Hand-Held Power Tool Work Progress Detection From Motor Signals
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Solution Overview
Problem
Existing hand-held power tools, such as percussive screwdrivers, require high user concentration to manage machine characteristics like start and end of percussive mechanisms, leading to potential over-tightening or dropping of screws due to inadequate reaction times, and existing solutions with additional sensors are costly and complex.
Innovation Solution
A method that analyzes operational variables like motor speed using model signal waveforms to detect work progress independently, eliminating the need for user adjustments and additional sensors, allowing for automatic motor responses based on detected work progress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If percussive screwdrivers are used to automate screwing operations, then productivity is improved, but reliability deteriorates due to user inability to react quickly enough to machine characteristics
Solution Approach 1:
The control unit continuously monitors operational variables (motor speed, current) and uses this feedback to automatically detect work progress and trigger appropriate motor responses, eliminating the need for user reaction and ensuring consistent quality
Solution Approach 2:
The system performs self-monitoring and self-adjustment by automatically detecting work progress through operational variable analysis and autonomously controlling motor responses, making the system independent of user intervention
2Measurement precision
If additional sensors like accelerometers are installed to detect work progress, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The solution extracts and utilizes operational variable signals (motor speed, current) that are already generated by the motor during normal operation, eliminating the need for additional sensors while maintaining work progress detection capability
Solution Approach 2:
The motor serves multiple functions: it provides the driving force for the percussive mechanism and simultaneously acts as a sensor source through its operational variables, which contain information about work progress without requiring separate sensing components
3Ease of operation
If fixed limit values and thresholds are used for percussive detection, then ease of operation is improved, but adaptability deteriorates because the same thresholds cannot work for different applications
Solution Approach 1:
The system dynamically adapts detection thresholds based on the specific application by analyzing operational variable patterns and automatically adjusting the match evaluation criteria, allowing the same system to work across different screw types and materials without manual reconfiguration
Solution Approach 2:
The control unit changes detection parameters (thresholds, match criteria) based on the analyzed operational variable patterns specific to each work progress, enabling automatic adaptation to different applications while maintaining ease of operation
Data Source
AI summary
A method for operating a hand-held power tool is disclosed, with the hand-held power tool including an electric motor. The method includes step (S1) providing comparative information, having the steps of (S1a) providing at least one model signal waveform, said model signal waveform being assignable to the work progress of the hand-held power tool, and (S1b) providing a threshold of a match. The method further includes step (S2) ascertaining a signal of an operational variable of the electric motor. The method also includes step (S3) analyzing the comparative information and the signal of an operational variable, having the steps of (S3a) comparing the signal of the operational variable with the model signal waveform and ascertaining a match signal from the comparison, and (S3b) ascertaining a match evaluation, said match evaluation being carried out at least partly using the threshold of the match and using the match signal. In addition, the method includes step (S4) detecting the work progress at least partly using the match evaluation ascertained in step S3, said comparative information being provided at least partly on the basis of an automatic evaluation of the match signal. An associated hand-held power tool is also disclosed.