Ad-hoc Rescheduling and Innovative Business Models for Shock- Robust Production Systems

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1 Avalable onlne a Proceda CIRP 7 (2013 ) Fory Sxh CIRP Conference on Manufacurng Sysems 2013 Ad-hoc Reschedulng and Innovave Busness Models for Shock- Robus Producon Sysems Gsela Lanza a, Ncole Srcker a,*, Seven Peers a a wbk-insue of Producon Scence, Karlsruhe Insue of Technology (KIT), Kasersr. 12, Karlsruhe, Germany. * Correspondng auhor. Tel.: Fax: E-mal address: ncole.srcker@k.edu. Absrac Reconfgurably, flexbly, ransformably and agly become key enablers of success. Ths leads o new busness models and he necessy of new conceps for producon plannng along he whole value chan. Adequae mehods have o negrae he possbles of a mgraon of he nework and he changeably of each sngle plan. Moreover hese approaches should be able o cope wh uncerany and reduce he complexy for he decson-makers o a mnmum. Consequenly, hs paper focuses on wo major aspecs: ad-hoc reschedulng of reconfgurable plans as well as new nnovave busness models beween equpmen or componen suppler and OEM. Cyber-physcal sysems wll enable new decenralzed and auonomously workng producon equpmen and n dong so, reduce complexy and boos up he speed of possble reacons o marke shocks. Componen supplers wll enrch her porfolo by new bundlng approaches ncludng warranes o her producs n erms of rsk prevenon (e.g. warranes for needed me o reac o marke changes or bolenecks) The Auhors. Publshed by by Elsever Elsever B.V. B.V. Selecon and/or peer-revew peer-revew under under responsbly responsbly of Professor Professor Pedro Flpe Pedro do Flpe Carmo do Cunha Carmo Cunha Keywords: Inellgen; adapve and e-manufacurng; busness models 1. Inroducon and curren challenges The las decade showed how, complexy and dynamcs domnae he economes around he world. The naural and nuclear dsaser n Japan showed n very dramac ways how fragle our supply chans can be. Susanable moves n economc crss and fas reacons o changed marke or legal condons become of crucal mporance for all companes as hey all are par of a global chan. Moreover, cusomers expec a hgh degree of ndvdualy and shor delvery mes. Consequenly, reconfgurably, flexbly, ransformably and agly become key enablers of success. Ths leads o new busness models and he necessy of new conceps for producon plannng along he whole value chan. These mehods have o negrae he possbles of a mgraon of he nework and he changeably of each sngle plan. Moreover hese approaches should be able o cope wh uncerany and reduce he complexy for he decson-makers o a mnmum. These curren challenges have o be addressed on very dfferen levels reachng from he global nework level on he one hand o he producon sysems level on he oher hand. Ths paper presens correspondng approaches and s srucured as follows. In chaper 2 a bref overvew of sae of he ar approaches concernng hese opcs are gven. Chaper 3 nroduces Enablers for reachng he named goals. Chaper 4 s focusng on he reacons of nernal shocks on a plan level, whle chaper 5 expands hese consderaons o a global nework level. Chaper 6 closes wh he summary. 2. Sae of he Ar Ths chaper gves an overvew of approaches facng he curren challenges of reconfgurably, flexbly, ransformably and agly whn a complex producng envronmen on he levels of producon neworks and producon sysems. On he nework and supply chan level dfferen approaches can be found. Fleschmann e al [1], Sephan e al [2] and Leung e al [3] focused on capacy plannng of producon neworks on a sraegc level The Auhors. Publshed by Elsever B.V. Selecon and peer-revew under responsbly of Professor Pedro Flpe do Carmo Cunha do: /j.procr

