Hand-Held Tool Capacitive Sensing for Interference-Robust Activation
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Solution Overview
Problem
Existing hand-held machine tools with capacitive sensors are prone to faulty detections due to environmental disturbances and interference, leading to unreliable operation.
Innovation Solution
The method involves using at least two capacitive sensor elements with individually adjustable thresholds based on environmental conditions and interference levels, and a control unit to ensure reliable detection of a user's presence, enabling the actuation of the drive unit only when both sensors exceed their respective thresholds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a capacitive sensor is used to detect user presence, then the machine tool can be operated, but faulty detections occur due to environmental disturbances
Solution Approach 1:
The patent applies local quality by assigning different threshold values to different sensor elements based on their specific environmental conditions. Each sensor element has its threshold individually adapted to its location - for example, sensors near the drive unit or metallic objects use higher thresholds to avoid false detections from interference, while sensors in less disturbed areas use lower thresholds for sensitivity.
Solution Approach 2:
The patent implements parameter changes by dynamically adjusting the threshold parameter for each sensor element according to environmental factors. The control device modifies the threshold values based on detected interference levels, making the detection system adaptive to changing conditions rather than using fixed thresholds for all sensors.
2Reliability
If multiple capacitive sensor elements are used, then detection reliability can be improved, but device complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the detection system into multiple independent sensor elements, each responsible for a specific detection area. This segmentation allows each sensor to be optimized independently with its own threshold value, improving overall reliability while keeping the control logic manageable through modular evaluation of each sensor's output.
3Reliability
If higher threshold values are used for sensors in disturbed areas, then false detections are reduced, but sensitivity decreases
Solution Approach 1:
The patent resolves this contradiction by applying local quality - each sensor element's threshold is tailored to its specific location and environmental conditions. Sensors in high-interference areas use higher thresholds to reject false signals, while sensors in low-interference areas use lower thresholds to maintain high sensitivity, thereby optimizing both reliability and precision locally across the system.
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
This approach significantly reduces the risk of false detections by adapting threshold values to the specific environmental conditions, ensuring reliable and safe operation of the hand-held machine tool.
Implementation Method 1
at least two capacitive sensor elements operatively connected to the control device are provided
Data Source
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AI summary
The invention relates to a method for operating a hand-held machine tool (1) comprising a drive device (4), a control device (8) for actuating the drive device (4), and at least two capacitive sensor elements (30, 31, 32, 33) that are operatively connected to the control device (8). The method is characterized by the following steps: - ascertaining first and second electrical charges of the first and second sensor elements (30, 31, 32, 33); - comparing the ascertained first electrical charge with a defined first threshold value and the ascertained second electrical charge with a defined second threshold value that differs from the first threshold value; - enabling the actuation of the drive device (4) by the control device (8) when the first electrical charge is greater than the defined first threshold value and/or and the second electrical charge is greater than the defined second threshold value. Also described is a machine tool (1) for carrying out a method of this kind.