Capacitive Position Sensor Interference Elimination
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Capacitive position measuring sensors face challenges in achieving high accuracy due to reduced capacitance with miniaturization, leading to increased interference in measurement signals, which complicates precise position determination.
Innovation Solution
Incorporating a capacitive reference measuring sensor alongside the position measuring sensor, using a computing unit to evaluate and eliminate interference signals by subtracting them from the position measurement signal, and employing materials with low thermal expansion for stable reference signals, along with integrated transistors for signal amplification to enhance accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If capacitive measuring sensors are miniaturized to reduce size, then the sensor dimensions are reduced, but the capacitance decreases leading to increased interference in measurement signals
Solution Approach 1:
A reference measuring sensor is introduced as an intermediary element to detect interference signals. This reference sensor does not measure the object's position directly but instead captures environmental interference (temperature changes, humidity, cable effects) that affects both the position measuring sensor and the reference sensor equally. By comparing the reference signal with the position measurement signal, the interference can be identified and eliminated, thereby maintaining measurement accuracy despite miniaturization.
Solution Approach 2:
The system implements feedback by continuously monitoring the reference measurement signal and using it to correct the position measurement signal. The computing unit processes both signals and uses the reference signal as feedback to identify and compensate for interference effects, ensuring that miniaturized sensors maintain their measurement precision despite reduced capacitance.
2Measurement precision
If a reference measuring sensor is added to eliminate interference, then measurement accuracy is improved, but device complexity increases
Solution Approach 1:
The reference measuring sensor serves multiple functions: it detects environmental interference, provides a reference signal for comparison, and enables compensation of cable effects and temperature variations. By making this single component multi-functional, the system achieves high measurement accuracy without proportionally increasing overall complexity.
Solution Approach 2:
The evaluation of position measurement and reference measurement is combined in a single computing unit that processes both signals simultaneously. This merging of evaluation functions allows the system to eliminate interference through signal comparison while avoiding the need for separate complex processing systems, thereby maintaining reasonable device complexity.
3Ease of operation
If signal cables are used to connect sensors, then signal transmission is enabled, but interfering influences and capacitance changes are introduced
Solution Approach 1:
The system converts the harmful effect of cable-induced interference into a beneficial measurement capability. By using the reference measuring sensor to detect the same cable interference that affects the position sensor, the system transforms the previously harmful cable effects into a detectable reference signal. This reference signal is then used to compensate and eliminate the interference from the position measurement, effectively converting cable-induced errors into a useful correction mechanism.
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 significantly improves measurement accuracy by isolating and eliminating interference, ensuring precise position determination with reduced noise and maintaining stability across varying conditions, particularly in the nanometer range.
Implementation Method 1
capacitive position measuring sensor (7) which provides to a computing unit (8) a position measurement signal (PM) relating to the object (3) to be measured
Implementation Method 2
capacitive reference measuring sensor (14) which provides to the computing unit (8) a reference measurement signal (RM)
Implementation Method 3
the at least one capacitive position measuring sensor (7) and/or the at least one capacitive reference measuring sensor (14) are embodied with an integrated transistor (28)
Implementation Method 4
the carrier body (21) is formed, in particular, from a material with a low coefficient of thermal expansion
Data Source
AI summary
In a position measuring device (5) and a method for ascertaining positions of an object (3) to be measured, at least one capacitive position measuring sensor (7) provides a position measurement signal (PM) relating to the object (3) to be measured and at least one capacitive reference measurement sensor (14) provides a reference measurement signal (RM). The measuring sensors (7, 14) are connected to a computing unit (8) which is embodied to calculate a position signal (P) to ascertain the positions from the position measurement signal (PM) and the reference measurement signal (RM). As a result of interfering influences being contained substantially equally in the position measurement signal (PM) and the reference measurement signal (RM) as an interference signal (S), it is possible to determine and eliminate the interference signal (S) during the calculation.