RF Signal Strength Proximity Verification for Power Tool Control

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Solution Overview

Problem

In factory settings, assembly line workers often inadvertently exchange power tools, leading to incorrect tool settings being used due to the lack of effective identification and tracking systems, especially in wireless-controlled environments where tools can be easily misplaced.

Innovation Solution

A portable power tool system utilizing short-range wireless RF transceivers, where a processor-controlled logic circuit assesses signal strength to determine proximity to a fixed controller, enabling or disabling the tool based on predefined thresholds, thereby ensuring correct tool usage within designated work areas.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If wireless control is used without umbilical cords, then ease of operation is improved, but reliability deteriorates due to tool swapping and incorrect settings

Engineering Contradiction:
Improveease of operationVSAvoidreliability
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The system continuously monitors RF signal strength between the tool and controller to determine proximity. When the tool moves outside the designated work area or is picked up by another worker, the signal strength changes, triggering automatic disabling of the tool. This feedback mechanism ensures the tool can only be operated when at the correct workstation, preventing tool swapping while maintaining wireless operation.

Inventive Principle:
Principle #23Feedback

2Reliability

If factory-wide tool identification and tracking systems are implemented, then reliability is improved, but device complexity and cost increase

Engineering Contradiction:
ImprovereliabilityVSAvoiddevice complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The invention extracts the essential function of tool tracking from a complex factory-wide system and implements it locally using simple RF transceivers already present in wireless tools. By taking out only the proximity verification function and implementing it through signal strength monitoring, the system achieves reliable tool identification without the complexity and cost of comprehensive tracking infrastructure.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The tool itself performs the identification and verification functions using its own RF transceiver and the controller's transceiver. Each tool automatically determines its own location and operational status based on RF signal strength, eliminating the need for external tracking systems to monitor and manage tool positions centrally.

Inventive Principle:
Principle #25Self-service

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

Prevents unintentional tool swapping by ensuring the tool is only enabled when within its designated area, allowing for precise job execution and reducing errors related to incorrect torque settings or tool configurations.

Implementation Method 1

a first radio frequency transceiver configured to propagate a digital communication signal... a second radio frequency transceiver configured to communicate with the first radio frequency transceiver and providing a signal strength datum indicative of the received signal strength

Methodology Applied
Scientific EffectRadio frequency signal propagation: Electromagnetic Induction

Data Source

PatentEP3400492B1Power tool system having in-station verification utilizing radio frequency signal strength
Publication Date: 2020.10.07 NEWFREY LLC
  • EP3400492B1 patent drawingFigure 1
  • EP3400492B1 patent drawingFigure 2~3
  • EP3400492B1 patent drawingFigure 4

AI summary

The industrial power tool system includes a controller physically disposed in a predefined location within an assembly line work station. The controller has a first radio frequency transceiver that propagates a digital communication signal at a predefined power. A human operable portable power tool has a second radio frequency transceiver configured to communicate with the first transceiver, providing a signal strength datum indicative of the received signal strength. A processor circuit causes the tool to perform a sequence of predefined assembly job steps that are mediated by the processor circuit according to a control loop running on the processor circuit. The processor circuit compares the signal strength datum to a predefined signal strength threshold to determine if the distance between the first and second radio frequency transceivers is less than a predefined distance that defines a home area proximate the controller. The processor circuit uses the test of this distance as at least one operative step in the control loop that mediates the sequence of predefined assembly job steps.