Inertial Sensor Data Readout Frequency Ratio Determination
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Solution Overview
Problem
Inertial sensors operating in slave mode face challenges in accurately reading data at read-out times due to frequency mismatches between read-in and read-out frequencies, leading to incomplete representation of movement data and beat effects, as existing solutions require knowledge of the read-out frequency which is often not available.
Innovation Solution
A method involving a low-pass filter to determine the ratio between read-in and read-out frequencies, allowing inertial sensors to extrapolate data and adjust it to reflect the actual movement, even when the read-out frequency is unknown, by counting data path cycles and using this ratio to generate output data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If data is read at a read-out frequency that is not synchronized with the read-in frequency, then the sensor can operate in slave mode with external frequency control, but the read data does not accurately represent the actual movement and beat effects occur
Solution Approach 1:
The patent applies preliminary action by determining the ratio N between read-in and read-out frequencies in advance, before generating the output data. This ratio is used to calculate the correct number of data path cycles to accumulate, ensuring that the integration period exactly matches the query cycle even when operating in slave mode with unsynchronized frequencies.
Solution Approach 2:
The patent implements dynamics by making the accumulation period adaptive rather than fixed. The system dynamically adjusts the number of data path cycles to accumulate based on the determined ratio N, allowing the sensor to accurately represent movement data across varying read-out frequencies without requiring synchronization.
2Measurement precision
If the read-out frequency is exactly synchronized with the read-in frequency, then the read data accurately represents the movement, but the sensor cannot operate in slave mode with external frequency specification
Solution Approach 1:
The patent determines the frequency ratio N in advance, before data accumulation begins. This preliminary determination allows the system to pre-calculate the exact accumulation period needed, enabling accurate movement representation without requiring the read-out frequency to be synchronized with or known to the sensor.
Solution Approach 2:
The patent introduces the ratio N as an intermediary parameter that bridges the gap between read-in and read-out frequencies. This intermediate value allows the system to translate between the two frequency domains, enabling slave mode operation while maintaining measurement accuracy without direct frequency synchronization.
3Ease of operation
If an integer number of data path cycles is used for accumulation, then the data reading is simple, but the accumulation period does not exactly match the query cycle leading to incomplete movement representation
Solution Approach 1:
The patent changes the parameter of accumulation period from a fixed integer number of data path cycles to a dynamically calculated value based on the ratio N. This parameter change allows the accumulation period to exactly match the query cycle, ensuring complete movement representation while maintaining simple data reading operations.
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
This method ensures that the data read at read-out times accurately represents the movement, meeting both integral and differential error criteria, thereby improving the accuracy of inertial navigation systems without requiring knowledge of the read-out frequency.
Implementation Method 1
determining, by means of a low-pass filter of the sensor, the ratio N between the read-in frequency fa and the read-out frequency fs from the time sequence of the numbers of the read-in times lying between two adjacent read-out times
Data Source
AI summary
A method for reading data from sensors is disclosed comprising: determining a sequence of measured data over time by means of a sensor, wherein the sequence of measured data over time is generated by step-by-step changes in the measured data at input times, which are determined by an input frequency fa and have a time interval of a period 1/fa of the input frequency; reading output data from the sensor at read times, which are determined by a read frequency fs and have a time interval of a period 1/fs of the read frequency, where the read frequency fs is smaller than the input frequency fa; determining, by means of a low-pass filter of the sensor, the ratio N between the input frequency fa and the read frequency fs from the sequence over time of the numbers of input times lying between two adjacent read times.