Wireless Rotating Force-Torque Measurement for Machining

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Solution Overview

Problem

Current systems for measuring force and torque during machining are limited by the need for a stator unit and connection cable, which increase setup time and costs, and do not provide sufficient accuracy or uninterrupted operation.

Innovation Solution

A system that wirelessly transmits measurement data directly from a rotor unit to an evaluation unit, eliminating the stator unit and connection cable, and uses low-power transmission to enable extended operation without interruption, with enhanced 16-bit resolution and adjustable data transfer rates for improved accuracy and efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a stator unit and connecting cable are used to transmit measurement data, then power supply and data transmission are reliable, but setup time increases and system complexity increases

Engineering Contradiction:
Improvepower supply reliabilityVSAvoidsetup time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The patent extracts and eliminates the stator unit and connecting cable from the measurement system. The rotor unit now contains all necessary components (measuring unit, energy storage unit, control unit with wireless transmitter) to operate independently without external power supply or data transmission cables, thereby reducing setup time and system complexity while maintaining operational reliability

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent replaces the mechanical/electrical connection system (connecting cables and stator unit) with a wireless transmission system. The control unit transmits measurement data wirelessly to external receivers, eliminating the need for physical cable connections and reducing setup complexity while maintaining data transmission reliability

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Reliability

If transmission power is increased for wireless data transmission, then data transmission reliability improves, but energy consumption increases reducing operating time

Engineering Contradiction:
Improvedata transmission reliabilityVSAvoidenergy consumption
Core Design Contradiction:
ReliabilityVSUse of energy by moving object

Solution Approach 1:

The control unit transmits measurement data in periodic intervals rather than continuously. This periodic transmission approach maintains data transmission reliability by regularly updating measurement values while significantly reducing overall energy consumption compared to continuous high-power transmission, enabling extended operating times of at least 8 hours

Inventive Principle:
Principle #19Periodic action

Solution Approach 2:

The system dynamically adjusts transmission parameters including power level and data transfer rate based on operational requirements. By optimizing these parameters, the system achieves reliable data transmission at minimal energy consumption, extending the operating time of the energy storage unit

Inventive Principle:
Principle #35Parameter changes

3Measurement precision

If measurement resolution is increased to 16 bits, then measurement accuracy improves, but data transmission requirements and energy consumption increase

Engineering Contradiction:
Improveforce and torque measurement accuracyVSAvoidenergy consumption
Core Design Contradiction:
Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The system uses 16-bit resolution for local measurement and processing to ensure high accuracy, but transmits only essential or processed data wirelessly rather than all raw measurement data. This approach maintains measurement precision while reducing the energy burden of wireless transmission

Inventive Principle:
Principle #16Partial or excessive action

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 solution allows for high-accuracy, real-time measurement of force and torque with reduced energy consumption, enabling uninterrupted operation for at least 8 hours and reducing setup complexities, thus enhancing machining efficiency and cost-effectiveness.

Implementation Method 1

The 4-component dynamometer type 9170A uses piezoelectric transducers, which generate measured values in the form of electrical polarization charges under the influence of the force and torque components

Methodology Applied
Scientific EffectPiezoelectric effect: Piezoelectric Effect

Implementation Method 2

The stator unit wirelessly supplies the rotor unit with electrical energy via the air gap

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentEP4134198A1System for machining a workpiece and for measuring and evaluating force and torque during the machining of the workpiece
Publication Date: 2023.02.15 KISTLER HLDG AG
  • EP4134198A1 patent drawingFigure 1
  • EP4134198A1 patent drawingFigure 2
  • EP4134198A1 patent drawingFigure 3

AI summary

The invention relates to a system (100) for machining a workpiece (0) and for measuring and evaluating force and torque during the machining of the workpiece (0); which system (100) comprises a machine tool (1) for machining the workpiece (0) with a tool (11), a device (2) for measuring force and torque during the machining of the workpiece (0), and an evaluation unit (3) for evaluating measurement data (MD) from the device (2); which device (2) is installed in the machine tool (1) and rotates about a rotary axis (Z) during machining with the tool (12); which evaluation unit (3) is stationary; which device (2) comprises a measuring unit (22) which generates measurement values ​​(P) under the component types (Fx, Fy, Fz, Mz) of force and torque acting during machining;which device (2) has a control unit (23) which control unit (23) wirelessly transmits the measured values ​​(P) as measured value data (MD) directly to the evaluation unit (3); wherein the wireless transmission of the measured value data (MD) takes place with a transmit power (L) in the range of 0.1mW to 10mW.;