Inertial force sensor
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Solution Overview
Problem
Conventional inertial force sensors approximate temperature correction using a quadratic curve, limiting accuracy and requiring larger circuit sizes and increased computation for higher-degree corrections.
Innovation Solution
An inertial force sensor with a detection element, temperature sensor, bridge circuit, AD converter, calculation circuit, and storage that uses a calibration curve with coefficients for higher-degree corrections, allowing for quartic or sextic pseudo corrections without increasing circuit size or computation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a quadratic curve is used for temperature correction, then the circuit size and computation amount are reduced, but the measurement precision is limited
Solution Approach 1:
The patent replaces the conventional analog quadratic curve correction circuit with a digital correction system using an A/D converter, microcomputer, and software-based polynomial calculation. This substitution enables higher-degree correction (quartic or sextic) to be performed through digital computation rather than complex analog circuitry, achieving higher measurement precision without proportionally increasing circuit complexity.
Solution Approach 2:
The patent changes the correction method from fixed quadratic curve approximation to variable higher-degree polynomial correction. By using a microcomputer to calculate correction values based on temperature-dependent polynomial expressions (quartic or sextic), the system dynamically adjusts correction parameters according to temperature conditions, significantly improving measurement precision across the full temperature range.
2Measurement precision
If a quadratic curve is used for temperature correction, then the circuit structure is simplified, but the measurement precision is limited
Solution Approach 1:
The patent replaces the conventional analog quadratic curve correction circuit with a digital correction system using an A/D converter, microcomputer, and software-based polynomial calculation. This substitution enables higher-degree correction (quartic or sextic) to be performed through digital computation rather than complex analog circuitry, achieving higher measurement precision without proportionally increasing circuit complexity.
Solution Approach 2:
The patent introduces a microcomputer as an intermediary between the temperature sensor and the correction process. The microcomputer reads temperature data, calculates higher-degree correction values using polynomial expressions, and applies these corrections to the output signal. This intermediary enables complex correction mathematics to be performed without requiring equally complex analog circuit structures.
3Measurement precision
If higher-degree correction is implemented using conventional methods, then the measurement precision is improved, but the computation amount increases
Solution Approach 1:
The patent performs preliminary calculation of polynomial correction coefficients during the calibration phase and stores them in the microcomputer's memory. During normal operation, the system only needs to evaluate the pre-calculated polynomial expressions with the current temperature value, significantly reducing real-time computation requirements while maintaining high correction accuracy.
Solution Approach 2:
The patent replaces the conventional analog quadratic curve correction circuit with a digital correction system using an A/D converter, microcomputer, and software-based polynomial calculation. This substitution enables higher-degree correction (quartic or sextic) to be performed through digital computation rather than complex analog circuitry, achieving higher measurement precision without proportionally increasing circuit 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
Enables higher-degree correction of higher accuracy with a small circuit size and minimal computation, effectively addressing the limitations of conventional sensors.
Implementation Method 1
a temperature sensor that detects an ambient temperature of the detection element
Implementation Method 2
a bridge circuit that processes an output signal from the detection element
Implementation Method 3
an AD converter that converts an analog signal output from the bridge circuit into a digital signal
Data Source
AI summary
An inertial force sensor includes: an acceleration detection element; a temperature sensor that detects an ambient temperature of the acceleration detection element; a bridge circuit that processes an output signal from the acceleration detection element; an AD converter that converts an analog signal output from the bridge circuit into a digital signal, and outputs the digital signal; a calculation circuit that performs calculation on the output signal from the AD converter; and a storage that stores correction data for correcting a variation in the output signal from the AD converter due to a temperature change. The correction data are coefficients of a formula expressed by a calibration curve that is a quadratic or higher-degree curve, and the storage stores, as the correction data, the coefficients of the calibration curve of each of a plurality of patterns that differ between a predetermined temperature or more and less than the predetermined temperature.