Robot TCP Supervision With Hose-Like Tolerance Zones

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Solution Overview

Problem

The existing methods for supervising robots result in a significant reduction of their operational workspace due to the need for a large buffer zone around the safety zone, as they require a long follow-on distance to stop, which can extend into the safety zone, posing a risk to persons in the working range.

Innovation Solution

Defining a hose-like tolerance zone along the movement path that is outside the safety zone, with its width being anti-proportional to the desired movement speed, allowing for continuous verification of the actual Tool Center Point (TCP) position within this zone, and initiating an immediate stop if it exceeds the tolerance zone limits.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a safety zone with buffer zone is used to ensure robot safety, then safety is improved, but the operational workspace is reduced

Engineering Contradiction:
ImprovesafetyVSAvoidoperational workspace
Core Design Contradiction:
ReliabilityVSArea of stationary object

Solution Approach 1:

The system performs preliminary verification of the robot's actual position against the tolerance zone before the robot completes its movement. By continuously verifying position data and detecting deviations early, the system can initiate stopping actions before the robot enters the safety zone, eliminating the need for a large buffer zone and preserving operational workspace while maintaining safety.

Inventive Principle:
Principle #10Preliminary action

2Reliability

If a large buffer zone is created around the safety zone, then safety is improved, but the follow-on distance increases

Engineering Contradiction:
ImprovesafetyVSAvoidfollow-on distance
Core Design Contradiction:
ReliabilityVSLength of moving object

Solution Approach 1:

The system continuously verifies the robot's actual position against the programmed movement path and tolerance zone, creating a feedback loop. When a deviation is detected, the system provides feedback to initiate a stop command. This real-time feedback mechanism allows for early detection and immediate response, reducing the follow-on distance required to stop the robot while maintaining safety.

Inventive Principle:
Principle #23Feedback

3Reliability

If the robot movement is stopped immediately upon exceeding tolerance zone, then safety is improved, but the response time requirement increases

Engineering Contradiction:
ImprovesafetyVSAvoidresponse time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The system performs preliminary verification of position data continuously during robot movement, rather than waiting for the robot to complete its motion or enter a buffer zone. By detecting deviations early and initiating stop commands immediately upon exceeding the tolerance zone, the system minimizes the response time required while maintaining safety.

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentEP2900432B1Method for supervising a robot
Publication Date: 2021.02.24 ABB (SCHWEIZ) AG
  • EP2900432B1 patent drawingFigure 1~2
  • EP2900432B1 patent drawingFigure 3

AI summary

The invention is related to a method for supervising a robot (12, 62) having a robot controller (14) which is foreseen to control a movement of the robot (12, 62) according to data of a predefined movement program, comprising the following steps: providing a movement program defining at least a given movement path (22, 42, 64) for a tool center point (TCP) of the robot (12, 62), defining a tolerance zone (24, 52, 66) around the movement path (22, 42, 64), moving the robot (12, 62) with its TCP running along the movement path (22, 42, 64) according to the movement program, continuously determining the actual position of the TCP, continuously verifying whether the actual TCP position is within the tolerance zone (24, 52, 66), stopping of the robot movement in the case that the actual TCP is outside (46) the tolerance zone (24, 52, 66). The tolerance zone (24, 52, 66) is extending in a hose-like manner along the movement path (22, 42, 64).