DC Motor Simulation with ARM Based Hardware in the Loop

Recen Inno a ions in Mecha onics (RIiM) Vol. 3. (2016). No. 1-2. DOI: 10.17667/ iim.2016.1-2/15. DC Mo o Simula ion wi h ARM Based Ha dwa e in he Loop Sándo Csikós Uni e si y o Szeged Facul y o Enginee ing TechnicalIns i u e Szeged, Hunga y [email protected] Ádám Bálin Uni e si y o Szeged Facul y o Enginee ing Technical Ins i u e Szeged, Hunga y Abs ac —Ha dwa e in he loop es ing is inc easingly impo an p oduc es ing o cu ing down ime o ma ke . In my p e ious a icle I iden i ied he pa ame e s o a DC mo o con ol sys em using sys em iden i ica ion. An implemen a ion o he esul ing ans e unc ion was de eloped on an ARM based ha dwa e in he loop sys em and has been e i ied agains he o iginal sys em. The esul s show ha he ha dwa e in he loop sys em p oduces esponses wi hin ole ance o he s imulus signals and can be used o es ing o con olsys ems. Keywo ds—Ha dwa e in he loop, LabVIEW, ARM mic ocon olle I. INTRODUCTION Model based design is a me hodology used in designing and es ing con olle so wa e implemen ed in PLCs o mic ocon olle s. The h ee phases ha phases o model based design a e model in he loop (MIL) whe e only he ma hema ical ep esen a ions o he plan and con ol sys em a e used, so wa e in he loop (SIL) whe e a simula ed implemen a ion o he con olle con ols a simula ion o he plan and ha dwa e in he loop (HIL) whe e a eal con olle con ols a eal- ime simula ion o a plan . As he las simula ion s age o p oduc de elopmen ha dwa e in he loop simula ion is used o cu down es ing ime, ensu e he co ec ness o he implemen ed con ol algo i hm and dec ease es ing cos s. As such i is impo an o make he simula ing de ice be as close o he eal sys em as possible. Cu en applica ions use eal- ime ope a ing sys ems o ensu e he high e esh a e needed o such simula ions and a e usually qui e cos ly such as he dSPACE simula o o he Na ional Ins umen s PXI sys ems jus o name a ew. Real- ime compu ing is di ided in o so eal- ime, whe e he use ulness o a esul deg ades a e i s deadline, i m eal- ime whe e in equen deadline misses a e ole a ed and ha d eal- ime whe e missing a deadline is o al sys em ailu e. Missing deadlines deg ades he sys ems quali y he e o e a ha d eal- ime simula ion me hod would gi e us he bes esul s. The e a e nume ous eal- ime simula ions (RTS) cu en ly in li e a u e [1-6], howe e hese sys ems a e so eal- ime. Simila esea ch has been conduc ed by [7] eaching simula ion s ep imes o 250-50 µs wi h a low cos ha dwa e implemen a ion. In his pape expe imen s we e concluded o see i a low cos implemen a ion using an ARM p ocesso could achie e he same esul s o simple sys ems, hus u he lowe ing he es ing cos o es ing, also p o iding an oppo uni y o c ea e a sys em o he a e age use . Such a sys em could also be used in educa ion due o he low p ice and s ong connec ion o he cu en con ol sys ems cou se ma e ial being augh a he Uni e si y o Szeged. The desi ed end esul would be o c ea e a amewo k ha enables ha d eal- ime ha dwa e in he loop es ing o linea ime in a ian MIMO sys ems and sys ems wi h nonlinea cha ac e is ics such as he pneuma ic a i icial muscle (PAM) since he o he main esea ch opic a he Uni e si y o Szeged Facul y o Enginee ing is he high accu acy posi ioning o pneuma ic a i icial muscles o obo ics and ehabili a ion applica ions [8]. II. METHODOLOGY The hypo hesis being es ed was ha a 32bi ARM mic ocon olle could be used o ha d eal- ime ha dwa e in he loop simula ion. The mic ocon olle chosen was he STM32F746ZGT6 on he STM32F746 Nucleo boa d (Fig. 1). Fig. 1. STM32F746 Nucleo boa d The STM32F746ZGT6 ea u es a 216 MHz ARM p ocesso wi h a buil in single p ecision loa ing poin uni enabling ope a ions on numbe s ep esen ed as loa s o be comple ed unde a couple o cycles depending on he ope a ion. A loa ing