Brush Cutter Safety Device Frequency-Based Acceleration Detection
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Solution Overview
Problem
Existing safety devices for handheld work apparatuses, such as brush cutters and chain saws, fail to automatically activate in situations where the worker loses control due to kickback, falls, or intentionally throws the device, as they require manual operation to engage the safety mechanism, and struggle to differentiate between normal vibration and abnormal shake indicative of unsafe conditions.
Innovation Solution
A safety device equipped with an acceleration sensor that classifies acceleration information into specific frequency ranges to detect abnormal conditions, using a filtering and amplification mechanism to identify peaks within a low-frequency range indicative of potential dangers, triggering a safety signal to stop the cutting tool.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If manual operation safety devices (stop levers, pressure sensors) are used, then the device complexity is reduced, but the reliability of safety protection deteriorates because the worker may not be able to release the handle during unexpected situations like kickback or falling
Solution Approach 1:
The patent replaces manual mechanical safety devices (stop levers, pressure sensors) with an automated sensor-based system. An acceleration sensor detects abnormal vibrations and shocks, while a control unit automatically processes the signals and triggers safety mechanisms, eliminating the need for manual operation and ensuring reliability during unexpected situations.
Solution Approach 2:
The safety system operates autonomously by detecting abnormal conditions through acceleration sensors and automatically activating safety measures without requiring worker intervention. The control unit continuously monitors sensor data and independently decides when to engage the brake mechanism or cut power, making the system self-protecting.
2Measurement precision
If acceleration sensor with frequency range classification is used, then the measurement precision of unsafe condition detection is improved, but the device complexity increases due to signal processing requirements
Solution Approach 1:
The control unit is pre-programmed with frequency range criteria that distinguish normal operation vibrations from unsafe condition shocks. The acceleration sensor data is continuously compared against these predetermined thresholds, allowing immediate recognition of dangerous conditions without complex real-time analysis.
Solution Approach 2:
The system implements continuous feedback by monitoring acceleration sensor output and automatically adjusting safety responses based on detected vibration patterns. The control unit processes sensor signals in real-time, comparing them against stored frequency ranges and triggering appropriate safety actions when abnormal patterns are detected.
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
The solution effectively differentiates between normal operation vibrations and abnormal conditions, allowing for automatic activation of the safety mechanism to prevent accidents by stopping the cutting tool when unsafe situations are detected, enhancing worker safety without relying on manual operation.
Implementation Method 1
an acceleration sensor provided in the work apparatus; an acceleration peak computation means supplied with acceleration information from the acceleration sensor and finding out a peak of acceleration included in the acceleration information
Data Source
AI summary
In a brush cutter (100), when it is determined based on acceleration information including frequency components, supplied from an acceleration sensor (24) included in the brush cutter (100) that the acceleration shows a peak in a range of frequencies lower than 100 Hz, the flow moves to step S5 to amplify the acceleration peak. In next step S6, the acceleration peak is compared with a threshold. When the result of comparison shows that the acceleration peak is higher than the threshold, the flow moves to step S7 to produce a safety signal. The safety signal is output from the controller (26) to a high voltage generation circuit (30) to stop generation of a high voltage in the high voltage generating circuit (30). In this manner, the acceleration sensor (24) is used to detect any unexpected, sudden danger, while diminishing influence of the acceleration caused by vibration inherent to the own nature of the work apparatus, its intended regular operation and its posture change in regular operation.