2 122 Gsela Lanza e al. / Proceda CIRP 7 ( 2013 ) Lanza and Peers deal wh capacy plannng for hghly volale horzons for nsance caused by economc crss [4] and negraed possbles of supply chan adapaons. Robus supply chans ha are able o adap o a hghly volale envronmen conss of robus plans whch n urn nclude robus producon sysems. However, shockrobus plans do no only conss of changeable producon sysems whch have been and are sll exensvely suded. Besdes he ably of adapng o exernal changes lke economc crses, global dsasers or changes n local markes, hey also have o be robus concernng nernal shocks. An nernal shock can for example be gven by a sudden machne breakdown. A shock-robus plan has o be able o adap o hs new suaon whn a mnmum of me n order o ensure producon. In hs conex he sgnfcance of reschedulng becomes obvous. In hs feld of research several approaches exs. Gulherme e al [5] descrbe a framework o classfy exsng reschedulng approaches. In he followng hs framework s used o survey exsng approaches. The framework dfferenaes beween reschedulng envronmens, reschedulng sraeges and reschedulng mehods. The erm Reschedulng envronmen denfes he se of jobs and refers o her dynamc naure. Mos approaches consder sac jobs, n whch a fne se of jobs exss (e.g. Gulherme e al [6]). Snce dynamc reschedulng envronmens are he ones mos relevan o manufacurng sysems, he dynamc envronmen nowadays s ncreasngly aken no accoun, as he random job arrval n Gao e al [7]. Thus reschedulng leraure consders dfferen manufacurng ypes lke cyclc producon, flow shops or job shops when focusng on dynamc envronmens. Flow shops are e.g. consdered by Gao e al [7] or Tan e al [8] whereas Dong e al [9] and Hao e al [10] presen algorhms solvng reschedulng problems n job shops. Gulherme e al descrbe wo reschedulng sraeges for conrollng producon n a dynamc envronmen. They propose dynamc sraeges and predcve-reacve sraeges. The laer are he ones mos commonly used n pracce and accordng o Ayug e al [11] also he ones mos suded n leraure. Predcve-reacve sraeges frs generae a producon schedule and hen updae he schedule accordng o dfferen reschedulng polces. Ths reschedulng polces can be eher perodc, even-drven [6, 9] or hybrd [10, 12]. Perodc polces reschedule perodcally a a fxed me, whereas even-drven reschedulng s only akng place, when specfc condons hold. Hybrd polces reschedule a producon schedule a a fxed me perodcally bu also reschedule whenever random dsrupons occur. Reschedulng mehods are eher focusng on schedule generaon or schedule repar. Gulherme e al subdvde schedule repar no rgh-shf reschedulng, paral reschedulng and complee reschedulng. The former smply pospones all remanng operaons. Rgh-shf reschedulng s very easy o mplemen and e.g. observed by [13] who propose rgh-shf reschedulng wh respec o effcency and sably. Paral Reschedulng, also known as Affeced Operaons Reschedulng (AOR) [9], only reschedules operaons affeced by he dsrupon. Accordng o Gulherme e al [5] mos of he approaches consder affeced operaons only. Wang e al [14] consder machne breakdown a a permuaon flow shop. As a soluon mehod a paral reschedulng procedure for he permuaon flow-shop schedulng problem s developed. Dong e al [9] exend he ypcal AOR by proposng heursc reschedulng procedures consderng ardness of jobs n a job shop as her man objecves bu also oher performance measures lke effcency and sably. Complee regeneraon mehods reschedule he enre remanng operaons, also he ones no affeced by he dsrupon. Anoher approach focusng on he area of sably, more precse he opc of reducng he nerference wh producng anomaly by shorenng he searchng space s gven by [15]. Whn he approach of Tan e al [8] he reschedulng mehods of machne-learnng and daamnng echnques generang a knowledge-based decson makng sysem are addressed. Oher approaches lke Gao e al [7] use genec algorhms as a soluon mehod. Gao e al propose a 3-sage reschedulng based on he rollng wndow reschedulng sraegy consderng he mnmum compleon me, mnmum cos, maxmum ulzaon rae, and mnmum devaon degree as objecves. The number of approaches consderng sably and robusness of reschedulng soluons by usng dfferen reschedulng mehods s rsng. Mos approaches however do no consder he ncrease n cos when reschedulng a producon schedule. Moreover accordng o Ayug e al [11] he connecon beween reschedulng leraure and leraure on srucural conrol of auomaed manufacurng sysems s also mssng. Many approaches are only focusng on a sngle producon sysem nsead of a whole producon nework. Bu n fac los of producon anomales are no only caused by machne breakdowns, bu also by mssng componens and oher dsurbances caused by problems n he nework. On he oher hand he nework defnes he crcaly of a break-down as s he nework sufferng under he consequences. So seekng he goal of ncreasng reconfgurably, flexbly, ransformably and agly he whole producon nework ncludng all s producon sysems has o be consdered.

