Publicação
Eddy currents based position sensor
| Resumo: | Position sensors are a frequently use in electronic applications. They measure a linear or angular position based on a known arbitrary reference. Specifically, angular position sensors (APS) are widely used in several fields, such as automation, robotic and automotive. Their environment requires for robust and reliable further increasing demand and complexity of sensors. Along the years, magnetic based sensors have been the most resourced angular position sensor over the last few years. Specifically, in the automotive industry, they are used due to their immunity to contaminants, e.g. oil or dirt, robustness towards mechanical shock and their non-contact measurement. But, as electrification of the powertrain and autonomous driving continues, the conventional angular position sensors are becoming inadequate as they are susceptible to external magnetic fields and their raw material (permanent magnets) is becoming scarcer, thus, more expensive. Inductive Position Sensors are a promising alternative technology. These provide a magnet-free and contactless measurement, very low cost, and can be designed to be immune against external magnetic fields. The conversion of the geometrical measurand into electrical quantity is the result of the sum of the excitation coil’s variating magnetic field and the induced magnetic field in the metal target. The University of Minho, in partnership with Bosch, through the Sensible Car project, is developing a inductive APS prototype called Differential Coils. With common automotive electronics and printed coils on a printed circuit board (PCB) and a conductive target, it is possible achieve measurement of angular displacement by exploiting the eddy currents (Foucault). The application to be ran on the MCU, was first simulated, and tested using MATLAB and optimized to be supported on the selected S32k116 MCU. Only after the development of a software stack, the calculation algorithm was then optimized using a fixed-point arithmetic approach, in order to reduce computational strain. The result was a significant decrease to 1/3 in computational effort made on the MCU when comparing a fixed-point arithmetic and floating-point arithmetic. But, consequently, a duplication of the maximum error was made, 0.332 degrees in floating-point arithmetic and 0.699 degrees in fixed-point arithmetic. |
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| Autores principais: | Vale, Luís Manuel Silva Domingues do |
| Assunto: | Eddy currents Fixed-point arithmetic Angular position sensor Correntes eddy Aritmética de ponto fixo Sensor de posicionamento angular Engenharia e Tecnologia::Engenharia Eletrotécnica, Eletrónica e Informática |
| Ano: | 2021 |
| País: | Portugal |
| Tipo de documento: | dissertação de mestrado |
| Tipo de acesso: | acesso aberto |
| Instituição associada: | Universidade do Minho |
| Idioma: | inglês |
| Origem: | RepositóriUM - Universidade do Minho |
| Resumo: | Position sensors are a frequently use in electronic applications. They measure a linear or angular position based on a known arbitrary reference. Specifically, angular position sensors (APS) are widely used in several fields, such as automation, robotic and automotive. Their environment requires for robust and reliable further increasing demand and complexity of sensors. Along the years, magnetic based sensors have been the most resourced angular position sensor over the last few years. Specifically, in the automotive industry, they are used due to their immunity to contaminants, e.g. oil or dirt, robustness towards mechanical shock and their non-contact measurement. But, as electrification of the powertrain and autonomous driving continues, the conventional angular position sensors are becoming inadequate as they are susceptible to external magnetic fields and their raw material (permanent magnets) is becoming scarcer, thus, more expensive. Inductive Position Sensors are a promising alternative technology. These provide a magnet-free and contactless measurement, very low cost, and can be designed to be immune against external magnetic fields. The conversion of the geometrical measurand into electrical quantity is the result of the sum of the excitation coil’s variating magnetic field and the induced magnetic field in the metal target. The University of Minho, in partnership with Bosch, through the Sensible Car project, is developing a inductive APS prototype called Differential Coils. With common automotive electronics and printed coils on a printed circuit board (PCB) and a conductive target, it is possible achieve measurement of angular displacement by exploiting the eddy currents (Foucault). The application to be ran on the MCU, was first simulated, and tested using MATLAB and optimized to be supported on the selected S32k116 MCU. Only after the development of a software stack, the calculation algorithm was then optimized using a fixed-point arithmetic approach, in order to reduce computational strain. The result was a significant decrease to 1/3 in computational effort made on the MCU when comparing a fixed-point arithmetic and floating-point arithmetic. But, consequently, a duplication of the maximum error was made, 0.332 degrees in floating-point arithmetic and 0.699 degrees in fixed-point arithmetic. |
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