Galvanically Isolated Electrodes for Proximity Detection
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Solution Overview
Problem
Existing proximity detection systems for cutting tools, such as circular saws, fail to reliably detect the approach of an operator's hand due to electrical coupling with the machine, leading to increased injury risk and false alarms when distinguishing between human presence and wooden objects.
Innovation Solution
A proximity detection system utilizing galvanically isolated electrodes and a logic control unit to generate and process electric field signals, determining the presence of an operator's limb by analyzing signal amplitudes and phases, with adjustable frequency signals to differentiate between human and wooden objects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the blade and ground plane are used to define a capacitance for proximity detection, then the detection system can be implemented, but the machine frame acts as a receiver and the operator's body (high dielectric constant) causes capacitance increase making reliable detection difficult
Solution Approach 1:
The patent extracts the detection function from the machine frame by using galvanically isolated electrodes. The first electrode is connected to the machine frame while the second electrode is galvanically isolated from it, allowing the detection of hand approach without the frame acting as a receiver that would be affected by the operator's body capacitance.
Solution Approach 2:
The patent introduces galvanically isolated electrodes as intermediaries between the machine frame and the detection function. These electrodes serve as mediators that can detect the operator's hand approach through capacitance changes without being electrically coupled to the frame, thus avoiding the interference caused by the operator's body capacitance.
2Measurement precision
If a capacitance-based detection system is used, then proximity detection is possible, but the system cannot distinguish between the operator's hand and wooden objects, causing false alarms
Solution Approach 1:
The patent changes the electrical parameters (impedance, capacitance, conductance) measured by the galvanically isolated electrodes to differentiate between human hands and wooden objects. By analyzing multiple electrical parameters simultaneously, the system can identify the unique electrical characteristics of human tissue versus wood, reducing false alarms while maintaining detection precision.
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
Precisely detects the approach of an operator's limb, reducing injury risk and avoiding false alarms by effectively distinguishing between human presence and wooden objects, enhancing operational safety and machine reliability.
Implementation Method 1
wherein said signal S G (t) generated by said at least one signal generator is configured to generate an electric field between said at least one first electrode and said at least one second electrode
Implementation Method 2
The blade and the ground plane, therefore, define a capacitance having a respective dielectric constant
Implementation Method 3
The blade and the ground plane, therefore, define a capacitance having a respective dielectric constant
Data Source
Figure 1~2
Figure 3~4A
Figure 4B~5
AI summary
The present invention relates to a machine (M) for working products, such as panels made of wood, fiberglass, metal and the like, comprising a working tool (22) for working said products, wherein said machine (M) is characterized in that it comprises a system (1) for detecting the proximity of a limb of an operator to said working tool (22), comprising: at least one signal generator (G), for generating at least one signal SG(t); at least one first electrode (10), galvanically isolated from said machine (M) and connected to said at least one signals generator (G); at least a second electrode (11) galvanically isolated from said machine (M), wherein said signal SG(t) generated by said at least one signal generator (G) is configured to generate an electric field between said at least one first electrode (10) and said at least one second electrode (11); wherein said electric field between said at least one first (10) and said at least one second electrode (11) forms a barrier at least partially around said working tool (22); and a logic control unit (12) connected to said at least one first electrode (10), and to said at least second electrode (11), so as to acquire at least one first measuring signal SE10(t) from said at least one first electrode (10) and at least one second measuring signal SE11(t) from said at least one second electrode (11) respectively; wherein said logic control unit (12) is configured for processing said at least one first SE10(t) and at least one second SE11(t) measuring signal, for verifying at least one criterion as a function of at least two electrical quantities of said first SE10(t) and second SE11(t) measuring signal, so as to determine the presence of said limb of said operator in proximity of said barrier when said at least one criterion is verified. The present invention also relates to a proximity detection system for machining tools. The present invention related also to a method of proximity detection.