Contactless Pedal Position Sensing With Ambiguity-Free Magnetic Output
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Solution Overview
Problem
Current contactless pedal position determination systems in vehicles face limitations due to the periodicity of the magnetic field, requiring large magnets and increased costs, and must ensure precise and reliable position detection to meet high functional reliability standards, often necessitating redundant systems.
Innovation Solution
A device with a magnet and sensor that generates a varying magnetic field, where the sensor detects at least two spatial components and calculates gradients to produce a position signal and signal strength, allowing for a combination of these signals to generate an output signal that is either position-dependent or constant, depending on threshold values, thereby minimizing magnet size and avoiding ambiguity in position determination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a positioning magnet is used for contactless position detection, then the pedal position can be detected without contact, but the periodicity of the magnetic field limits the unambiguous position determination range
Solution Approach 1:
The patent transitions from one-dimensional position determination (limited by magnetic field periodicity) to two-dimensional determination by incorporating signal strength as an additional dimension. The signal strength, derived from the gradient magnitude, provides a monotonic relationship with position that resolves the ambiguity inherent in periodic magnetic field patterns alone.
2Measurement precision
If large magnets are used to enable continuous tracking of all positions, then unambiguous position determination over the full range is achieved, but the cost increases
Solution Approach 1:
The patent changes the parameter used for position determination from relying solely on magnetic field periodicity (which requires large magnets) to using signal strength derived from gradient magnitude. This parameter change enables accurate position determination across the full range with a compact magnet, as the signal strength provides a monotonic relationship with position.
3Reliability
If position-determining sensors are made robust against interference fields, then functional reliability of the braking system is ensured, but component and circuit board costs increase due to redundancy requirements
Solution Approach 1:
The patent introduces signal strength as an intermediary parameter that mediates between the magnetic field measurements and the final position determination. By using signal strength (gradient magnitude) as an additional discriminator, the system achieves robust position determination without requiring redundant sensor systems, thereby reducing complexity while maintaining reliability.
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 allows for precise and reliable contactless pedal position detection without the need for large magnets, reducing costs and ensuring accurate braking requests, while being robust against interference and maintaining high functional reliability.
Implementation Method 1
the magnet generates a magnetic field that changes with the position of the pedal, which can be detected by means of the sensor
Implementation Method 2
a position-determining sensor, such as a Hall sensor
Data Source
Figure 1~1a
Figure 2
Figure 3a~3d
AI summary
The invention relates to a device (1) for contactlessly determining a position of a pedal (2), in particular in a vehicle, which device comprises at least one magnet (3) and a sensor (4), wherein the magnet (3) generates a magnetic field (5) which can be changed by means of the position of the pedal (2) and which can be detected by means of the sensor (4), and the sensor (4) comprises an output (7) for providing at least one sensor signal (8), wherein: - the device (1) comprises a processing means (9); - the processing means (9) comprises inputs (10) for reading in the at least one sensor signal (8) and outputs (11) for outputting an output signal (12); - a first and a second position range (13, 14) is defined, wherein each position range (13, 14) comprises positions of the magnet (3) with respect to the sensor (4); - the processing means (9) generates an output signal (12) from the at least one sensor signal (8), wherein the output signal (12) in the first position range (13) assumes values which are clearly associated with a position of the magnet (3) relative to the sensor (4), and in the second position range (14) assumes a constant value which is independent of the position of the magnet (3) relative to the sensor (4).