Torque Signal Filtering for Rotary Impact Tools
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Solution Overview
Problem
Rotary impact tools face challenges in accurately measuring torque due to noise components in torque value signals, making it difficult to control the drive apparatus effectively.
Innovation Solution
A signal processing apparatus with a filter that adjusts its cutoff frequency based on the number of impacts and user settings, using a calculation circuit with machine learning to filter out noise components from the torque value signal, ensuring accurate torque measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a torque sensor is used to measure torque in a rotary impact tool, then torque measurement capability is provided, but noise components from impacts reduce measurement precision
Solution Approach 1:
A low-pass filter is introduced as an intermediary between the torque sensor and the control system. The filter has a cutoff frequency set to pass frequencies up to twice the impact frequency while attenuating higher frequency noise components. This intermediary component separates the useful torque signal from the harmful impact noise, resolving the contradiction between providing torque measurement capability and eliminating noise interference.
Solution Approach 2:
The cutoff frequency parameter of the low-pass filter is specifically set to twice the impact frequency, creating a dynamic threshold that adapts to the impact characteristics. This parameter change allows the filter to preserve the torque signal while systematically removing noise components above the threshold frequency, thereby improving measurement precision without losing essential torque information.
2Adaptability or versatility
If impact frequency varies during operation, then adaptability to different fastening stages is improved, but fixed filter settings reduce measurement accuracy
Solution Approach 1:
The filter cutoff frequency is made dynamic rather than fixed, allowing it to adapt to varying impact frequencies during different fastening stages. The filter automatically adjusts its characteristics based on the current impact frequency, ensuring optimal torque measurement accuracy whether the tool is operating during initial fastening, mid-range tightening, or final torque application stages.
Data Source
AI summary
A signal processing apparatus for a tool including a rotating body rotated by impacts delivered from a drive apparatus is provided with: a filter a calculation circuit and a control circuit. The filter receives a torque value signal indicating a torque applied to the rotating body, and filters the torque value signal. The calculation circuit sets a filter coefficient of the filter based on a number of impacts delivered to the rotating body. The control circuit controls the impacts delivered to the rotating body, based on the torque value signal filtered by the filter.