Adaptive Kickback Detection for Sensor-Based Power Tools

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Solution Overview

Problem

Power tools, such as saws and milling cutters, experience kickback events due to sudden and unexpected forces during machining, leading to safety concerns and operational inefficiencies, particularly when used by inexperienced users or with varying workpiece properties.

Innovation Solution

A power tool with a sensor device that detects mechanical quantities like force, acceleration, velocity, deflection, and deformation, and a control device that selectively chooses between different recognition functions based on user experience and environmental conditions to optimize kickback detection, allowing for tailored sensitivity in recognizing kickback events.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a single recognition function with fixed sensitivity is used for kickback detection, then the device complexity is reduced, but the adaptability to different user skill levels and workpiece conditions deteriorates

Engineering Contradiction:
Improveadaptability to user skill level and workpiece conditionsVSAvoidcomplexity of control device with multiple recognition functions
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The control device dynamically selects between multiple recognition functions based on detected operating conditions and user skill level. The system transitions between different detection sensitivities and algorithms in real-time, making the kickback detection adaptive rather than static. This resolves the contradiction by allowing the system to have multiple functions available while only activating the appropriate one based on current conditions.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The system changes parameters of the recognition function based on detected conditions. Different recognition functions have different sensitivity thresholds, time constants, and detection algorithms. The control device adjusts which function is active based on workpiece material, tool type, and user skill level, allowing optimal detection without requiring all functions to be simultaneously complex.

Inventive Principle:
Principle #35Parameter changes

2Measurement precision

If a sensitive recognition function is used for kickback detection, then the measurement precision of kickback events is improved, but the productivity deteriorates due to unnecessary interruptions

Engineering Contradiction:
Improveprecision of kickback detectionVSAvoidmachining productivity due to interruptions
Core Design Contradiction:
Measurement precisionVSProductivity

Solution Approach 1:

The system applies different recognition functions with different sensitivity levels appropriate to local conditions. For experienced users or stable workpiece conditions, a less sensitive function is used that tolerates more variation without triggering interruptions. For inexperienced users or unstable conditions, a more sensitive function provides higher precision detection. This local adaptation of detection quality resolves the contradiction between precision and productivity.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The recognition function dynamically adapts its sensitivity based on detected operating conditions. The system monitors workpiece material, tool wear, and user behavior to adjust detection thresholds in real-time. This dynamic adjustment allows the system to maintain high precision when needed while reducing false positives that would cause unnecessary interruptions and productivity loss.

Inventive Principle:
Principle #15Dynamics

3Productivity

If an insensitive recognition function is used for kickback detection, then the productivity is maintained by avoiding unnecessary interruptions, but the reliability of safety detection deteriorates

Engineering Contradiction:
Improvemachining productivityVSAvoidreliability of kickback detection
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The system applies appropriately sensitive recognition functions based on local conditions and user skill level. For inexperienced users, a more sensitive function ensures high reliability of detection even if it causes more interruptions. For experienced users, a less sensitive function maintains productivity while still providing reliable detection of actual kickback events. This local adaptation resolves the contradiction between productivity and reliability.

Inventive Principle:
Principle #3Local quality

4Adaptability or versatility

If multiple recognition functions are available for kickback detection, then the adaptability to different conditions is improved, but the device complexity increases

Engineering Contradiction:
Improveversatility of recognition functionsVSAvoidcomplexity of control device
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The control device uses dynamic selection logic to choose between multiple recognition functions based on detected conditions. Rather than implementing all functions simultaneously with equal complexity, the system uses conditional logic to activate only the appropriate function for current conditions. This dynamic approach provides versatility while managing complexity through selective activation rather than simultaneous implementation.

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

Enhances the usability of power tools by providing appropriate sensitivity for kickback detection, reducing unnecessary interruptions and improving safety by adapting recognition functions to the user's skill level and workpiece conditions.

Implementation Method 1

a sensor device (2) for detecting a mechanical quantity (3), the mechanical quantity comprising a force, an acceleration, a velocity, a deflection, a deformation and/or a mechanical stress

Methodology Applied
Scientific EffectForce detection: Force

Data Source

PatentUS11701723B2Power tool, system, and method
Publication Date: 2023.07.18 FESTOOL GMBH
  • US11701723B2 patent drawing
  • US11701723B2 patent drawing
  • US11701723B2 patent drawing

AI summary

A power tool with a rotatable tool designed as a saw blade or a milling cutter, including a sensor device for detecting a mechanical quantity, the mechanical quantity having a force, an acceleration, a velocity, a deflection, a deformation and/or a mechanical stress, and the mechanical quantity being dependent on a force emanating from the tool, and a control device communicatively coupled to the sensor device, which control device is adapted to recognize a kickback event based on the detected mechanical quantity, where the control device is adapted to selectively determine a first recognition function or a second recognition function different from the first recognition function based on a function determination information, and to perform the recognition of the kickback event based on the detected mechanical quantity using the determined recognition function.