Robot Screwdriver Coupling for Vibration-Resistant Force Control

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Solution Overview

Problem

Existing screwing devices coupled to robot arms face difficulties in accurately measuring and regulating the actuating force when screwing into a wall, particularly in environments with disturbance variables like concrete walls, where direct force measurement is challenging due to vibrations and impacts.

Innovation Solution

A screwing device with a connection element comprising a first and second transmission element, a restoring element, and a distance measuring element, allowing indirect measurement of the actuating force by measuring the distance between the transmission elements, which is resistant to shocks and vibrations, and can be used with various tools like screwdrivers, power drills, or grippers.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If direct force measurement is used (e.g., strain gauge), then force can be measured, but measurement precision deteriorates due to vibrations and impacts from screwing into concrete walls

Engineering Contradiction:

Improveforce measurement precisionVSAvoidvibrations and impacts

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent introduces a restoring element (spring) as an intermediary between the robot arm and the screwing tool. This spring element absorbs vibrations and impacts during screwing operations, isolating the force sensor from harmful mechanical disturbances. The spring acts as a buffer that decouples the high-frequency vibrations from the measurement system, enabling accurate force measurement even when screwing into concrete walls.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent replaces direct mechanical force measurement (strain gauge directly on the tool) with an indirect measurement approach using a restoring element and displacement sensing. Instead of measuring force directly at the tool interface where vibrations occur, the system measures the displacement of the restoring element and calculates force from this displacement, substituting a vibration-prone mechanical measurement with a more stable indirect measurement method.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Reliability

If a restoring element is introduced to enable indirect force measurement, then measurement reliability improves, but device complexity increases

Engineering Contradiction:

Improveforce measurement reliabilityVSAvoidconnection element structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The restoring element serves multiple functions simultaneously: it acts as a force transmission element, a vibration buffer, and a measurement transducer. By making the restoring element multi-functional, the patent avoids adding separate components for each function, thereby limiting the increase in device complexity while achieving reliable force measurement.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Object-affected harmful factors

If distance measurement is used to indirectly determine actuating force, then resistance to shocks and vibrations improves, but measurement precision requirements increase

Engineering Contradiction:

Improveresistance to shocks and vibrationsVSAvoiddistance measurement precision

Core Design Contradiction:

Object-affected harmful factorsVSMeasurement precision

Solution Approach 1:

The patent changes the measurement parameter from direct force measurement to displacement measurement. By measuring the displacement of the restoring element instead of force directly, the system becomes resistant to shocks and vibrations. The restoring element's mechanical properties (spring constant) are used to convert the displacement measurement into force information, filtering out high-frequency vibrations in the process.

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

Enables reliable and precise control of the actuating force, ensuring consistent screwing operations by using the measured distance to adjust the force within a desired range, reducing the risk of jamming and improving the efficiency of screwing processes.

Implementation Method 1

a restoring element arranged between the first and second transmission element, wherein the two transmission elements can be moved towards each other, in an actuation direction, against a restoring force of the restoring element

Methodology Applied

Scientific EffectElasticity: Elasticity

Data Source

PatentUS11559904B2Screwing device and method for screwing a screw into a wall

Publication Date: 2023.01.24 INVENTIO AG

AI summary

A screwing device includes a screwdriver and a connection element for coupling the screwdriver to a robot arm. The connection element has a first robot-side transmission element, a second tool-side transmission element, a restoring element arranged between the first and second transmission elements, and a distance measuring element. The two transmission elements can be moved towards each other against a restoring force of the restoring element in an actuation direction. The distance measuring element measures a distance that represents the spacing between the transmission elements in the actuation direction and is used to control the actuating force acting on the screwdriver.