応用分野9: アプライアンス設計

機械式加速度計を使用して、ロケットの試験スレッドの加速度を測定します。この測定では、線形のスプリングダンパシステムを扱います。以下に図を示します。剛性と減衰を調整することで、感知された加速度が許容時間内で推定されるように加速度計を設計できます。



図 1.
目的
ターゲット値 x * MathType@MTEF@5@5@+= feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaebbnrfifHhDYfgasaacH8srps0l bbf9q8WrFfeuY=Hhbbf9v8qiqrFr0xc9pk0xbba9q8WqFfea0=yr0R Yxir=Jbba9q8aq0=yq=He9q8qqQ8frFve9Fve9Ff0dmeGabeqadiWa ceGabeqabeqadeqadmaakeaaieGaqaaaaaaaaaWdbiaa=HhapaWaaW baaSqabeaapeGaa8Nkaaaaaaa@3415@ からのシステム応答 x MathType@MTEF@5@5@+= feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaebbnrfifHhDYfgasaacH8srps0l bbf9q8WrFfeuY=Hhbbf9v8qiqrFr0xc9pk0xbba9q8WqFfea0=yr0R Yxir=Jbba9q8aq0=yq=He9q8qqQ8frFve9Fve9Ff0dmeGabeqadiWa ceGabeqabeqadeqadmaakeaaieGaqaaaaaaaaaWdbiaa=Hhaaaa@331E@ の偏差を次のように計算できます:
(1)
S T E P ( t t a r g e t ) = { 0   i f   t t t a r g e t 1   i f   t > t t a r g e t MathType@MTEF@5@5@+= feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaebbnrfifHhDYfgasaacH8srps0l bbf9q8WrFfeuY=Hhbbf9v8qiqrFr0xc9pk0xbba9q8WqFfea0=yr0R Yxir=Jbba9q8aq0=yq=He9q8qqQ8frFve9Fve9Ff0dmeGabeqadiWa ceGabeqabeqadeqadmaakeaaieGaqaaaaaaaaaWdbiaa=nfacaWFub Gaa8xraiaa=bfadaqadaWdaeaapeGaa8hDa8aadaWgaaWcbaWdbiaa =rhacaWFHbGaa8NCaiaa=DgacaWFLbGaa8hDaaWdaeqaaaGcpeGaay jkaiaawMcaaiabg2da9iaa=bkadaGabaWdaeaafaqabeGabaaabaWd biaaicdacaWFGcGaa8xAaiaa=zgacaWFGcGaa8hDaiaa=bkacqGHKj YOcaWFGcGaa8hDa8aadaWgaaWcbaWdbiaa=rhacaWFHbGaa8NCaiaa =DgacaWFLbGaa8hDaaWdaeqaaaGcbaWdbiaaigdacaWFGcGaa8xAai aa=zgacaWFGcGaa8hDaiabg6da+iaa=bkacaWF0bWdamaaBaaaleaa peGaa8hDaiaa=fgacaWFYbGaa83zaiaa=vgacaWF0baapaqabaaaaa GcpeGaay5Eaaaaaa@6101@
(2)
f ( x ) = t s t a r t t e n d S T E P ( t t a r g e t ) *   | x x * | d t MathType@MTEF@5@5@+= feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaebbnrfifHhDYfgasaacH8srps0l bbf9q8WrFfeuY=Hhbbf9v8qiqrFr0xc9pk0xbba9q8WqFfea0=yr0R Yxir=Jbba9q8aq0=yq=He9q8qqQ8frFve9Fve9Ff0dmeGabeqadiWa ceGabeqabeqadeqadmaakeaaieGaqaaaaaaaaaWdbiaa=zgadaqada WdaeaapeGaa8hEaaGaayjkaiaawMcaaiabg2da9maawahabeWcpaqa aaqaaaqdbaWdbiabgUIiYpaaDaaaoeaacaWF0bWdamaaBaaabaWdbi