3 Gsela Lanza e al. / Proceda CIRP 7 ( 2013 ) Enabler 3.1. Cyber Physcal Sysems Cyber Physcal Sysems (CPS) are he nex generaon of embedded sysems and can be seen as par of Inerne of Thngs approaches whch are currenly on he run o become an enablng echnology n ndusry [16]. Neworked cyber physcal sysems negrae he soco-echnologcal sysem envronmens wh revoluonary applcaons. Especally n he ndusral secor CPS are an enabler for revoluonary mprovemens. CPS wll become par of all crcal componens n producs and machnery n order o enable ransparency. A every me sep complee nformaon abou he whole plan ncludng he locaon of producs, her nex needed process seps, he sae of every machne ec. s avalable and hus complee knowledge abou he acual sae of he plan s always gven. As CPS no only record hs nformaon bu also analyse hey allow parally auomaed conrol loops n plans and neworks o ncrease effcency. One example on plan level s gven here: The CPS of a producon sysem recognze a srong ncrease n ransporaon beween a surface qualy gae and s reworkng saon for a specal ype of produc (ype A). The CPS analyse hs nformaon and send a noce o he accordng surface fnshng machne. Therefore he machne s CPS wll deny he surface fnshng process for all producs of ype A and ask a worker for repar. Meanwhle all oher producs can sll be processed on he machne. Type A producs wll communcae wh oher surface fnshng machnes n he plan va CPS. So, hey can ge her needed surface fnshng process done by anoher machne. So, he CPS n he plan hus reduce he amoun of needed rework n an auomaed conrol loop Innovave Busness Approaches In order o ncrease robusness o exernal shocks a new undersandng of changeably s needed. The opmal mx of adapaons of he producon nework and he producon plan has o be found by negraed models. Frs examples are gven by Lanza and Peers [4]. Fuure approaches have o ake no accoun he whole exernal supply chan n hese approaches. In order o handle he complexy of such an approach new decenralzed decson makng models have o be developed, usng CPS. The conracs beween suppler and OEM wll change dramacally. Supplers wll be forced o gve complex warranes (nsurances) called Flexbly over Lfecycle Warrany (FLW) accordng o her own flexbly n delverng goods. On he oher hand OEMs share her forecass and all nformaon wh all parcpans of he supply chan n real me o avod bullwhp effecs. For nsance an auomove suppler promses o delver half of a reference amoun as well as wce as much whn one lfe cycle for one fxed prce. Consequenly, such nnovave busness models enable he praccal applcaon n ndusry and reduce complexy by decenralzed decson / conrac makng. The close parnershp enforced by such knds of rsk-sharng conracs s of crucal mporance n effcen supply chans. These consderaons lead o approaches regardng he macroscopc effec on he whole supply chan. However hese rsk-sharng conracs pose challenges o he suppler and he OEM. Boh companes have o be reconfgurable, flexble, ransformable and agle. So her nra-company nework has o be adapable. The nra-company nework (n he followng called nework) consss of raher ndependen ndvdual players. The so called players are dfferen producon workshops whch are placed a dfferen locaons n he global nework. The ndvdual decsons of hose dfferen players have effecs on he whole nework. Bu n whch case wll hese ndvdual decsons lead o a preferred sae of he nework? In order o regard hs non-rval queson a frs he decson suaon and opmzaon problem of he ndvdual players s regarded. 4. Inernal reamen of shocks In order o enable nnovave busness models as menoned n secon 3.2 plans and producon sysems have o become much more agle han hey are oday. Besdes flexbly o exernal changes plans also have o be robus owards nernal shocks (e.g. machne break downs or emporary unavalably of employees) o acheve hs degree of agly. Cyber Physcal Sysems are a promsng enabler n hs feld. The avalably of connuous nformaon a early mes sages of producon leads o more me o reac as knowledge of he complee suaon can be aken no accoun when plannng alernave producon. For he plannng of producon alernaves several nformaon on he gven sysem s sae, collecable va CPS, are needed e.g. he machnes saes, locaon of producs and her nex needed producon processes as well as esmaed repar mes. Gven hs daabase an effecve reschedulng can be used o denfy alernave producon possbles when nernal shocks occur. Fgure 1 gves an example of a raher flexble producon sysem organzed n a job shop manner. Besdes he dfferen processng secons also he dfferen ways hrough producon are shown for varous produc varees.

