Model Reference Adaptive Temperature Control of the Electromagnetic Oven Process in Manufacturing Process

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1 RECENT ADVANCES n SIGNAL PROCESSING, ROBOTICS and AUTOMATION Model Reference Adatve Temerature Control of the Electromagnetc Oven Process n Manufacturng Process JIRAPHON SRISERTPOL SUPOT PHUNGPHIMAI School of Mechancal Engneerng Suranaree Unversty of Technology Address: Nakhon Ratchasma 3 THAILAND jrahon@sut.ac.th Abstract: - Nowadays, the electromagnetc ovens are used for heatng the comonent assembly of electronc manufacturng. The control systems of the electromagnetc ovens are feedback control system and PID controller are used to control ther temerature. Ths rocess s an mortance rocess n electroncs manufacturng. The roblems of the electromagnetc oven are the accuracy of the temerature resonse when they are used n the long erod of tme. Examles of ther roblems are overshoot and hgh value of delay tme. When the over rsng of temerature occur, t leads to roduce damagng. The over temerature roblem s susected that be can taken from hyscal changng of the electromagnetc oven. Because of ths reason, PID controller arameters are not arorate wth a new condton. Therefore, the electromagnetc oven control system wll have low effcency. Ths aer resents the control method for any electromagnetc oven by usng Model Reference Adatve System (MRAS) to adjust the arameters of PI controller. An aroxmated transfer functon of the electromagnetc oven obtaned from closed-loo data by usng nonlnear least squares method and the otmzaton of PID controller desgn s demonstrated va gradent descent method. The exermental and smulaton results showed good erformance n actual oeratons. ey-words: - Control Theory, Resonse otmzaton and Model Reference Adatve System Introducton In the comonent assembly rocess of hard dsk drve manufacturng has rocess usng the adhesve wth attached comonents. The adhesve rocess needs to be cured by usng the electromagnetc oven that curng temerature s controlled between T - T o C for t s second. It s found that an neffcency of requred temerature control and the effect causes the damage of the roducts. In roducton lne, the temerature resonses of the electromagnetc oven are out of the temerature requrement and aroxmate 5 ercent of over shoot temerature. Ths roblem has cause from the unsutable PID arameters that are aled n the system. Ths effect decreases the effcency of temerature control. Therefore, ths research has resented to aly method of the model reference adatve system to control electromagnetc oven rocess. Cho J.Y. and Do, H.M.[] analyze both structure and comonent of the oerated rocess of oven by alyng Tungsten-Halogen lam to be heatng source. Lord, H. A. [] analyzes the heat transfer study wth heat conducton, heat convecton and heat radaton that occur nsde the oven. The research of Wonhu Cho.[3] studes the heat resonse of system and the mathematcal model for usng n controller system desgn of oven rocess. Cho Wonhu Cho, Thomas F. Edgar and Jetae Lee. [4] resented the closedloo dentfcaton of the wafer heat resonse by usng nonlnear least squares method to fnd the coeffcents of arameters n the mathematcal model of the nfrared oven rocess wth Tungsten- Halogen lam usng the closed-loo dentfcaton method that obtans from the research of Yeo, Y., won, T. I., Lee,. W. [5] and Pramod, S.,Chdambaram, M [6]. In an oven rocess, Cho, J. Y., Do, H. M., Cho, H. S. [8] arl J. Astrom, Bjorn Wttenmark [] aled adatve controller and Stehen, A. Norman,[9] resented otmzaton of the controller system. ISSN: ISBN:

