Two-Handle Touch Sensing for Power Tool False-Start Prevention
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Solution Overview
Problem
Existing power tools often experience false activations due to liquids, dirt, or debris, and lack effective user presence detection, leading to safety and operational issues.
Innovation Solution
Incorporating impedance or capacitive touch sensors to detect a user's hands on multiple handles of a power tool, with a controller that distinguishes between human presence and inanimate objects, ensuring motor operation only when both hands are correctly positioned.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional activation sensors are used in power tools, then the device can be activated, but false activations occur due to liquids, dirt, or debris
Solution Approach 1:
The patent replaces traditional mechanical or simple electrical contact sensors with impedance sensors that detect the electrical properties of the user's hand. These impedance sensors measure parameters such as resistance, capacitance, or impedance changes when a human hand contacts the sensor surface, distinguishing human tissue properties from liquids, dirt, or debris which have different electrical characteristics. This substitution eliminates false activations while maintaining reliable user presence detection.
2Reliability
If user presence detection is added to power tools, then safety is improved, but device complexity increases
Solution Approach 1:
The patent integrates impedance sensing capability into existing handle surfaces or grip areas of the power tool, allowing these components to serve dual functions: maintaining their primary structural and ergonomic roles while simultaneously acting as sensors for user presence detection. This multi-functionality approach adds safety capabilities without requiring entirely separate sensor systems, thereby limiting the increase in device complexity.
Solution Approach 2:
The patent combines the impedance sensing function with the existing handle structure and control system of the power tool. The sensor elements are integrated into the handle surfaces, and the control system processes impedance signals alongside other operational parameters. This merging approach consolidates multiple functions into unified components, adding safety features while minimizing overall system complexity.
3Reliability
If multiple hand detection is required for operation, then accident prevention is improved, but ease of operation is reduced
Solution Approach 1:
The patent requires the user to establish proper grip on both handles before the power tool can be activated. The control system detects user presence on both handles through impedance sensors and only permits motor operation when both hands are correctly positioned. This preliminary verification of proper gripping ensures safety by preventing accidental activation or single-handed operation, while the automated detection process minimizes the user's cognitive burden.
Solution Approach 2:
The patent implements real-time feedback through the impedance sensors that continuously monitor hand presence on both handles. The control system provides immediate feedback by enabling or disabling motor operation based on whether both hands are detected. This automated feedback loop ensures safety requirements are met while simplifying the user's task, as the system automatically manages the complexity of multi-hand detection rather than requiring manual verification.
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 user safety by preventing false starts and ensuring proper operation, reducing the risk of accidents and improving tool control.
Implementation Method 1
the touch sensor is an impedance sensor including: a surface; a transmitter configured to provide a load sine wave to the surface; and a receiver configured to receive a current response of the load sine wave
Implementation Method 2
the touch sensor is a capacitive sensor
Data Source
AI summary
Systems and methods for power tools having touch sensors. One power tool includes a housing, a motor, a first handle, a second handle, and a controller. The first handle includes a user input configured to be actuated by a first hand of a user. The second handle includes a touch sensor configured to detect a second hand of the user on the second handle. The controller is configured to determine whether the user input is actuated, determine whether the second hand of the user is on the second handle, control, in response to both the user input being actuated and the second hand of the user being on the second handle, the motor to drive the motor, and prohibit, in response to the user input being actuated and the second hand of the user not being on the second handle, operation of the motor.