4 124 Gsela Lanza e al. / Proceda CIRP 7 ( 2013 ) Mllng Machnng Cenre Fg. 1. : Roues hrough regular producon Whle all machnes are workng as expeced, all producs wll follow hese gven roues hrough producon. As soon as an nernal shock occurs, e.g. a machne breakdown, hese roues canno be aken any more and dfferen producon alernaves have o be found, as can be seen n Fgure 2. Mllng Machnng Cenre Turnng Grndng Turnng Grndng Fg. 2. One possble reschedulng alernave gven he broken Machnng Cenre Those alernave producon roues can be found by reschedulng approaches. The needed reschedulng approach can be caegorzed accordng o Ayug e al [5] as dynamc, predcve-reacve and paral repar of schedules. Besdes he effec of sably also he ncrease n coss and he nework srucures have o be negraed no he new approach. However mplemenng he found reschedulng soluons s no always reasonable. Consderng a sudden machne breakdown he me and moneary expanses (e.g. adjusmen and reoolng of machnes) mplemenng a reschedulng soluon can be much hgher han wang ll he machne s repared (dependng on he consequences for all oher players n he nework). Besdes he bare mehod for reschedulng he expendure-esmaon and decson-makng mechansm of he assocaed reschedulng soluon are hus of crucal mporance. When decdng for or agans mplemenng reschedulng soluons several aspecs have o be aken no accoun. As menoned above no only producon coss are affeced bu also producon me and he consequences dependng on he curren workload of he nework. These facors have o be consdered when comparng alernave reacons on nernal shocks. Those alernave reacons can eher be dfferen reschedulng possbles whn he player s local producon sysem or he opon of wang for machne repar. In order o compare hese alernaves he menoned facors have o be regarded for each alernave. When consderng cos aspecs also he known coss of warranes of he new nework busness models have o be aken no accoun. Wang for machne repar can hus cause a ceran known amoun of penaly coss ha have o be pad o oher players n he nework. All players whn he nework opmze her decsons ndvdually o her own bes. They do no ake he whole nra-company nework no accoun. Consderng he dfferen reschedulng possbles a mahemacal model has o be developed whch gves he bes reacon on an nernal shock. Heren every possble adapon of he producon sysem (found by reschedulng) has o be consdered, as well as he opon wang for machne repar. Therefore, he sochasc varable of me-o-repar and her varaons have o be consdered as a decsve facor. So besdes he mere reschedulng problem a sochasc decson and opmzaon problem arses whch can be seen n formula (1). Index j s used for all producs. Index on he oher hand s used for producs ha are affeced by an nernal shock and hus could/should possbly be rescheduled. re_s_cos descrbe he reschedulng coss for produc. These coss depend on he dfference n me needed mn{ + {j/{}} {} effecs( re_s_cos ( j ) rs D,, a, b) + ( RT ) * p prod_cos(a, b) ousourcng } for he rescheduled producon and he regular planned rs) and on oher parameers (a,b) lke addonal ranspor needed. prod_cos are he addonal producon coss for he non-rescheduled producs. When mplemenng he reschedulng soluon for he producs ha are affeced by an nernal shock also he producon coss for he oher producs can rse. Consder a reschedulng soluon whch suggess o produce he rescheduled produc on a dfferen machne usng he pars already placed a hs new machne. In hs case he descrbed prod_cos derve from acves lke machne adjusmens needed n order o ge he machne back no s regular sae; supply of pars and componens whch were used whle producng (1)

