Izboljšanje ločljivosti magnetnega senzorja zasuka z vezjem FPGA

RECELJ, NEJC (author), Žemva, Andrej (mentor)

Cilj magistrske naloge je bil doseči višjo ločljivost za 12-bitni magnetni senzor zasuka AM4096, ki bere položaj magneta in sporoča njegovo pozicijo v različnih izhodnih oblikah. Senzor ima prisoten šum na inkrementalnem izhodu in se pojavlja ob prehodu iz ene pozicije na drugo ter je v trenutni izvedbi enkoderja odpravljen s histerezo. V moji nalogi sem šum na inkrementalnem izhodu filtriral s filtrom tekočega povprečja. Zaradi potrebe po hitrih odzivih sem filtriranje implementiral na vezju FPGA, ki je hitrejši od mikroprocesorjev in lahko več operacij izvaja hkrati. To je bil tudi razlog, da sem uporabil najenostavnejši FIR filter, ker je za implementacijo na FPGA najlažji. Na začetku sem podal teoretično rešitev, ki je potrdila, da filtriranje lahko poveča ločljivost senzorja. V drugem delu je opisana implementirana rešitev in delovanje filtra v realnih razmerah ter prikaz rezultatov filtriranega inkrementalnega signala. S filtriranjem je bilo dosežena 14-bitna ločljivost in odpravljen šum. Dodana sta 2 nova bita, kar omogoča, da senzor loči 16384 pozicij namesto prejšnjih 4096. Na filtriranem izhodnem signalu je negativen efekt to, da je prisoten zamik za velikost filtra, kar pa je bilo predvideno že na začetku.

• Language: Slovenian
• Keywords: magnetni senzor zasuka, filtriranje, FIR, tekoče povprečje
• Work type: Master's thesis/paper
• Organization: FE - Faculty of Electrical Engineering
• Year: 2017
• PID: 20.500.12556/RUL-97592
• Publication date in RUL: 27.10.2017

Secondary language

• Language: English
• Title: Improving resolution of magnetic rotational sensor with FPGA device

Abstract

The of objective in this master thesis was to a achieve higher resolution for 12 bits magnetic rotational sensor AM4096, which gives positional information of the magnet, with different output formats. Sensor makes noise at every time it changes position, which is in the current encoder eliminated with hysteresis. In my work I filtered the present noise with the moving average filter. Since fast responses are required, I used FPGA instead of a microprocessor because all processes thus run faster and in parallel. That was also the main reason why I used the simplest FIR filter, the easiest to implement on the moving average filter. At the beginning of my work I presented a theoretical solution which proved that with filtering, higher resolution can be achieved. In the second part I described the implemented solution and presented the results of the filtered incremental signal. With filtering, 14 bits resolution and reduced noise were achieved. With 2 added bits the encoder can separate 16384 positions of the magnet instead of the previous 4096. Negative effect of the filtering, a delay, was predicted in advance and taken in consideration. Filtering, with all its positive and negative effects, gave positive results and is therefore termed as successful.

• Keywords: rotational magnetic sensor, filtering, FIR, moving average