Ngā Tikanga Whakahaere PID i roto i te Aunoatanga
I te ao o te aunoatanga ā-umanga, ko te pupuri i tētahi tukanga pumau me te whai kiko te whakaritenga matua. Ahakoa he pupuri i te pāmahana o te oumu ki tētahi uara motuhake, he pupuri i te taumata wai i roto i te tāke, he whakahaere i te tere o te motuka kawe, he whakahaere rānei i te pēhanga i roto i te pūnaha hau—me whai rautaki whakahaere pono katoa. Ko tētahi o ngā tikanga e whakamahia whānuitia ana nā tōna māmā, tōna whai huatanga, me tōna ngāwari ki te whakatinana ko te whakahaere PID (Proportional–Integral–Derivative). Ka matapakihia e tēnei tuhinga ngā ariā taketake o te PID, te mahi a ia wāhanga, tōna tono i roto i te aunoatanga, me ngā mahi whakatikatika mō te mahi tino pai o te pūnaha.
He aha te mana whakahaere PID?
Ko te PID he pūnaha whakahaere urupare e tatau ana i tētahi tohu whakahaere i runga i te rerekētanga i waenga i te uara tohutoro (taurangi tautuhinga) me te uara ine (taurangi tukanga/PV). Ka kiia tēnei rerekētanga ko te hapa. Ko te whāinga o te whakahaere PID ko te whakaiti i te hapa i te wā tere tonu me te kore e meinga te pūnaha kia tino wiriwiri, kia kore rānei e pumau.
I te nuinga o te wā, ka whakaputahia e te kaiwhakahaere he putanga (hei tauira, te whakatuwheratanga o te takirere, te ngaohiko motuka, te huringa mahi PWM rānei) e pā ana ki te tukanga. Ka pānuihia e ngā pūoko te putanga ka whakataurite ki te pūwāhi tautuhinga. Ka haere tonu tēnei huringa i roto i te PLC, DCS, te kaiwhakahaere tāmau rānei.
Te tātai taketake o te āhua tonu o te PID:
u(t) = Kp e(t) + Ki ∫ e(t) dt + Kd · (de(t)/dt)
I roto i ngā pūnaha matihiko (pērā i ngā PLC), ka whakahaerehia ngā tataunga i runga i ngā wā tauira motuhake.
Ngā wāhanga PID: P, I, me D
1) Āhuatanga ōrite (P)
Ka whakaratohia e te wāhanga taurite he urupare e taurite ana ki te rahi o te hapa o nāianei. Mena he nui te hapa, ka nui anō hoki te putanga whakatikatika. Ko te painga he tere me te ngāwari o te urupare.
Heoi, ko te mana whakahaere P-anake ka waiho i te hapa āhua pumau (te hapa e toe ana i muri i te pumau o te pūnaha). Hei tauira, i roto i te mana whakahaere pāmahana, ka noho pea te pāmahana ki raro iho i te pūwāhi tautuhinga nā te mea ka heke te kaha whakatikatika P i te hekenga o te hapa.
Tawhā matua: Kp (whakanuitanga ōwehenga)
– He iti rawa te Kp: he puhoi te urupare, he roa te wā e ngaro ai te hapa.
– He nui rawa a Kp: he mōrearea kei te nui rawa te nekehanga me te wiri.
2) Taupū (I)
Ka tāpirihia e te wāhanga whakauru ngā hapa i roto i te wā. Ko tana mahi he whakakore i ngā hapa āhua pumau, nā te mea ahakoa he iti noa ngā hapa ka haere tonu te akiaki i te putanga kia tata rā anō te hapa ki te kore.
Ko te ngoikoretanga, ka taea e ngā whakaurunga te whakaroa i te urupare, ā, ka puta pea he nui rawa te oscillation, te wiri rānei mēnā he kaha rawa te oscillation. Ko tētahi atu raruraru tawhito ko te integral windup, te wāhi ka "pūpū" rawa ngā whakaurunga ina tae te actuator ki tōna rohe mōrahi/iti (saturation).
Ngā tawhā matua: Ki (te whakanui i te taupū) i ētahi wā ka whakaatuhia ko Ti (te wā taupū)
– He iti rawa te Ki: ka tino pōturi te memeha o te hapa āhua-pūmau.
– He nui rawa te Ki: he nui rawa te tāwhana, he wiriwiri, ā, he ngāwari ki te huripokitia.
