Position Sensor Threshold Memory for Actuator Miscounting
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Solution Overview
Problem
Current magnetic field sensors for determining the position of motor-driven objects in rotating magnetic fields often miscount due to predefined threshold settings that do not account for the last crossed threshold, leading to inaccurate position determination.
Innovation Solution
A position sensor system that stores and retrieves the information about the last crossed threshold using a memory element, allowing it to adjust the threshold settings upon activation, thereby preventing miscounting even when the sensor is unpowered or partially powered.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a predefined threshold is used for the comparator circuit, then the device complexity is reduced, but miscounting occurs during the activation phase leading to poor measurement precision
Solution Approach 1:
The system performs preliminary action by storing information about the last crossed threshold before entering inactive mode, and restoring this information upon activation. This preliminary preparation ensures that the comparator circuit can correctly determine positions during the activation phase without miscounting, resolving the contradiction between simple predefined thresholds and accurate measurement.
2Use of energy by moving object
If the position sensor is put into inactive mode to save energy, then the use of energy is reduced, but the information about the last crossed threshold is lost causing miscounting
Solution Approach 1:
Before entering inactive mode, the system performs preliminary action by storing the last crossed threshold information in a memory element. Upon activation, this stored information is restored to the comparator circuit, preventing information loss and miscounting while still allowing the sensor to enter low-power inactive mode.
Solution Approach 2:
A memory element is introduced as an intermediary between the comparator circuit and the inactive mode state. This intermediary stores the critical threshold information when power is reduced, acting as a bridge that preserves information across power states and enables accurate position determination upon reactivation.
3Measurement precision
If extra hardware is added to set the initial output to prevent miscounting, then the measurement precision is improved, but the device complexity increases
Solution Approach 1:
The memory element serves multiple functions: it stores the last crossed threshold information, maintains this information during inactive modes, and restores it upon activation. This multi-functional approach prevents miscounting without requiring separate initialization hardware, achieving high measurement precision while minimizing device complexity.
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
The system ensures accurate position determination of motor-driven objects by avoiding miscounting errors, maintaining accuracy even during inactive modes, and reducing hardware and processing complexity.
Implementation Method 1
at least one sensing element adapted to transduce a time-varying external signal into at least one first electrical signal
Implementation Method 2
at least one comparator circuit adapted to perform a thresholding operation on the at least one first electrical signal being characterized by a hysteresis curve having a high threshold and a low threshold
Data Source
AI summary
A position sensor for determining the position of an object, comprising at least one sensing element to transduce a time-varying external signal into an electrical signal; at least one comparator circuit adapted to perform a thresholding operation on the electrical signal being characterized by a hysteresis curve; the position sensor is adapted to provide information relating to the last crossed to store it at least while the position sensor is in an inactive mode and to restore the information to obtain a selected threshold when it is switched from inactive to active mode; and configured such that a transition in an output signal is generated by the thresholding operation if the selected threshold is crossed by the electrical signal and configured to change the selected threshold after it was crossed by the electrical signal.