5 Gsela Lanza e al. / Proceda CIRP 7 ( 2013 ) he rescheduled producs, ec. These coss depend on he same parameers (a,b) descrbed above. effecs are me sde effecs on all producs j n he producon sysem ha mgh have o wa for her producon processes j) because of he rescheduled produc. The aspec of producon delay has o be regarded separaely from he ohers aggregaed n he erm prod_cos because a producon delay can cause exernal penaly coss from he nework. D, (RT) s he dfference n delvery-me of he affeced produc f no reschedulng s mplemened. Ths delay wll hus depend on he repar me RT of he machne whch s a sochasc varable. p s he prce he regarded player has o pay o he nework coordnaor for every me-un of produc 's delvery delay. ousourcng are he coss for ousourcng produc o a dfferen player n he nework whch s an alernave o reschedulng of he player s own producon sysem. If a complee nework s regarded n conex of a reschedulng approach hs alernave possbly has o be regarded. 5. Exernal reamen of shocks Combnng he consderaons on he level of producon sysems and whole producon neworks ncreases he complexy bu bears he opon of achevng globally beer resuls. E.g. a hghly me-pressng produc canno be produced due o a sudden machne falure. Whn he local producon sysem no oher machne can process hs maeral wh he needed accuracy. If only he local producon sysem s regarded he produc canno be rescheduled and hus has o wa unl he machne s repared. Bu consderng he whole producon nework mgh have offered he possbly o process hs mepressng par n anoher plan. So boh possble levels of reschedulng have o be consdered: Frs he level of reschedulng whn he local producon sysems (e.g. usng dfferen machnes ha are placed a he same producon sysem, as can be seen n he upper par of fgure 3), second he nework level. Heren he produc s produced a a dfferen workshop whch s locaed somewhere else (lower par of fgure 3). The conemplaon of all producon sysems of a nework, however, provdes a huge scope of possble acons leadng o many dfferen possble roues of producon and hus led o a sgnfcanly hgher problem-complexy. The arsng opmzng problem s parly shown n formula 2. The gven objecve funcon descrbes he problem of a nework manager. From he pon of vew of a global nework here are dfferen coss ha have o be pad. In case of a delayed delvery o anoher player n he nework penaly fees have o be pad. Those fees are pad by he ndvdual players o he nework manager who wll pay he concerned player wang for he produc. However, he prce p he ndvdual players have o pay for delays dffers from he prce he player wang for he produc wll ge (p c ). The dfference n hese prces leaves some money a he nework manager whch s used o come up for sde effecs ha derve from he delayed delvery n he nework. 0 { player D player producs j * ( p ( p c ) prod_cos(a, b) + effecs( (2) The nework manager wans o lead he whole nework owards he globally opmal soluon and acs far. So no personal prof s ganed by he nework manager bu he oal coss n he nework are mnmzed. However, he opmzng problem of each player parly shown n formula (1) has o be expanded when regardng a whole nework. Much more npu facors have o be aken no accoun lke ranspor coss, dfferen wage levels ec. Ths hghly ncreases he complexy of he gven problem. Of crucal mporance s also he knowledge of he curren sae of each player n he nework e.g. he curren work load of each plan. M1 M2 M3 Fg. 3. Two levels of reschedulng: local producon sysem and global nework Opmzng a whole nework s hus much more complex han an solaed opmzaon problem of a sngle player, whch s shown n formula (1). In order o deal wh hs complexy a decenralzed decson approach s used. The nework shall be opmzed M1 j ))} M2 M3

6 126 Gsela Lanza e al. / Proceda CIRP 7 ( 2013 ) globally by he ndvdual opmal decsons of each local player. The conrol parameers lnkng he ndvdual opmzng problems of he players o he global objecve funcon of he nework are he prces. These sraegcally desgned prces could hen be fxed whn he nework by conracs smlar o he descrbed rsk-sharng FLW conracs. The gven prces wll lead o ndvdual reacons on nernal shocks ha can eher be on he level of local producon sysems (reschedulng whn a producon sysem or wang for repar) or on he nework level (reschedulng whn a producon nework). Due o he sraegc prces he ndvdual decsons wll fnally lead o he globally opmal nework s reacon. 