aa=nhacaWF0bGaa8xyaiaa=jhacaWF0baapaqabaaapeqaaiaa=rha paWaaSbaaeaapeGaa8xzaiaa=5gacaWFKbaapaqabaaaaaaak8qaca WFtbGaa8hvaiaa=veacaWFqbWaaeWaa8aabaWdbiaa=rhapaWaaSba aSqaa8qacaWF0bGaa8xyaiaa=jhacaWFNbGaa8xzaiaa=rhaa8aabe aaaOWdbiaawIcacaGLPaaacaWFQaGaa8hOamaaemaapaqaa8qacaWF 4bGaeyOeI0Iaa8hEa8aadaahaaWcbeqaa8qacaWFQaaaaaGccaGLhW UaayjcSdGaa8hzaiaa=rhaaaa@5A37@
この問題は次のように定式化できます:
min    ( x x * ) 2 | steady state MathType@MTEF@5@5@+= feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaebbnrfifHhDYfgasaacH8srps0l bbf9q8WrFfeuY=Hhbbf9v8qiqrFr0xc9pk0xbba9q8WqFfea0=yr0R Yxir=Jbba9q8aq0=yq=He9q8qqQ8frFve9Fve9Ff0dmeGabeqadiWa ceGabeqabeqadeqadmaakeaaqaaaaaaaaaWdbiaah2gacaWHPbGaaC OBaiaacckacaGGGcGaaiiOaiaacckacaGGOaWaaqGaa8aabaacbiWd biaa=HhacqGHsislcaWF4bWdamaaCaaaleqabaacbaWdbiaa+Pcaaa GccaGGPaWdamaaCaaaleqabaWdbiaaikdaaaaakiaawIa7a8aadaWg aaWcbaWdbiaa=nhacaWF0bGaa8xzaiaa=fgacaWFKbGaa8xEaiaa+b kacaWFZbGaa8hDaiaa=fgacaWF0bGaa8xzaaWdaeqaaaaa@4D4C@
such that    f( x )<1e3 MathType@MTEF@5@5@+= feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaebbnrfifHhDYfgasaacH8srps0l bbf9q8WrFfeuY=Hhbbf9v8qiqrFr0xc9pk0xbba9q8WqFfea0=yr0R Yxir=Jbba9q8aq0=yq=He9q8qqQ8frFve9Fve9Ff0dmeGabeqadiWa ceGabeqabeqadeqadmaakeaaqaaaaaaaaaWdbiaadohacaWG1bGaam 4yaiaadIgacaGGGcGaamiDaiaadIgacaWGHbGaamiDaGqaaiaa=bka caWFGcGaa8hOaiaa=bkaieGacaGFMbWaaeWaa8aabaWdbiaa+Hhaai aawIcacaGLPaaacqGH8aapcaaIXaGaa4xzaiabgkHiTiaaiodaaaa@4736@
設計変数
スプリングの剛性 k MathType@MTEF@5@5@+= feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaebbnrfifHhDYfgasaacH8srps0l bbf9q8WrFfeuY=Hhbbf9v8qiqrFr0xc9pk0xbba9q8WqFfea0=yr0R Yxir=Jbba9q8aq0=yq=He9q8qqQ8frFve9Fve9Ff0dmeGabeqadiWa ceGabeqabeqadeqadmaakeaaieGaqaaaaaaaaaWdbiaa=Tgaaaa@3311@ と、その減衰 c MathType@MTEF@5@5@+= feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaebbnrfifHhDYfgasaacH8srps0l bbf9q8WrFfeuY=Hhbbf9v8qiqrFr0xc9pk0xbba9q8WqFfea0=yr0R Yxir=Jbba9q8aq0=yq=He9q8qqQ8frFve9Fve9Ff0dmeGabeqadiWa ceGabeqabeqadeqadmaakeaaieGaqaaaaaaaaaWdbiaa=ngaaaa@3309@ が設計変数です。
結果
スプリングの剛性と減衰を適切に選択することで、目的の時間フレーム内で応答するように加速度計を設計できます。


図 2.