Author Archives: odtu_ee

PHI or PSI: 2 flavours of error propagation models

In order to be able to write a Kalman filter for your INS, you have to derive a linear error propagation model for your navigation system. In the existing literature, such error propagation models are broadly categorized into 2 groups. … Continue reading

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Comments on “inertial sensor prices”

“vendor-XYZ” has sent me the following comments regarding to the previous blog post. As his comments contain precious information for any INS designer, I am reposting them here with his permission.  “The sensor manufacturers keep everything related with their sensors … Continue reading

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Inertial sensor prices

The sensor manufacturers keep everything related with their sensors as confidential. They are even unwilling to share the per unit price of their sensors. And yet, they seriously expect us to decide on selecting their units without actually knowing any … Continue reading

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On the bias and flicker noise of inertial sensors

What is bias anyway? Commonsense says that it is the sensor output when the input is 0. Therefore, if you align your gyroscope to the East and read 2.5434V at the output, you may think that you can call this … Continue reading

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Zero motion detector for inertial sensors

Zero motion detection for low cost MEMS units is an extremely important topic that has not received enough attention in the navigation community. For most low-cost inertial navigation applications, the only aiding source that can be used to limit the … Continue reading

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On the singularity of the attitude representations

How many times have you read this statement in a paper related with the inertial navigation: “…because of the singularity problem of Euler angles, quaternion representation is used in this study…” It looks quite a legitimate statement, doesn’t it. It … Continue reading

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Sampling Analog Inertial Sensors

In serious navigation projects, analog inertial sensors must be preferred instead of sensors with digital outputs. Some form of analog to digital converter (ADC) is required in order to read the outputs from these analog sensors. Selection of a proper … Continue reading

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Sample STM32F4 Codes to interfere with the Inertial Sensors

(First of all, you can check out the sample codes from here) In my navigation projects, I started to use STM32F4 discovery board as a basic prototyping board. It is STM’s microcontroller evaluation board which costs only 19$. Despite its … Continue reading

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MEMS gyroscopes and their sinusoidal errors.

Almost all low cost MEMS gyroscope outputs are contaminated with additive sinusoidal noises. However, these additive sinusoidals are hindered by the additive white noise (ARW) most of the time. Therefore, these components are usually missed in the inertial sensor models … Continue reading

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In a project that I am somehow involved these days, I needed to select a microcontroller for inertial data logging and processing. It has been a long time since I last programmed a microcontroller. Being somehow away from the hardware, … Continue reading

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