2 RECENT ADVANCES n SIGNAL PROCESSING, ROBOTICS and AUTOMATION Mathematcal Model of the Electromagnetc Oven Process T a (s) - G c (s) P(s) T o (s) G (s) T(s) PI controller Electromagnetc Oven Fg. The closed-loo system wth PI-controller dagram of the electromagnetc oven rocess The electromagnetc oven rocess s closed-loo temerature control system wth PI- controller and has the electrcal current controller for electromagnetc lam. Insde the oven, there are thermocoules for erform temerature measurement. The mathematcal model of the electromagnetc oven rocess can be nvestgated va theory of heat transfer and system dentfcaton wth lnearzaton [9]. The closed-loo control system s resented n Fgure. The electromagnetc oven rocess has the delay tme so we can estmate transfer functon as ds To () s e = G () s = Ps () (s τ ) where Tdes () s - desred temerature, T() s - roduct temerature, Ta () s - ambent temerature, Ps ()- ower nut (lam), - gan, τ - tme constant and d - delay tme (). Adatve Control System Ths s an adatve control technque where the erformance secfcatons are gven n terms of a model. A bock dagram of the Model Reference Adatve System (MRAS) s shown n Fg..The MRAS s to create a closed-loo controller wth arameters that can be udated to change the resonse of the system. The outut of the system s comared to a desred resonse from a reference model. The control arameters are udate based on ths error. The goal of the arameters converges to deal values that cause the lant resonse to match the resonse of the reference model.the temerature control of the electromagnetc oven s desgned a closed-loo PI-controller wth MRAS. We can be aroxmated delay tme of the model reference ds e = ds where d - delay tme of the model reference Fgure. Block dagram of a MRAS The electromagnetc oven rocess s descrbed by Ys () bs bs b = () Us () as as a The transfer functon of the model reference s gven by Y m () s bs bs b = (3) U() s as as where b = d, b = d, b =, a = τ d, a = d, a =, b = d, b = d, b =, = τ d, = d and = s The PI controller s Gc () s = s Introduce the error Thus (4) e= y ym (5) ae && ae & ae = ( a ) && y ( a ) y& (6) ( a ) y& ( b b) u&& ( b b) u& ( b b) u where e&& = && y && ym, e& = y& y& m To derve a arameter adjustment law, we ntroduce the Lyaunov functon V(,, e e&, ) e e& ( ) = ( ) (7) where and - adataton gan For the functon to qualty as Lyaunov functon the dervatve dv dt must be negatve. The stablty ISSN: ISBN:

3 RECENT ADVANCES n SIGNAL PROCESSING, ROBOTICS and AUTOMATION requrement dctate that ee& ee &&& ( ) & dv = dt ( ) & By substtutng eq.(6)nto eq.(8), assume τ τ, and d d, we obtan (8) dv = e& dt ( ) ( & dy && y& du&& u& ) e& (9) ( ) ( & dy& y du& u) e& The arameters udates can be obtaned usng the followng relatons: & && & && & & () = ( dy y du u) e & ( & & )& () = dy y du u e We get dv dt Snce V s ostve defnte and the tme dervatve of the Lyaunov functon s negatve sem-defnte then V () t V ( ), e, e&, wll be bounded. = e& () 3 Exermental results The adatve algorthm of the electromagnetc oven rocess wth MRAS usng an adatve controller based on Lyaunov s Drect method. The arameter values of the model reference are = , τ = 3.53 sec and d =. sec. We have assumed the model reference so that the ercent overshoot for a ste nut s less than 5%, the settlng tme s less than 6 seconds and the rse tme s less than 4 seconds when.38 = =.3. The exerment test of the temerature resonse at 8 o C and 9 o C for ste nut wth PI-controller can be udated to change the resonse of the system when =.5 and =.. The ntal values for ths adjustment algorthm are =.38 and =.3. The frst exerment test consders the temerature resonse for ste nut at 8 o C. The trackng resonses curve and the model reference resonses curve for dfferent electromagnetc oven are shown n Fgure 3, 5. From Fgure 4 and 6, we see that the controller arameters do ndeed aroach ther best value as tme ncreases. Temerature( o C ) Cycle Cycle Model Resonse Exermental Resonse Fgure.3. Trackng erformance wth MRAS st electromagnetc oven.4.39 Cycle Cycle Fgure.4.Controller arameters Temerature( o C ) Cycle and st electromagnetc oven Cycle4 Model Resonse Exermental Resonse Fgure.5.Trackng erformance wth MRAS nd electromagnetc oven ISSN: ISBN:

