Outer Loop Torque Control for Multi-Axis Materials Testing

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Solution Overview

Problem

Existing materials testing systems are limited in their ability to apply multiple forces across orthogonal axes and degrees of freedom, particularly in controlling torque during complex deformation phenomena, such as upper and lower yield, and are not suitable for multi-axis or multi-degree of freedom testing.

Innovation Solution

A materials testing device equipped with multiple motors and a software-controlled outer loop system that uses a torque cell for feedback to apply and control torsional forces, allowing for the expansion of single-axis machines to multi-axis capabilities.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a single force (axial force) is used to impart stress in materials testing, then the testing system remains simple and single-axis, but the system cannot apply multiple forces across orthogonal axes or control torque during complex deformation phenomena

Engineering Contradiction:
Improvecapability to apply multiple forces across orthogonal axesVSAvoidsystem complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The existing single-axis testing machine is enhanced with an outer loop control system that enables multi-axis force application and torque control. The system maintains compatibility with original single-axis functionality while adding the capability to apply forces across multiple orthogonal axes, making the device universal for both simple and complex material testing scenarios

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The system transitions from single-axis (one-dimensional) force application to multi-axis (multi-dimensional) force application by introducing an outer loop control layer. This additional control dimension enables torque control and orthogonal force application without fundamentally redesigning the mechanical structure, effectively adding dimensional capability through software control

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Adaptability or versatility

If strain pacing is used to control straining rate, then the straining rate can be controlled for monotonic tests, but the system is not suitable for controlling straining rate during transient effects or multi-axis testing

Engineering Contradiction:
Improvesuitability for complex deformation testingVSAvoidcontrol accuracy during transient effects
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

The outer loop control system implements feedback mechanisms that continuously monitor system state and adjust control parameters in real-time. This feedback approach enables accurate control during transient effects and multi-axis operations, where simple strain pacing algorithms fail to maintain control accuracy

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The control system transitions from static strain pacing algorithms to dynamic control that adapts to changing test conditions. The outer loop continuously adjusts control parameters based on current system state, enabling reliable control during transient effects, yield phenomena, and multi-axis operations where conditions change rapidly

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

Enables the application of multiple forces across orthogonal axes, effectively controlling torque and strain rates, making it suitable for testing materials with complex deformation characteristics, including those exhibiting upper and lower yield phenomena.

Implementation Method 1

using the torque cell as a feedback device

Methodology Applied
Scientific EffectForce measurement: Force

Implementation Method 2

A torsion motor or driver is controlled by a torsion motor controller

Methodology Applied
Scientific EffectElectromagnetic conversion: Electromagnetic Induction

Data Source

PatentEP3867621B1Outer loop torque control
Publication Date: 2023.09.06 ILLINOIS TOOL WORKS INC
  • EP3867621B1 patent drawingFigure 1
  • EP3867621B1 patent drawingFigure 2

AI summary

The present disclosure relates to a materials testing device wherein an algorithmic approach is used to implement outer loop control software algorithm for control of a plurality of motors imparting different forces on a materials testing specimen. In particular, a torsion motor is controlled by an outer loop control software to control the rotational force applied to the materials testing sample.