Micromechanical Yaw Rate Sensor Digital Feedback Control
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Solution Overview
Problem
Micromechanical yaw rate sensors face challenges in implementing negative force feedback due to phase rotation issues at resonant frequencies, requiring complex bandpass filters that need individual adjustment for each sensor batch, making the process time-consuming and costly.
Innovation Solution
A method involving digital signal processing to generate a digital drive signal at the resonant frequency, in-phase multiplication of Coriolis and drive signals, and low-pass filtering to produce a compensation signal with zero phase shift, allowing for linear negative force feedback without adjustments, using digital circuit technology.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a second-order or higher-order bandpass filter is used to suppress interference above and below the resonance frequency, then the evaluation bandwidth can be controlled and non-linearities reduced, but the filter must have its center frequency exactly at the resonance frequency which requires individual adjustment for each sensor batch, making the process time-consuming and costly
Solution Approach 1:
The patent replaces the mechanical/analog bandpass filter system with a digital signal processing system. The digital filter is implemented through software algorithms that process signals from the oscillating mass, eliminating the need for physical filter components that require manual frequency adjustment. This digital approach allows the filter characteristics to be programmed rather than physically tuned for each sensor.
Solution Approach 2:
The patent changes the parameter of filter implementation from analog/physical to digital/software-based. By using digital signal processing, the filter characteristics can be modified through parameter changes in the software rather than physical adjustments to the filter circuit. This enables universal application across sensor batches without individual adjustment.
2Measurement precision
If a bandpass filter with center frequency exactly at the resonance frequency is used, then interference above and below resonance can be suppressed, but the filter requires individual adjustment for each sensor batch due to variations in oscillator resonance frequencies
Solution Approach 1:
The patent replaces the physical bandpass filter with a digital signal processing system that performs frequency-selective filtering through software. This digital implementation automatically adapts to the actual resonance frequency of each sensor through signal analysis, eliminating the need for manual frequency adjustment of physical filter components during manufacturing.
Solution Approach 2:
The digital signal processing system automatically identifies and adapts to the resonance frequency characteristics of each sensor through self-testing and automatic parameter adjustment. The system performs self-service by analyzing the sensor's actual response and configuring the digital filter accordingly, eliminating the need for external manual adjustment during manufacturing.
3Manufacturing precision
If individual adjustment of bandpass filters is performed for each sensor batch, then the resonance frequency can be precisely matched, but the manufacturing process becomes time-consuming and costly
Solution Approach 1:
The patent replaces the manual adjustment process with automated digital signal processing. The digital filter system automatically analyzes each sensor's resonance characteristics and configures itself without human intervention, enabling high-speed production while maintaining precision. This automation eliminates the time-consuming manual tuning process while preserving frequency matching accuracy.
Solution Approach 2:
The patent performs preliminary characterization of the sensor's resonance frequency during the manufacturing process, and the digital filter is pre-configured based on this analysis. This preliminary action allows the system to be ready for immediate use without requiring additional adjustment time, thereby increasing productivity while maintaining manufacturing precision.
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 and cost-effective realization of linear negative force feedback in micromechanical yaw rate sensors, providing a measured variable proportional to external rotation rates without the need for individual filter adjustments, ensuring the compensation signal is always in phase with the drive signal.
Implementation Method 1
Such sensors are operated at the mechanical resonance frequency both for the oscillator element comprising the mass m and for the Coriolis element comprising the Coriolis mass mC.
Implementation Method 2
the oscillatory elements are to be regarded as elastically suspended masses m... the excitation frequency of the drive force F(t)
Implementation Method 3
If the mass m oscillating in the x-direction is rotated at a rate of rotation Ω about the z-axis running normal to the x-y plane... the mass m experiences an additional periodic acceleration in the γ-direction, which is proportional to the rotation rate Ω. This acceleration is known as the Coriolis acceleration.
Implementation Method 4
a controller ensures that the Coriolis mass mc does not oscillate in the direction of the y-axis and remains at rest in this direction, by means of an additional electrostatic compensation force Fc(t) applied to the Coriolis mass mc
Data Source
Figure 1~2
AI summary
A method for operation of and simultaneous analysis of a rate-of-turn sensor, comprising an oscillator element and a Coriolis element arranged on the oscillation element is disclosed, comprising the following method steps: generation of a digital operating signal with an excitation frequency corresponding to the resonant frequency of the oscillator element, digital to analogue conversion of the digital operating signal and operation of the oscillator element with the analogue operating signal, recording a Coriolis speed of the Coriolis element occurring about a normal to both oscillation axes due to the rotation of the rate-of-turn sensor with generation of an analogue Coriolis signal proportional to the Coriolis speed, analogue-to-digital conversion of the analogue Coriolis signal, phase-sensitive multiplication of the digital Coriolis signal with the digital operating signal to form an intermediate signal, generation of a control signal proportional to the rate of turn of the rate-of-turn sensor from the intermediate signal, multiplication of the control signal with the digital operating signal to give a digital compensation signal in phase with the digital operating signal, digital-to-analogue conversion of the digital compensation signal to give an analogue compensation signal in phase with the analogue operating signal and subjecting the Coriolis element to the analogue compensation signal and output of the control signal.