3) Whakapūtanga (D)
Ka matapaetia e te wāhanga taupū te ia o te hapa mā te titiro ki tōna tere huringa. Ka taea e te D te āwhina ki te whakaiti i te taikaha me te whakapai ake i te pumau, inā koa i roto i ngā pūnaha e ngāwari ana ki te wiri.
Heoi, he tino tairongo ngā momo pānga ki te haruru o te pūoko. I roto i ngā inenga haruru, ka taea e te D te whakakorikori i te putanga. Nō reira, he maha ngā wā ka haere tahi ngā whakatinanatanga D me te tātari (hei tauira, he tātari pā-iti) ka whakamahia rānei hei momo pānga o te PV (kaua te hapa) hei whakaiti i ngā pānga o ngā huringa ohorere o te tautuhinga.
Ngā tawhā matua: Kd (tāpiritanga hua) Td rānei (tāpiritanga wā)
– He iti rawa te Kd: kāore i te tino kitea te pānga whakaiti.
– He nui rawa te Kd: he tairongo te putanga ki te haruru, ka kore pea te pūnaha e pai, e kore rānei e pumau.
He aha te rongonuitanga o te PID i roto i te aunoatanga?
He maha ngā take whai hua e rongonui ai ngā PID:
1. Ngāwari ki te whakatinana: He poraka mahi PID kei roto i te nuinga o ngā PLC me ngā DCS.
2. Tino ngāwari: Ka taea te whakamahi i roto i ngā tukanga maha (pāmahana, taumata, rere, tere, pēhanga).
3. Kāore e hiahiatia he tauira pāngarau taipitopito: He rerekē ki te mana whakahaere e hangai ana ki te tauira, ka taea te whakarite i te PID mā te whakamahi i tētahi huarahi whakamātautau.
4. Mahi rawaka mō te nuinga o ngā hiahia ahumahi: Mō te nuinga o ngā tukanga, he "pai" te PID i te utu iti.
Heoi, ehara te PID i te otinga mō ngā take katoa—hei tauira, i roto i ngā tukanga tino kore-raina, ngā mea he nui ngā wā mate, ngā tukanga rānei he maha ngā taurangi e taunekeneke kaha ana. I roto i ēnei āhuatanga, he pai ake te whakahaere matatau (hei tauira, MPC) i ētahi wā.
Ngā tauira o ngā tono PID i roto i te ahumahi
1. Whakahaere pāmahana (whakamahana/oumu/pōro)
PV: pāmahana o te thermocouple/RTD
Putanga: te mana whakamahana (SSR/thyristor) te whakatuwheratanga rānei o te takirere mamaoa
Ngā Wero: te ātete wera me te wā mate.
2. Whakahaerehia te taumata o te tāke
PV: taumata wai (whakawhiti ultrasonic/pēhanga)
Putanga: te whakatuwheratanga o te takirere whakauru, te tere papu rānei
Ngā Wero: ngā raruraru mai i te rerenga atu me ngā panonitanga kikī.
3. Whakahaere tere motuka
PV: RPM o te encoder/tachometer
Putanga: tohu ki te puku VFD/servo
Ngā Wero: te whakarerekētanga o ngā kawenga, te waku, me te ngoikore o te miihini.
4. Te whakahaere pēhanga
PV: tuku pēhanga
Putanga: te kaiwhakaoho takirere, te compressor rānei
Ngā Wero: te kaha o te pēhi hau me ngā āhuatanga o te paipa.
Te kaupapa whakahāngai PID (whakahāngai)
Ko te whakahāngai he tukanga e tīpako ana i ngā uara Kp, Ki, me Kd kia tutuki ai i te pūnaha ngā paearu mahi: he tere ki te eke ki te pūwāhi tautuhinga, he iti rawa te taikaha, he pumau, ā, he ātete ki ngā raruraru.
He maha ngā tikanga whakahāngai noa:
1) Whakatakoto ā-ringa (whakamātautau me te hapa)
Ngā huarahi mahi e whakamahia whānuitia ana i te mara:
– Tīmata mai i Ki = 0 me Kd = 0.
– Whakanuia a Kp kia tere rawa te urupare, engari kaua e tino wiri rawa.
– Tāpirihia mārire te Ki hei whakakore i te hapa āhua pumau.
– Tāpirihia te Kd mēnā e tika ana hei whakaiti i te tāwhana me te wiriwiri.
Ko te mea nui ki te whakahāngai ā-ringa ko te mahi i ngā huringa iti, te aroturuki i te urupare takahanga (te huringa o te pūwāhi tautuhinga, te whakararuraru rānei), me te whakarite kia noho haumaru te pūnaha.
