Multi-Axis Robot Tool Head Positioning to Prevent Drilling Slippage

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Solution Overview

Problem

Existing multi-axis robots experience tool slippage during machining operations, leading to inaccuracies and potential damage to the workpiece due to imbalanced force distribution.

Innovation Solution

A method and device for controlling the tool head of a multi-axis robot using three strain sensors arranged in a triangular configuration to detect force imbalances and adjust the tool's position to prevent slippage, combined with a controller device to regulate bearing force and balance mechanical stresses.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If a multi-axis robot uses a tool-carrying head to carry out machining operations, then high positioning accuracy and precision are achieved, but tool slippage may occur on the workpiece surface leading to drilling errors

Engineering Contradiction:
Improvepositioning accuracyVSAvoidtool slippage risk
Core Design Contradiction:
Manufacturing precisionVSReliability

Solution Approach 1:

The patent applies preliminary action by detecting force imbalances on the workpiece surface before tool slippage occurs. The strain sensors continuously monitor bearing forces and detect imbalances that would lead to slippage, allowing the control system to take corrective action in advance to maintain reliable machining operations

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent implements feedback control by using strain sensors to continuously monitor the bearing forces between the tool head and workpiece surface. The control system processes sensor signals to detect force imbalances and adjusts the robot's positioning in real-time to maintain stable contact and prevent tool slippage, thereby resolving the contradiction between high positioning accuracy and preventing tool slippage

Inventive Principle:
Principle #23Feedback

2Manufacturing precision

If strain sensors are used to regulate the tool's bearing force on the workpiece surface, then high positioning accuracy is achieved, but force imbalance may cause tool slippage

Engineering Contradiction:
Improvepositioning accuracyVSAvoidforce imbalance
Core Design Contradiction:
Manufacturing precisionVSObject-generated harmful factors

Solution Approach 1:

The patent uses feedback control through strain sensors that continuously monitor bearing forces on the workpiece surface. The control system processes sensor signals to detect force imbalances and adjusts the robot's positioning in real-time to maintain balanced force distribution, thereby achieving high positioning accuracy while preventing tool slippage caused by force imbalance

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The patent applies parameter changes by dynamically adjusting the robot's position and bearing force based on real-time sensor feedback. The control system modifies positioning parameters to maintain optimal force distribution on the workpiece surface, resolving the contradiction between achieving high positioning accuracy and preventing force imbalance that causes tool slippage

Inventive Principle:
Principle #35Parameter changes

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

The method effectively reduces the risk of tool slippage by balancing forces, ensuring precise and accurate machining operations.

Implementation Method 1

each configured to deliver to a controller device information representative of stresses (forces) measured and applied in a direction parallel to its longitudinal axis

Methodology Applied
Scientific EffectStrain sensor measurement: Piezoresistive Effect

Data Source

PatentEP4575686A1Method for controlling the position of a tool head of a multi-axis robot and system for carrying out the method
Publication Date: 2025.06.25 AIRBUS OPERATIONS (SAS)
  • EP4575686A1 patent drawingFigure 1~2
  • EP4575686A1 patent drawingFigure 3~4a
  • EP4575686A1 patent drawingFigure 4b~5

AI summary

The invention relates to an improved method for controlling the position of a tool-holder head (1) of a multi-axis robot, in particular used for drilling operations of aeronautical equipment parts in a first direction (Z), the method operating a regulation of the bearing force of the tool on a part to be machined in this first direction (Z) while operating a servo-control of the position of the tool-holder head (1) in two other directions (X, Y) perpendicular to each other and each perpendicular to the first direction (Z), from information (Se1, Se2, Se3) representative of forces oriented in the first direction (Z) and obtained from three separate sensors (16a, 16b, 16c); the invention also relates to a controller device configured to execute the method of positioning said head (1).Thus, it is advantageously possible to improve the quality of machining operations carried out by the tool-carrying tool head, in particular by reducing or avoiding slippage of a tool on a part to be machined.