an automated control system that uses sensors and algorithms to detect and prevent collisions between arms during teaching operations.

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

4Ease of operation

If servo motors are turned off and brakes are disengaged to enable backdrive for easier arm movement, then teaching operation becomes easier, but the possibility of robot going out of control increases

Engineering Contradiction:
Improveease of arm movementVSAvoidcontrol stability
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The control device provides continuous feedback control even when servo motors are in backdrive mode. This feedback mechanism monitors arm position and velocity, ensuring that the robot remains controllable during teaching operations despite the servo motors being turned off and brakes disengaged.

Inventive Principle:
Principle #23Feedback

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 intuitive and easy teaching of dual-arm robots without the need for additional sensors, ensuring safety and reducing the complexity of avoiding arm interference, thus making the teaching process more efficient and cost-effective.

Implementation Method 1

a self-weight compensation mechanism configured to come the second link to rest with respect to the first link by applying a force in the opposite direction of gravity to the second link

Methodology Applied
Scientific EffectSelf-weight compensation: Gravitation

Implementation Method 2

the control device may acquire the teaching points in a state where the servo motors are turned off and brakes are disengaged... by using the backdrive of each arm, the teacher becomes easier to move both the arms

Methodology Applied
Scientific EffectBackdrive: Friction

Data Source

PatentEP3238888B1Dual arm robot teaching system and dual arm robot teaching method
Publication Date: 2023.03.08 KAWASAKI JUKOGYO KK
  • EP3238888B1 patent drawingFigure 1
  • EP3238888B1 patent drawingFigure 2
  • EP3238888B1 patent drawingFigure 3

AI summary

The purpose is to perform a teaching work of a dual-arm robot instinctively and easily. A teaching system (1) of a dual-arm robot according to the present disclosure includes a dual-arm robot (2) including two arms (4R, 4L) comprised of a plurality of links coupled to each other with joint shafts, and two instructing parts (5R, 5L) provided to tip ends of the two arms, respectively, and configured to indicate coordinate points in space and to be grippable by a teacher, and a control device (3) configured to acquire the coordinate points indicated by the teacher moving the two instructing parts directly and simultaneously with both hands as teaching points, and teach the dual-arm robot operation corresponding to the acquired teaching points.