Power Tool Touch Sensing for Two-Hand Activation Control
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Solution Overview
Problem
Existing power tools lack effective mechanisms to distinguish between a user's hand and other objects, leading to potential false activations and safety hazards due to factors like water, dirt, or debris, and do not ensure both hands are securely gripping the tool before operation.
Innovation Solution
Incorporation of impedance or capacitive touch sensors on multiple handles to detect the presence of a user's hands, with a controller ensuring both hands are detected before allowing tool operation, and distinguishing between human hands and inanimate objects based on impedance or capacitance changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If traditional activation mechanisms are used, then the tool can be activated easily, but false activations occur due to water, dirt, or debris
Solution Approach 1:
The patent replaces traditional mechanical activation mechanisms (triggers, switches) with capacitive touch sensors that detect the electrical properties of human skin. This substitution allows the system to distinguish between human hands and inanimate objects like water or dirt, which have different capacitance characteristics, thereby preventing false activations while maintaining ease of use.
Solution Approach 2:
The patent utilizes changes in electrical capacitance and impedance parameters when a human hand contacts the sensor surface. By monitoring these parameter changes and comparing them against predefined thresholds, the system can reliably detect human presence and differentiate it from environmental contaminants, resolving the contradiction between ease of activation and false activation resistance.
2Ease of operation
If no hand detection mechanism is used, then the tool can be operated freely, but safety hazards occur without proper hand grip
Solution Approach 1:
The patent implements preliminary hand detection through capacitive sensors before allowing tool operation. The system continuously monitors for the presence of human hands on designated grip areas before enabling activation, ensuring that users are properly positioned and aware of the tool's operation, thereby preventing safety hazards while maintaining operational freedom.
Solution Approach 2:
The patent employs feedback mechanisms where the capacitive sensors continuously provide information about hand presence to the control system. This real-time feedback allows the system to dynamically adjust operation permissions based on detected hand positions, ensuring safety requirements are met while preserving user freedom to operate the tool when conditions are appropriate.
3Ease of operation
If single hand detection is used, then the tool can be operated with one hand, but safety is reduced compared to two-hand operation
Solution Approach 1:
The patent divides the hand detection system into multiple independent capacitive sensor zones, each capable of detecting hand presence separately. This segmentation allows the system to require activation of multiple zones (corresponding to multiple hands) for full operation permission, providing enhanced safety control while still allowing flexible operation modes including one-hand operation when appropriate.
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 safety by preventing tool activation without proper hand grip and reducing false activations, ensuring secure and controlled operation.
Implementation Method 1
The second handle includes a touch sensor (e.g., a capacitive touch sensor, an inductive touch sensor). The touch sensor is configured to detect a second hand of the user on the second handle.
Implementation Method 2
the power tool includes one or more impedance sensors that can be used to detect when a user is gripping one or more handles or surfaces of the power tool
Data Source
Figure 1A
Figure 1B
Figure 1C
AI summary
Systems and methods for power tools having touch sensors. One power tool includes a housing (100), a motor (200), a first handle (110), a second handle (115), and a controller (300). 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.