Change search
ReferencesLink to record
Permanent link

Direct link
Design and optimization of a signal converter for incremental encoders: A study about maximizing the boundary limits of quadrature pulse conversion
KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.).
KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.).
2016 (English)Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesisAlternative title
Design och optimering av signalkonverterare for inkrementella encodrar (Swedish)
Abstract [en]

This project was carried out during spring 2016 in collaboration with BOSCH Rexroth, Mellansel, and aimed to investigate the possibility of implementing a converter with the ability to scale incremental pulse resolution and also convert the velocity to a 4-20mA current loop reference. An investigation on how a fault tolerance mechanism could be implemented to increase the dependability of the encoder was done and the out-coming results were implemented. The software and hardware were revised and optimized to facilitate a future encapsulation, and still keep the converter reprogrammable.

A background study was performed during 8 continuous weeks to acquire enough knowledge about possible conversion techniques, to nally derive these down to two for further testing. The nal conversion algorithms were multiplication and extrapolation techniques, which would be utilized to scale the pulse signal. The background study also involved writing ecient c code and a general study about fault tolerance. With the information from the background study, two algorithms were implemented on a specially designed hardware platform. Tests were designed from the requirements given from Bosch and these were performed at a test rig with a magnetic ring encoder connected to dSPACE control desk.

A converter that met the criteria was designed and implemented. The test results showed that the most successful algorithm implemented was the multiplication algorithm, optimized with adaptive resolution, which decreases the input update rate with increasing speed. Although extrapolation caused more noiseand also a static error on the signal, this is the one leaving most room for future optimizations. Dependability means were implemented which stops the converter from outputting erroneous pulses, and also to reboot the software in case of invalid inputs. Whether this made the converter fail-safe or not is dicult to tell since fail-safe is a vague term and applies di erent for each situation. It was concluded that the implemented fault tolerance mechanism worked though. The software and hardware were designed so reprogramming is possible even though the component is casted. This particular function was not tested since the development board did not provide access to the required pins.

Abstract [sv]

Detta projekt genomfordes under varen 2016 i samarbete med Bosch Rexroth i Mellansel. Syftet var att undersoka mojligheten att implementera en konverterare med mojligheten att steglost skala encodersignaler med olika pulstal, samt konvertera detta till en 4-20mA stromsignal. En utredning om hur felsakerheten skulle kunna forbattras pa konverteraren gjordes och resultaten fran undersokningen implementerades. Mjukvaran och hardvaran reviderades och optimerades for hur denna skulle kunna gjutas in for att klara industrins harda inkapslingskrav men samtidigt vara mojlig att programmera om.

En bakgrundsstudie utfordes underatta veckor for att tillgodose tillracklig kunskap om konverteringsalgoritmer for att komma fram till tva stycken for implementation. De slutgiltiga konverteringsalgoritmerna som togs vidare till implementation och testning blev multiplikation och extrapolering av pulstider. Forstudien omfattade aven hur skrivande av e ektiv c kod kan goras da hog hastighet och upplosning kraver mycket berakning av processorn, och en bakgrundsstudie om felsakerhet i elektroniska system. Testfall designades for att testa onskade egenskaper och gransvarden for konverteringarna och dessa utfordes pa en testrig med en magnetencoder uppkopplad mot dSPACE Control Desk.

En konverterare, vilket inte kunde hittas i bakgrundsstudien, designades och implementerades. Testresultaten visade att den mest framgangsrika algoritmen i dessa tester var multiplikationen med en adaptiv upplosning vilken reducerar antalet matpunkter pa insignalen vid hogre hastigheter. Aven om extrapolation i detta fall orsakade bade mer statiskt fel och brus pa signalen sa ar det fortfarande den algoritm dar mest utrymme nns for vidare utveckling och forbattring. Felsakerhetsfunktion implementerades vilket hindrar konverteraren fran att skicka ut ogiltiga pulser vid felaktiga insignaler, och som aven startar om enheten om nagot gatt fel som ett forsok att ratta till detta. Huruvida detta gjorde konverteraren felsaker eller inte ar svart att saga, da termen ar ganska vid och utspelar sig olika fran fall till fall. Slutsatsen ar dock att den implementerade funktionen gjorde konverteraren mer felsaker med sina forvantade funktioner. Mjukvara och hardvara optimerades och designades for att en framtida ingjutning skulle vara mojlig av konverteraren. Denna funktion kunde dock ej testas da utveckligsplattformen ej gav tillgang till de nodvandiga ingagarna pa processorn.

Place, publisher, year, edition, pages
2016. , 93 p.
, MMK 2016:95 MDA 554
National Category
Mechanical Engineering
URN: urn:nbn:se:kth:diva-192301OAI: diva2:967570
External cooperation
Bosch Rexroth
Available from: 2016-09-09 Created: 2016-09-09 Last updated: 2016-09-09Bibliographically approved

Open Access in DiVA

fulltext(1959 kB)8 downloads
File information
File name FULLTEXT01.pdfFile size 1959 kBChecksum SHA-512
Type fulltextMimetype application/pdf

By organisation
Machine Design (Dept.)
Mechanical Engineering

Search outside of DiVA

GoogleGoogle Scholar
Total: 8 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

Total: 36 hits
ReferencesLink to record
Permanent link

Direct link