Inductive Resonant Sensing for Metallic Actuator Position Detection
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Solution Overview
Problem
Existing actuation systems in motor vehicles face challenges in reliably detecting changes in the position of metallic actuating elements, such as door handles, while maintaining economic efficiency.
Innovation Solution
An actuation arrangement using an inductive sensor assembly with a coil and capacitor forming a parallel resonant circuit, coupled to a microcontroller, which monitors voltage drops across the resonant circuit and a parallel branch to detect changes in position by measuring the time interval between threshold voltage exceedances, allowing for high-speed and economical detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If inductive sensor arrays are used to detect position changes of metallic actuating elements, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The sensor arrangement is segmented into a resonant circuit (coil and capacitor) and a separate evaluation unit (microcontroller), allowing the sensing function to be distributed and simplified while maintaining high measurement precision through dedicated signal processing
Solution Approach 2:
The patent uses electromagnetic resonance (analogous to mechanical vibration) by creating a resonant circuit that oscillates at a specific frequency. The metallic actuating element disrupts this resonance, and the evaluation unit detects changes in resonance frequency or amplitude, providing precise position detection through resonant behavior
2Measurement precision
If inductive sensor arrays are used for position detection, then measurement precision is improved, but energy consumption increases
Solution Approach 1:
The resonant circuit is excited periodically rather than continuously, with the microcontroller triggering measurements only when needed. This periodic excitation maintains the ability to detect position changes with high precision while significantly reducing average energy consumption compared to continuous sensing operations
Solution Approach 2:
The system recovers energy by allowing the resonant circuit to naturally oscillate and decay after excitation, using the ring-down period for measurement without requiring continuous power input. This approach maximizes measurement precision during the active oscillation phase while minimizing energy consumption during idle periods
3Productivity
If a resonant circuit with parallel branch is used, then detection speed is improved, but device complexity increases
Solution Approach 1:
The parallel branch acts as an intermediary element that modifies the circuit's response characteristics. By adding a resistive or capacitive branch in parallel with the resonant circuit, the system achieves faster settling time and improved detection speed, while the microcontroller handles the complexity of evaluating the modified circuit response
4Ease of manufacture
If the sensor arrangement is made economically manufacturable, then ease of manufacture is improved, but measurement precision may deteriorate
Solution Approach 1:
The patent employs standard, commercially available components (off-the-shelf coils, capacitors, and microcontrollers) that can be easily manufactured and replaced. This approach prioritizes ease of manufacture and economic viability, while the precision of position detection is maintained through the robust resonant sensing principle and software-based evaluation algorithms rather than requiring expensive precision components
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
Enables reliable and efficient detection of position changes in metallic actuating elements, reducing energy consumption and enabling differentiated responses to varying actuation forces, suitable for vehicle door handles and hatches.
Implementation Method 1
The sensor assembly has all the necessary elements to generate a magnetic field, more precisely an electromagnetic field
Implementation Method 2
The underlying physical effect is the change in inductance and/or the quality factor of the inductance as a result of a change in the position of the conductive and/or ferromagnetic element
Implementation Method 3
the capacitor and the coil form part of an electrical resonant circuit of the actuating arrangement
Data Source
Figure 1a~2
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Figure 4
AI summary
The invention relates to an actuation arrangement of a motor vehicle with an inductive sensor arrangement. A first output of a microcontroller excites a resonant circuit with an excitation voltage (13). After a threshold exceedance of a start voltage (UStart) is detected at a first monitored voltage (14) and a threshold exceedance of a predetermined stop voltage (UStopp) is detected at a second monitored voltage (15), the time period (Δt) elapsed since the start time is determined. The invention also relates to a method for detecting a change in position.