poin uni is o key impo ance as i will be shown. The p og amming en i onmen used was he Keil MDK wi h he STM32CubeMX o pin se up and ini ializa ion.Measu emen s we e done using LabVIEW, he Recen Inno a ions in Mecha onics (RIiM) Vol. 3. (2016). No. 1-2. DOI: 10.17667/ iim.2016.1-2/15. da a acquisi ion de ice used was a myRIO (Fig. 2) om Na ional Ins umen s. Fig. 2. myRIO om Na ional Ins umen s To es he hypo hesis a physical sys em was cons uc ed consis ing o a small DC mo o wi h a magne moun ed on he o a y sha and an AS5145 absolu e magne ic o a y encode wi h 12 bi s o esolu ion moun ed pe pendicula o he sha (Fig. 3). Fig. 3. Sys em o be simula ed.DC mo o wi h magne and AS5145 magne icencode . The p ocedu e used was he ollowing. Assuming he model o he sys em o be he one shown on Fig. 4 whe e he inpu o he sys em is ol age and he ou pu is he o a ional speed o he sha equa ion (1) and (2) can be de i ed. Fig. 4. Block diag am o mo o whe e:  – ol age di e ence be ween + and - inV  i– cu en lowing h ough he mo o inA  R – esis ance o he mo o inΩ  L – induc ance o he mo o inH  K – cons an o p opo ionali y inV/ ad/s  J – ine ia inkgm2  b – o a ional dampening cons an Nms/ ad  󰇗 – o o speedin ad/s F om he block diag am equa ion (1) and (2) can be de i ed. (1) (2) Knowing equa ion (1) and (2) we can apply he Laplace ans o m o hem. By exp essing he cu en we can subs i u e (1) in (2) and exp ess he ans e unc ion o he mo o (3) whe e he ol age is he inpu and o o speed is he ou pu . ( ) 󰇗 ( ) ( ) ( ( ) ) (3) Knowing he nomina o and denomina o o de s o he ans e unc ion polynomials enables he pa ame ic sys em iden i ica ion o he sys em once a s ep inpu o 1 V has been applied and i s esponse measu ed. Since he o a y encode only gi es ou absolu e posi ion he angula eloci y had o be calcula ed. To calcula e he angula eloci y an FPGA p og am had been w i en ha uns pe iodically e e y 400 µs. The esul s ob ained and he esul o he sys em iden i ica ion can be seen on Fig. 5. Fig. 5. Resul s o measu emen (blue) and sys em iden i ica ion ( ed) The ans e unc ion om sys em iden i ica ion can be seen in equa ion (4) Recen Inno a ions in Mecha onics (RIiM) Vol. 3. (2016). No. 1-2. DOI: 10.17667/ iim.2016.1-2/15. ( ) 󰇗 ( ) ( ) ( ) (4) To implemen he acqui ed ans e unc ion on he mic ocon olle a bilinea ans o ma ion was pe o med wi h he sampling equency o 100kHz o ans o m i om he s plane o he z plane gi ing us equa ion (5) wi h he ollowing coe icien s. ( ) 󰇗 ( ) ( ) ( ) (5) Using an in e se z- ans o m he di e ence equa ion was ob ained om he disc e e ime ans e unc ion. Implemen ing he disc e e ime ans e unc ion is a simple ma e . Since he equa ion only con ains addi ion mul iplica ion and sub ac ion and each o hese ope a ions only equi es 1-3 cycles o he ARMmic ocon olle . III. RESULTS Fig. 6 shows a measu emen o a s ep inpu applied o he implemen ed ha dwa e in he loop sys em in con as wi h a pu e ma hema ical model. Fig. 6. Resul s o s ep inpu applied o ha dwa e in he loop (squa es) and con inuous ime sys em model ( ed) F om he compa ison i is isible ha he wo esponsesa e close o each o he , wi h an a e age absolu e e o o 0.88004 ad/s we concluded ha using an ARMmic ocon olle is iable o ha d eal- ime ha dwa e in heloop simula ion. The STM32F746ZGT6 has a 12 bi analoginpu wi h a maximum sampling equency o 2.4 MHz husplacing he maximum sampling equency o he bilinea ans o ma ion a 2.4 MHz, in iple in e lea e mode hesampling equency can be boos ed o 7.2 MHz, doing so educes he capabili ies o he mic ocon olle o a single inpu sys em. REFERENCES [1] S. Len ijo, A. Mon i, E. San i, C. Welch, and R. Dougal, “A new es ing ool o powe elec onic digi al con ol,” in P oc. IEEE PESC, Jun. 2003, ol. 1, pp. 107–111. [2] V. Dina ahi, R. I a ani, and R. 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