6. Summary Ad-hoc reschedulng of global nra-company neworks and plans as well as new nnovave busness models are necessary o face shor economc cycles and shocks. Ths reschedulng approach helps o creae reconfgurable, flexble, ransformable and agle plans and neworks. Heren cyber physcal sysems wll enable new decenralzed decson makng and n dong so, reduce complexy and boos up he speed of possble reacons o nernal shocks (e.g. machne breakdowns) and exernal shocks (e.g. marke shocks). CPS provde real-me daa of he whole nework and hus help o fnd he bes reacon n erms of a rade-off beween nernal and exernal reacons on shocks. The decenralzed approach wll reduce he gven complexy of a whole nra-company nework as he opmzaon problem s dvded no several ndvdual opmzaon problems. Each workshop whn he nework wll solve s own less complex opmzaon problem. A regulaon hrough prcng sysems nfluences he ndvdually opmal decsons n a favored way for he whole nra-company nework. New Innovave Busness Approaches suppor hs new srucure. Componen supplers wll enrch her porfolo by a new bundlng of approaches ncludng warranes o her producs n erms of rsk prevenon (e.g. warranes for needed me o reac o marke changes or bolenecks). Thus leads o a new undersandng of he relaonshp beween cusomer and suppler on he way o a rsk-sharng parnershp n analogy o TCO warranes. References [1] Fleschmann, B.; Ferber, S.; Henrch, P.: Sraegc Plannng of BMW s Global Producon Nework; n: Inerfaces, Vol. 25, No. 3, S , [2] Sephan, H.A.; Gschwnd, T.; Mnner, S.: Manufacurng capacy plannng and he value of mul-sage sochasc programmng under Markovan demand; n: Flexble Servces and Manufacurng Journal, Volume 22, Numbers 3-4, Sprnger, S , [3] Leung, S.; Tsang, S.; Ng, W.; Wu, Y.: A robus opmzaon model for mul-se producon plannng n an unceran envronmen; n: European Journal of Operaonal Research, 181, S , [4] Lanza, G.; Peers, S.: Inegraed capacy plannng over hghly volale horzons; n: CIRP Annals Manufacurng Technology, Vol. 61, S , [5] Gulherme E. Vera, Jeffrey W. Herrmann, Edward Ln: Reschedulng Manufacurng Sysems: A Framework of Sraeges, Polces, and Mehods; n: Journal of Schedulng 6. S , [6] Akurk, M.S. and Gorgulu, E.: Mach-up schedulng under a machne breakdown; European Journal of Operaonal Research, 112 (1), S , [7] Gao, Y.; Dng, Y.; Zhang, H.: Job-shop Schedulng Consderng Reschedulng n Unceran Dynamc Envronmen; Inernaonal Conference on Managemen Scence & Engneerng, 2009 Moscow, Russa. [8] Tan, Y.; Aufenanger, M..: A real-me reschedulng heursc usng decenralzed knowledge-based decsons for flexble flow shops wh unrelaed parallel machnes; Indusral Informacs (INDIN), S , 26-29, [9] Dong, Y.; Jang, J.: Producon reschedulng for machne breakdown a a job shop; n: Inernaonal Journal of Producon Research, [10] Hao, X.; Ln, L.: Job Shop Reschedulng by Usng Mulobjecve Genec Algorhm; 40h Inernaonal Conference on Compuers & Indusral Engneerng, Awaj Island, Japan, [11] Ayug, H,; Lawley, M.; McKay, K.; Mohan, S.; Uzsoy, R.: Execung producon schedules n he face of unceranes: A revew and some fuure drecons; n: European Journal of Operaonal Research 161, S , [12] Church, L.K.; Uzsoy, R.: Analyss of perodc and even-drven reschedulng polces n dynamc shops; n: Inernaonal Journal of Compuer Inegraed Manufacurng, 5 (3), S , [13] Abumazar, R.J.; Sveska, J.A.: Reschedulng job shops under random dsrupons; n: Inernaonal Journal of Producon Research, 35 (7), S ; [14] Bng Wang, Xaomng Wang: Paral Reschedulng for Permuaon Flow-shop Schedulng Subjec o a Machne Breakdown; n: Proceedngs of h Asan Conrol Conference (ASCC), 2011, Kaohsung, Tawan. [15] Rong Dong, We-png He, Ya-je L, Wen-ru He: A Workshop Reschedulng Algorhm o Solve Producng Anomaly; n: Proceedngs of he 2010 IEEE Inernaonal Conference on Mecharoncs and Auomaon, 2010, X'an, Chna. [16] Acaech: Cyber-Physcal Sysems Innovaonsmoor für Moblä, Gesundhe, Energe und Produkon [3] Deep- Burn Projec: Annual Repor for Idaho Naonal Laboraory; Sep