Fluid Control Sensor Offset Learning for Response Time
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Solution Overview
Problem
Aging or manufacturing tolerances in position sensors of fluid control devices, such as variable geometry turbochargers, cause offsets in their characteristic curves, leading to reduced response times in control systems due to deviations from nominal characteristics.
Innovation Solution
A learning method for position sensors that calculates offsets at defined positions and applies these to estimate an updated characteristic curve, allowing for interpolation and curve-fitting to adjust for sensor drift, thereby maintaining system performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a position sensor is used in a fluid control device, then the operating position can be detected and control can be performed, but the sensor accuracy decreases over time due to ageing and manufacturing tolerances causing offsets in the characteristic curve
Solution Approach 1:
The control system performs preliminary calibration actions during engine startup or idle periods to establish the actual characteristic curve of the position sensor before normal operation begins. This preliminary characterization of the sensor's actual behavior compensates for ageing effects and manufacturing tolerances, ensuring accurate control response times from the start of operation
Solution Approach 2:
The system continuously monitors the position sensor output and compares it against the stored actual characteristic curve. Based on this feedback, the control unit applies real-time compensation to maintain accurate position detection despite sensor drift over time, thereby preserving both reliability and response time
2Ease of operation
If the sensor characteristic curve deviates from nominal due to offset, then the sensor can still provide position information, but the control system response time increases and performance decreases
Solution Approach 1:
The system changes the parameters used for control by storing not just the nominal characteristic curve but also the actual measured curve in memory. The control unit dynamically selects and applies the appropriate characteristic data based on operating conditions, transforming the raw sensor output into accurate position information even when the sensor exhibits offset or slope variations
Solution Approach 2:
The control system dynamically adapts to sensor characteristic changes by continuously updating or selecting between different characteristic curves based on operating conditions. This dynamic adaptation allows the system to maintain optimal response times across varying operational states despite sensor drift
Data Source
AI summary
A control method is provided for a fluid control device, particularly for an internal combustion engine, equipped with a position sensor having a nominal characteristic curve representative of a predetermined relationship between an admissible range of position values and a corresponding range of return electric signal values. The method includes, but is not limited to determining an offset (offsetopen; offsetclose) between a returned signal related to at least one defined position of the device and an expected signal related to the defined position of the device according to the nominal characteristic curve, estimating an updated characteristic curve of the sensor by applying the offset (offsetopen; offsetclose) to the nominal characteristic curve, and applying a predetermined control strategy of the fluid control device according to the updated characteristic curve.