Handheld Power Tool Work-State Detection Using Motor Signals
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Solution Overview
Problem
Existing handheld power tools, such as rotary impact drivers, face challenges in automating screwing and unscrewing operations due to the inability to accurately determine work status, leading to potential overtightening or screws dropping, especially when dealing with different types of screws and materials, and require additional sensors which increase costs and complexity.
Innovation Solution
A method that determines the work status of a handheld power tool by analyzing operating variables like motor speed and current, using model signal shapes and threshold values to classify applications and automate reactions, such as speed adjustments or motor control, without the need for additional sensors, through a machine learning phase that learns from user interactions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If additional sensors (e.g., acceleration sensors) are used to determine operating mode, then measurement precision improves, but device complexity and cost increase
Solution Approach 1:
The system uses existing motor operating variables (speed, current) to self-determine the operating mode without requiring external sensors. The evaluation unit analyzes these self-generated signals to identify whether the tool is in impact operation or continuous rotation mode, making the system self-sufficient.
Solution Approach 2:
The patent replaces mechanical/sensor-based detection systems with an electronic evaluation system that processes motor operating variables. Instead of using acceleration sensors to detect mechanical vibrations, the system electronically evaluates motor current and speed patterns to determine operating mode.
2Ease of operation
If fixed limit values and threshold values are used for impact ascertainment, then ease of operation improves, but adaptability to different applications deteriorates
Solution Approach 1:
The system dynamically adapts the limit values and threshold values based on the detected application type. The evaluation unit adjusts these parameters in real-time according to whether the application is wood screwing, metal screwing, or drilling, ensuring optimal performance for each specific task while maintaining automatic operation.
Solution Approach 2:
The patent changes the operating parameters (limit values, threshold values) according to the detected application type. The system identifies the application category and automatically adjusts the evaluation criteria to match the specific requirements of wood screwing, metal screwing, or drilling operations.
3Manufacturing precision
If user manually monitors work status and reacts to changes, then manufacturing precision improves, but productivity deteriorates
Solution Approach 1:
The system continuously monitors motor operating variables and provides automatic feedback control. The evaluation unit detects changes in operating mode and triggers appropriate reactions (such as switching off the motor or adjusting speed) without requiring user intervention, maintaining precision while enabling continuous operation.
Solution Approach 2:
The tool performs self-monitoring and self-adjustment of operating parameters based on detected work status changes. The system automatically identifies when impact operation starts or stops and takes appropriate corrective actions, eliminating the need for manual user monitoring and reaction.
Data Source
AI summary
A method is for operating a hand-held power tool that includes an electric motor. The method includes determining a signal of an operating parameter of the electric motor; determining an application class at least partly on the basis of the signal of the operating parameter; and providing comparative information at least partly on the basis of the application class including (i) providing at least one model-signal form, and (ii) providing a threshold value for correspondence. The model-signal form can be assigned to an established state in the progress of the work performed by the hand-held power tool. The method further includes comparing the signal of the operating parameter with the model-signal form and determining a correspondence evaluation from the comparison. The correspondence evaluation is at least partly based on the threshold value for correspondence.