Estimating three-dimensional motion using IMU sensors
Kivikangas, Marko (2022)
Kivikangas, Marko
2022
Tieto- ja sähkötekniikan kandidaattiohjelma - Bachelor's Programme in Computing and Electrical Engineering
Informaatioteknologian ja viestinnän tiedekunta - Faculty of Information Technology and Communication Sciences
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Hyväksymispäivämäärä
2022-02-28
Julkaisun pysyvä osoite on
https://urn.fi/URN:NBN:fi:tuni-202205104686
https://urn.fi/URN:NBN:fi:tuni-202205104686
Tiivistelmä
Inertial measurement units (IMUs) are sensors that are used to calculate device's state of motion and attitude. The sensors usually consist of accelerometers, gyroscopes and magnetometers. They measure acceleration, angular velocity and the strength of Earth's magnetic field, respectively. At least accelerometers and gyroscopes are needed in a working IMU.
Traditional IMUs have been meachanical and have used large spring-mass systems and rotating discs to acquire the desired data. However, modern sensors rely heavily on microelectromechanical systems (MEMS) that measure changing capacitance. This makes it possible to produce small and low-cost products to consumer markets. Data accuracy is also a key factor in high-grade IMUs such as in aviation and marine applications.
The purpose of this bachelor's thesis is to present the mathematical models of IMUs and what kind of physics are utilized in them. The thesis starts from basic mechanical models but the emphasis moves to MEMS IMUs. Some of the main error sources are also discussed and the ways to minimize them.
The acquired models are tested with real-life data collected with MATLAB Mobile phone application. The test is conducted by moving phone in a circular path starting and ending at the same location. The data is converted to trajectory and accuracy is evaluated by measuring how far the trajectory ends up from the starting position.
The results show that without proper filtering and error minimizing the trajectories are very rough and phone's random movement causes a drastic drift away from trajectory. The results leave room for further experiments done with higher-grade IMU devices. The attitude measurements are left out of the examining but they could be done with the acquired data.
Traditional IMUs have been meachanical and have used large spring-mass systems and rotating discs to acquire the desired data. However, modern sensors rely heavily on microelectromechanical systems (MEMS) that measure changing capacitance. This makes it possible to produce small and low-cost products to consumer markets. Data accuracy is also a key factor in high-grade IMUs such as in aviation and marine applications.
The purpose of this bachelor's thesis is to present the mathematical models of IMUs and what kind of physics are utilized in them. The thesis starts from basic mechanical models but the emphasis moves to MEMS IMUs. Some of the main error sources are also discussed and the ways to minimize them.
The acquired models are tested with real-life data collected with MATLAB Mobile phone application. The test is conducted by moving phone in a circular path starting and ending at the same location. The data is converted to trajectory and accuracy is evaluated by measuring how far the trajectory ends up from the starting position.
The results show that without proper filtering and error minimizing the trajectories are very rough and phone's random movement causes a drastic drift away from trajectory. The results leave room for further experiments done with higher-grade IMU devices. The attitude measurements are left out of the examining but they could be done with the acquired data.
Kokoelmat
- Kandidaatintutkielmat [8354]