Contactless Pedal Position Sensing With Segmented Magnetic Range
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Solution Overview
Problem
Existing contactless pedal position detection systems in vehicles face limitations due to the periodicity of the magnetic field, leading to ambiguous position determination and increased costs associated with large magnets, while requiring precise and reliable braking demand transmission.
Innovation Solution
A device comprising a magnet and a sensor with a processor that generates output signals based on sensor inputs, defining two position ranges where the signal is unambiguous in the first range and constant in the second, using magnetic field gradients to determine position and signal strength, and employing threshold detection to compensate for ambiguity without additional components or larger magnets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a periodic magnetic field is used for contactless pedal position detection, then the position can be determined without contact, but the position determination becomes ambiguous beyond a limited range
Solution Approach 1:
The measurement range is segmented into a first position range where unambiguous position determination is required and a second position range where maximum braking demand is sufficient. The output signal is segmented to provide unambiguous values in the first range and a constant maximum value in the second range, resolving the contradiction by applying different signal characteristics to different operational zones.
Solution Approach 2:
The output signal parameter changes from position-dependent values in the first position range to a constant maximum value in the second position range. This parameter change allows the system to maintain precision where needed while extending the effective range by saturating the output at maximum braking demand, thereby resolving the limitation of periodic magnetic field detection.
2Adaptability or versatility
If large magnets are used to detect all positions continuously, then the detectable position range increases, but the manufacturing costs increase
Solution Approach 1:
Instead of providing continuous unambiguous position determination across the entire range (excessive action), the system provides precise determination only in the first position range where it is actually needed for braking control. In the second range, a constant maximum signal is sufficient, reducing the requirements for magnet size and complexity while maintaining full functionality.
Solution Approach 2:
The invention uses standard permanent magnets with typical dimensions rather than large or complex magnet arrangements. By accepting that unambiguous determination is not needed beyond the first position range, the system can use cost-effective, off-the-shelf magnet components, significantly reducing manufacturing costs.
3Reliability
If position-determining sensors are made redundant to ensure functional safety, then the reliability improves, but the component and circuit board costs increase
Solution Approach 1:
The processor acts as an intermediary that implements threshold-based logic to distinguish between the first and second position ranges. This software-based differentiation eliminates the need for redundant sensor systems, maintaining functional safety through intelligent signal interpretation rather than hardware redundancy.
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 unambiguous position determination within a limited range while minimizing magnet size, ensuring precise braking demand transmission and reducing costs by using permanent magnets and gradient-based signal processing, resistant to interfering fields.
Implementation Method 1
the magnet produces a magnetic field that varies with the position of the pedal and that can be detected by means of the sensor
Implementation Method 2
a position-indicating magnet and a position-determining sensor, for example a Hall sensor
Data Source
AI summary
A device for contactlessly determining a position of a pedal in a vehicle, having at least a magnet and a sensor, wherein the magnet produces a magnetic field that varies with the position of the pedal and detected by the sensor. The sensor has an output for providing at least one sensor signal. A first and a second position range are defined, wherein each position range includes positions of the magnet with respect to the sensor. The processor generates an output signal from the at least one sensor signal. The output signal takes on values that are unambiguously associated with a position of the magnet relative to the sensor in the first position range, and takes on a constant value that is independent of the position of the magnet relative to the sensor in the second position range.