Inertial Sensor Drive Frequency Tracking for Accurate Compensation
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Solution Overview
Problem
Existing inertial sensors face inaccuracies in temperature compensation due to decoupled temperature sensors, leading to indirect and inaccurate measurement of oscillation frequency changes.
Innovation Solution
The system uses a reference clock generator from an evaluation unit to directly measure the oscillation frequency of the inertial sensor, allowing for accurate compensation of frequency changes by determining the output data rate or providing a reference clock signal for internal correction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a physical temperature sensor integrated on the ASIC is used for temperature measurement, then temperature compensation can be performed, but temperature differences between the ASIC and MEMS occur due to decoupling via adhesive, leading to inaccurate compensation
Solution Approach 1:
The patent uses the output data rate of the inertial sensor as an intermediary parameter to indirectly determine oscillation frequency changes. Instead of directly measuring temperature with a decoupled sensor, the system measures the effect of temperature on the oscillator through the output data rate, which reflects the actual oscillation frequency of the MEMS device.
Solution Approach 2:
The patent replaces the mechanical/physical temperature sensor measurement system with an electronic measurement system that uses the output data rate of the inertial sensor. By substituting direct temperature measurement with frequency-based measurement through the output data rate, the system achieves more accurate tracking of actual MEMS oscillator frequency changes.
2Adaptability or versatility
If the oscillation frequency is determined indirectly through temperature measurement, then temperature compensation is possible, but the measurement of oscillation frequency changes becomes inaccurate
Solution Approach 1:
The patent implements a feedback mechanism where the output data rate of the inertial sensor is continuously monitored and used to determine oscillation frequency changes. This feedback loop allows the system to automatically adjust and compensate for frequency deviations in real-time, improving measurement precision while maintaining temperature compensation capability.
Solution Approach 2:
The inertial sensor itself provides the information needed for frequency measurement through its output data rate. The sensor's own operational characteristics are used to monitor its own frequency changes, eliminating the need for separate measurement systems and improving accuracy.
3Stability of the object's composition
If the sensor system uses its own system clock derived from the natural frequency for frequency determination, then internal consistency is maintained, but the frequency can only be determined indirectly and with limited accuracy
Solution Approach 1:
The patent uses the output data rate, which contains more information than just the basic system clock signal. By analyzing the output data rate that reflects the actual oscillation frequency, the system obtains partial but more accurate frequency information that exceeds the precision of the internal system clock alone.
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 precise compensation of frequency deviations, improving the accuracy of inertial sensor measurements by adapting sensitivity and offset parameters based on the ascertained frequency changes.
Implementation Method 1
the Coriolis forces acting as a result of the external rotation are detected via deflections of the mass running perpendicular to the drive oscillation. The Coriolis force is defined by the speed v of the mass and the external angular rate Ω present: Fcoriolis=−2vΩ
Implementation Method 2
the frequency of the sensor-internal oscillator is ascertained with the aid of the reference clock generator of the evaluation unit. The evaluation unit in this case measures the time rate of the output data received by the sensor on the basis of the time base provided by the reference clock generator
Data Source
AI summary
A system having an inertial sensor and an evaluation unit. The inertial sensor is configured to excite an oscillatory structure of the inertial sensor to execute a drive oscillation, so that an output data rate of the inertial sensor is derived as a function of a frequency of the drive oscillation. The evaluation unit has a reference clock generator and is configured to ascertain the output data rate of the inertial sensor as a function of a reference frequency of the reference clock generator and to determine the frequency and/or frequency change of the drive oscillation as a function of the ascertained output data rate. Alternatively, the inertial sensor is configured to receive a reference clock signal of the reference clock generator from the evaluation unit and to determine the frequency and/or frequency change as a function of the transmitted reference clock signal.