Laser Sensor Angle Control for Precise Robot Seam Tracking

Resolve Bottlenecks,
Find Innovative Solutions
Generate Solutions

Solution Overview

Problem

Existing robot control systems face challenges in maintaining precision during seam tracking operations, particularly when dealing with curved operation lines with large curvature, as the field of view of laser sensors is limited, leading to decreased precision and potential exit of the operation line from the sensor's field of view.

Innovation Solution

A robot control apparatus that adjusts the angle about the tool axis to keep the operation line at the center of the laser sensor's field of view, utilizing feedback control with integral and differential actions to maintain trackability, especially when curvature changes, preventing the operation line from exiting the field of view and enhancing precision.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the angle γ at the tool position is controlled to maintain a predetermined value during tracking operation, then the field of view can be positioned to follow the curved operation line, but the operation line exits the field of view when curvature is large and precision decreases near the field of view edges

Engineering Contradiction:
Improveadaptability to curved operation linesVSAvoiddetection precision of operation line position
Core Design Contradiction:
Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

Instead of controlling the angle γ at the tool position to follow the curved operation line, the invention inverts the approach by controlling the angle between the laser sensor's optical axis and the operation line to be a predetermined value. This ensures the operation line remains within the field of view while maintaining detection precision, as the laser sensor's field of view is positioned to cover the operation line rather than having the operation line follow the field of view edge.

Inventive Principle:
Principle #13The other way round (Inversion)

2Ease of operation

If the field of view is positioned at the outer side of the curve during tracking operation, then the angle control can maintain a predetermined value, but the operation line may exit the field of view when curvature is large

Engineering Contradiction:
Improveease of angle controlVSAvoidcontinuity of seam tracking operation
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The invention implements feedback control by continuously adjusting the angle between the laser sensor's optical axis and the operation line based on real-time detection. The control unit calculates the curvature of the operation line and dynamically adjusts the angle to keep the operation line within the field of view, ensuring continuous and reliable seam tracking operation even when curvature changes.

Inventive Principle:
Principle #23Feedback

3Measurement precision

If feedback control is used to set the operation line at the center of the field of view, then trackability improves for curved operation lines, but sudden angle adjustments may cause mechanical issues

Engineering Contradiction:
Improvetrackability of feedback controlVSAvoidmechanical problems from sudden angle adjustment
Core Design Contradiction:
Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The invention applies dynamic control by adjusting the angle between the laser sensor's optical axis and the operation line based on real-time curvature detection. The control unit calculates the required angle adjustment and implements it progressively, adapting to changing curvature conditions while preventing sudden mechanical movements that could cause problems.

Inventive Principle:
Principle #15Dynamics

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

This approach ensures precise seam tracking by maintaining the operation line within the highest precision area of the laser sensor's field of view, even with large curvature, and prevents sudden angle adjustments that could cause mechanical issues.

Implementation Method 1

a laser sensor 5 that detects a shape of a working target 6

Methodology Applied
Scientific EffectLaser: Laser

Implementation Method 2

the field of view of a laser sensor is a range in which shapes can be detected by the laser sensor (sensing range)

Methodology Applied
Scientific EffectLight reflection: Reflection

Data Source

PatentEP3760358B1Robot control apparatus with a laser sensor and an angle adjusting control unit, and robot control system with such apparatus
Publication Date: 2022.05.04 DAIHEN CORP
  • EP3760358B1 patent drawingFigure 1
  • EP3760358B1 patent drawingFigure 2
  • EP3760358B1 patent drawingFigure 3

AI summary

In order to provide a robot control apparatus that can realize a more precise seam tracking operation, a robot control apparatus (1) includes: a storage unit (11), in which teaching data is stored; an accepting unit (12) that accepts a sensing result of a laser sensor (5), from a robot (2) including a working tool (4) and the laser sensor (5) attached to the working tool (4) and configured to detect a shape of a working target before an operation of the working tool (4); and a control unit (14) that moves the working tool (4) based on the teaching data, corrects the movement of the working tool (4) based on the sensing result, and adjusts an angle about a tool axis such that an operation point indicated by the sensing result is at a center of a field of view of the laser sensor (5). Accordingly, an operation line can be detected near the center of the field of view of the laser sensor (5), and thus more precise detection is possible. As a result, the level of precision of the seam tracking operation is improved.