2) Ziegler–Nichols (tikanga o te oscillation)
Ko te tikanga matarohia: whakanuia te Kp kia pūmau te wiri o te pūnaha (te pikinga mutunga), tuhia te wā wiri, kātahi ka tatau i ngā tawhā PID mai i tētahi ripanga. He tere tēnei tikanga, engari he maha ngā wā ka puta he nui rawa atu, nō reira kāore i te pai i ngā wā katoa mō ngā tukanga tairongo.
3) Te whakahāngai aunoa i ngā pūmana hou
He maha ngā PLC/pūmana pāmahana e tuku ana i ngā āhuatanga whakahāngai aunoa. I te nuinga o te wā, ka tukuna e te taputapu he tohu whakamātautau, ka tautuhi i te urupare tukanga, kātahi ka tatau i ngā tawhā PID tuatahi. He pai ngā hua hei tīmatanga, engari me whakarerekē pea i runga i ngā whakaritenga tukanga.
Ngā mea nui i roto i te whakatinanatanga o te PID mamati
1. Te wā tauira (Ts)
Mā te puhoi rawa o te tauira ka puhoi te tauhohe a te mana whakahaere. Mā te tere rawa o te tauira ka nui ake te haruru me te taumaha rawa i te CPU. Kōwhiria ngā T kia rite ki ngā nekehanga tukanga: he iti ngā T e hiahiatia ana e ngā tukanga tere, engari ka taea e ngā tukanga puhoi te whakamahi i ngā T nui ake.
2. Te whakakī putanga me te ārai-whakamuri
Ina tae te putanga ki tētahi rohe (hei tauira, 0–100%), ka taea tonu e te taupū te tipu me te whakaputa i te nui rawa atu ina hoki te pūnaha ki te āhua noa. Ka ārai te ārai-whakaeke i te kohikohinga koretake o ngā taupū.
3. Te tātari i ngā pānga me ngā PV
He haruru te nuinga o ngā pūoko. He āwhina te tātari pā-iti, inā koa ka whakamahia ngā wāhanga D.
4. Te pikinga/te tīmatanga ngāwari
Ka taea e ngā huringa ohorere o te ine te whakanui ake i te tere. Mā te whakanui ake i te ine ka māmā ake te whakawhiti.
Ngā paearu mahi noa i aromatawaitia
I roto i te aunoatanga, ko te whakatikatika PID te tikanga e whai ana i te huinga o:
– Te tere o te pikinga (te wā pikinga ki te pūwāhi taunga).
– He iti noa te taikaha (kāore e neke rawa ki tua atu i te pūwāhi i whakaritea).
– He poto te wā taunga (ka tere te whakaū).
– He iti rawa te hapa pumau.
– He pakari pai (ka noho pumau ahakoa ngā huringa o te kawenga/ngā raruraru).
Kāore e taea te whakapai ake i ngā mea katoa i te wā kotahi. Hei tauira, ko te whai kia tere rawa te pikinga ka nui ake te kaha. Nō reira, ko te whakatikatika e whakawhirinaki ana ki ngā kaupapa matua o te tukanga: te haumaru, te kounga o te hua, te whai hua o te pūngao, te whakamarie whakahaere rānei.
Te Katinga
Ko ngā tikanga whakahaere PID te poutokomanawa o te maha o ngā pūnaha aunoa nā te mea ka taea e rātou te whakahaere pai i ngā tukanga me te whakatinanatanga ngāwari noa iho. Mā te mārama ki ngā mahi a ngā wāhanga P, I, me D, me te whakamahi i ngā mahi whakatikatika me te whakatinanatanga pai—pēnei i te ārai-whakaoho, te tātari, me te wā tauira—ka taea e te PID te whakarato i te mahi pumau, te aro, me te ātete ki te hapa i roto i te whānuitanga o ngā tono ahumahi. Ahakoa te wātea mai o ngā tikanga whakahaere hou matatau ake, ko te PID tonu te whiringa pai mō te maha o ngā tukanga nā te mea he pai te taurite o te mahi, te māmā, me te utu.
Ki te hiahia koe, ka taea e au te whakarerekē i tēnei tuhinga ki tētahi horopaki motuhake (hei tauira, te PID i runga i te Siemens/Omron PLC, te whakahaere pāmahana me ngā SSR, he tauira rānei o ngā tataunga whakahāngai mō te pūnaha taumata motuka/tāke).