4 RECENT ADVANCES n SIGNAL PROCESSING, ROBOTICS and AUTOMATION.4.38 Cycle Cycle Fgure.6.Controller arameters nd electromagnetc oven Notce that the temerature resonse of the frst electromagnetc oven n cycle exhbts long settlng tme (8.4 sec) and ntal temerature s 5 o C. After cycle 9 mrovng such resonse characterstc are desrable. The temerature resonse of the second electromagnetc oven n cycle erforms over 5.6 % of overshoot, long settlng tme (. sec) and ntal temerature s 34 o C. The resonse after cycle 9 corrects to the same model reference resonse. The detals of the temerature resonse at 8 o C are shown n Table. Table. The temerature resonse of the electromagnetc oven rocess at 8 o C Temerature resonse of st electromagnetc oven Maxmum Percent Rse Settlng tme tme (%) Cycle (C o ) (%) Temerature resonse of nd electromagnetc oven Cycle Maxmum (C o ) Percent (%) Rse tme Settlng tme (%) The second exerment test consders the temerature resonse to ste nut at 9 o C. Fgure 7, 9 shows the lots of the ste resonse of the electromagnetc oven rocess wth MRAS. These temerature resonse curves demonstrate that the desgn PI controller wth MRAS s accetable. The arameter values of adatve algorthm system are ndcated n Fgure 8,. Notce that the temerature resonse of the frst electromagnetc oven n cycle, exhbts long settlng tme (7.3 sec) and ntal temerature s 58 o C. The resonse of the lant converges to the resonse of the model reference at the cycle 6. The temerature resonse of the second electromagnetc oven n cycle, shows long settlng tme (8. sec) and ntal temerature s 53 o C. The cycle 9 n Fg.9 shows that the lant resonse converges very well. In summarzng, we show the temerature resonse detals at 9 o C n Table. Temerature( o C ) Cycle 5 5 Model Resonse Cycle 3 5 Exermental Resonse Cycle 6 Fgure.7. Trackng erformance wth MRAS st electromagnetc oven at 9 o C Temerature( o C ).4.4 Cycle Cycle Cycle Fgure.8.Controller arameters st electromagnetc oven at 9 o C Cycle Cycle Model Resonse Exermental Resonse Fgure.9.Trackng erformance wth MRAS nd electromagnetc oven at 9 o C ISSN: ISBN:

5 RECENT ADVANCES n SIGNAL PROCESSING, ROBOTICS and AUTOMATION Cycle Cycle Fgure..Controller arameters nd electromagnetc oven at 9 o C Table. The temerature resonse of the electromagnetc oven rocess at 9 o C Temerature resonse of st electromagnetc oven Maxmum Percent Rse Settlng tme tme (%) Cycle (C o ) (%) Temerature resonse of nd electromagnetc oven Cycle Maxmum (C o ) Percent (%) Rse tme Settlng tme (%) The temerature control of the electromagnetc oven wth MRAS s to drve the error ( e= y y m ) to zero. Ths does not necessarly mly that the PIcontroller arameters aroach ther correct values. Notce that, the exermental results ndcate that the temerature control of the electromagnetc oven n manufacturng rocess obtaned wth MRAS work as good control erformance n actual oeratons. 4 Concluson Ths aer has demonstrated the model reference adatve control method wth PI controller electromagnetc oven rocess. Adjustment algorthm uses to udate PI arameters of the system wth Lyaunov s Drect Method. In order to control the temerature resonse follow requred model reference. The results of the research resents that PI controller adjust for effcency of the lant resonse to track model reference. The model reference adatve control method can be aled to control the requred temerature resonse for any electromagnetc oven machne and roved the exstence of adataton laws whch ensure that the error equaton n MRAS usng an adatve controller based on Lyaunov s Drect method for an electromagnetc oven rocess s asymtotcally stable. ACNOWLEDGEMENT The authors would lke to thankfully acknowledge the research grant from Natonal Electroncs and Comuter Technology Center (NECTEC) and Suranaree Unversty of Technology (SUT). References: []Cho, J.Y. and Do, H.M., A leanng aroach of wafer temerature control n a rad thermal rocessng, system. IEEE Transactons on Semconductor Manufacturng, Vol.4, No.,,.-. []Lord, H. A., Thermal and stress analyss of semconductor wafers n a rad thermal rocessng oven, IEEE Transactons on Semconductor Manufacturng, Vol., No.3, 988, [3]Wonhu Cho., Temerature control and modelng of the rad thermal rocessng chamber, PhD. Dssertaton, Unversty of Texas at Austn, 5 [4]Yeo, Y.., won, T. I. and Lee,. W., An energy effectve PID tunng method control of olybutadene latex reactor based on closed-loo dentfcaton, orean J. Chem. Eng., Vol., No. 5, 4, [5]Ln, C. A. and Jan, Y.., Control system desgn for a rad thermal rocessng system, IEEE Transactons on Control System Technology, Vol. 9, Issue,,.-9. [6]Cho, J.Y., Do, H. M. and Cho, H. S., Adatve control aroach of rad thermal rocessng, IEEE Transactons on Semconductor Manufacturng, Vol.6,Issue4, 3, [7]Stehen, A. Norman.(99). Otmzaton of wafer temerature unformty n rad thermal rocessng, IEEE Transactons on Electroncs Devces, 99,.-46. [8]arl J. Astrom and Bjorn Wttenmark., Adatve Control. ( nd Edton), USA, Addson Wesley, 995 [9]Jrahon Srsertol and Suot Phungma, Closed-loo Identfcaton of Infrared Oven n HDD Manufacturng Process, Proceedngs of the 9 Chnese Control and Decson Conference, 9, ISSN: ISBN: