Calibrated PWM Sensor Assembly Without Complex D/A Conversion
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Solution Overview
Problem
Existing sensor arrangements for detecting physical variables like temperature and humidity face issues with measurement accuracy due to component fluctuations, leading to varying output signals across different sensors, despite measuring the same variable, which affects precision and requires complex circuitry for high-resolution conversions.
Innovation Solution
A sensor arrangement with a digital signal processing unit that converts raw sensor signals into pulse-width-modulated output signals using arrangement-specific correction parameters stored in a memory unit, minimizing circuit complexity by eliminating the need for complex D/A converters and allowing flexible setting of the pulse duty factor relationship with measured variables.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If complex D/A converters are used to convert digital correction parameters into analog signals for high-precision PWM output, then measurement precision is improved, but device complexity increases considerably
Solution Approach 1:
The patent replaces complex analog D/A converter circuitry with a digital signal processing approach. The microcontroller unit generates PWM signals directly through digital processing of correction parameters, eliminating the need for complex analog-to-digital conversion hardware. This substitution of mechanical/electrical analog systems with digital processing resolves the contradiction by maintaining precision while reducing circuit complexity.
Solution Approach 2:
The patent changes the operational parameters by working entirely in the digital domain. Instead of converting digital correction parameters to analog signals via D/A converters, the system processes and outputs PWM signals directly in digital form. This parameter change from analog to digital operation eliminates the need for complex conversion circuitry while preserving measurement precision.
2Measurement precision
If analog signal processing components are used to generate PWM signals with correction variables, then measurement accuracy can be maintained, but the circuit complexity increases
Solution Approach 1:
The patent substitutes analog signal processing components with a microcontroller-based digital processing system. The microcontroller reads correction parameters from memory, processes sensor signals digitally, and generates PWM outputs without requiring complex analog operational amplifiers, filters, and other analog circuitry. This substitution maintains measurement accuracy while significantly reducing circuit complexity.
Solution Approach 2:
The microcontroller unit serves multiple functions: it stores correction parameters, processes raw sensor signals, applies corrections digitally, and generates PWM output signals. This multi-functional digital component replaces multiple specialized analog components, achieving the same measurement accuracy with reduced overall circuit complexity.
Data Source
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AI summary
A sensor arrangement comprises at least one sensor that detects variable physical quantities and provides a raw sensor signal as an output. Furthermore, a digital signal processing unit is provided for preprocessing the raw sensor signal into a sensor signal. The signal processing unit then converts at least one sensor signal into a pulse-width modulated (PWM) output signal with a duty cycle that depends on the measured quantity. In a memory unit, several arrangement-specific correction parameters are stored during a calibration cycle prior to measurement. The signal processing unit uses these parameters during measurement to convert the sensor signal into the PWM output signal. An amplifier unit then converts the PWM output signal into an analog voltage or current signal (Fig. 1).