# This example is used in a journal version of the IP paper. # The general idea is to model the machining and inspection processes # for a titanium aircraft engine bulkhead. Naturally it is a major # simplification. values: reward discount: 1.0 ###################################################################### # STATES # # The states consist of a number of components. First of all there is # a distinguishing absorbing state. The remaining 9 states are # comprised of two attributes, each of which takes on 3 possible # values. The two attributes, their values and the short-hand used to # give the states their mnemonic names are: # # Machined State # o Slab (SLAB) # o Rough Machined (ROUGH) # o Final Machined (FINAL) # # Material Quality # o Grade A (A) # o Grade B (B) # o Grade C (C) # # The material quality refers to both the presence/absence of defects # and the tolerances of the machined surfaces. # states: SLAB-A SLAB-B SLAB-C ROUGH-A ROUGH-B ROUGH-C FINAL-A FINAL-B FINAL-C DONE ###################################################################### # ACTIONS # # The actions consist of predominantly two classes. At each step # either a processing and an inspection technique is chosen. # # Inspection # o Ultrasonic for subsurface defects (UT) # o Liquid penetrant for surface defects (LP) # o Visual (VISUAL) # # Processes # o Machine the part (MACHINE) # o Paint/Anodize the part and ship it out for assembly (SHIP) # o Decide that the part is not salvagable or useable (SCRAP) actions: UT LP VISUAL MACHINE SHIP SCRAP ###################################################################### # OBSERVATIONS # # The observational information can either come from the processing # actions or the inspection actions. For the processing actions, # often one gets some information about whether some spurious event # might have caused the part to come under abnormal stresses (e.g., # broken cutter, dropped part). We break these down into three # possible outcomes: # # o NORMAL - nothing out of the ordinary happened during processing # o QUESTIONABLE - nothing particularly significant happened, but # things did not go exactly smoothly # o PROBLEM - there was a definite problem that occured during # processing the part. # # For the inspection outcomes there is an outcome for each # possible material quality: GRADE-A, GRADE-B and GRADE-C. # Grade A being nearly completely free of defects of any kind # while Grade B has minor defects and Grade C has fairly # major defects. # observations: NORMAL QUESTIONABLE PROBLEM GRADE-A GRADE-B GRADE-C ###################################################################### # TRANSITIONS # ######################### # Inspection Actions # # Inspection does not affect the state of the part (these are all # non-destructive tests). T: UT identity T: LP identity T: VISUAL identity ######################### # MACHINE Action # # The machining process can introduce defects, either through the # machining itself or from handling the part. Thus the part quality # can degrade as a result of machinining. # There is also a chance that the machining process could remove # a defect, but we ignore this case. # Note that machining a finished machined part is a bit odd, but # we assume that should it be chosen it can introduce defects # from the material handling phase. T: MACHINE # SA SB SC RA RB RC FA FB FC DONE #------------------------------------------------------ #SA 0.0 0.0 0.0 0.97 0.02 0.01 0.0 0.0 0.0 0.0 #SB 0.0 0.0 0.0 0.0 0.99 0.01 0.0 0.0 0.0 0.0 #SC 0.0 0.0 0.0 0.0 0.0 1.0 0.0 0.0 0.0 0.0 #RA 0.0 0.0 0.0 0.0 0.0 0.0 0.96 0.02 0.02 0.0 #RB 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.98 0.02 0.0 #RC 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 1.0 0.0 #FA 0.0 0.0 0.0 0.0 0.0 0.0 0.95 0.01 0.04 0.0 #FB 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.96 0.04 0.0 #FC 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 1.0 0.0 #DONE 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 1.0 ######################### # SHIP Action # # Shipping means the game is over and we proceed to the absorbing # state. T: SHIP : * : DONE 1.0 ######################### # SCRAP Action # # Shipping means the game is over and we proceed to the absorbing # state. T: SCRAP : * : DONE 1.0 ##################################################################### # OBSERVATIONS # ######################### # UT Action # # Ultrasonic tests are modelled as never detecting a part to be # worse than it is. The predominant problem here is that the # orientation of the defect can often render it imperceivable. # O: UT # NORMAL QUEST PROBLEM GRADE-A GRADE-B GRADE-C #-------------------------------------------------------- #SA 0.0 0.0 0.0 1.0 0.0 0.0 #SB 0.0 0.0 0.0 0.25 0.75 0.0 #SC 0.0 0.0 0.0 0.10 0.15 0.75 #RA 0.0 0.0 0.0 1.0 0.0 0.0 #RB 0.0 0.0 0.0 0.15 0.85 0.0 #RC 0.0 0.0 0.0 0.03 0.07 0.90 #FA 0.0 0.0 0.0 1.0 0.0 0.0 #FB 0.0 0.0 0.0 0.1 0.90 0.0 #FC 0.0 0.0 0.0 0.01 0.07 0.92 #DONE 1.0 0.0 0.0 0.0 0.0 0.0 ######################### # LP Action # # Since this liquid penetrant NDP inspection only is good for # surface cracks, it is most effective when the part is in the final # machine state. In the slab or roughed out stages, only severe # cracks could be detected, since small cracks may be removed by a # final machining phase. # O: LP # NORMAL QUEST PROBLEM GRADE-A GRADE-B GRADE-C #-------------------------------------------------------- #SA 0.0 0.0 0.0 1.0 0.0 0.0 #SB 0.0 0.0 0.0 0.99 0.01 0.0 #SC 0.0 0.0 0.0 0.97 0.02 0.01 #RA 0.0 0.0 0.0 1.0 0.0 0.0 #RB 0.0 0.0 0.0 0.95 0.05 0.0 #RC 0.0 0.0 0.0 0.90 0.05 0.05 #FA 0.0 0.0 0.0 1.0 0.0 0.0 #FB 0.0 0.0 0.0 0.15 0.85 0.0 #FC 0.0 0.0 0.0 0.05 0.10 0.85 #DONE 1.0 0.0 0.0 0.0 0.0 0.0 ######################### # VISUAL Action # # Like the liquid penetrant inspection, this is only good for # surface defects and is not nerely as good. The things you can # detect visually are usually of such a drastic nature, that the # detectabilktiy of the defect would make it immediately a CLASS-C # material. Thus, a CLASS-B material is not something observed # visually. # O: VISUAL # NORMAL QUEST PROBLEM GRADE-A GRADE-B GRADE-C #-------------------------------------------------------- #SA 0.0 0.0 0.0 1.0 0.0 0.0 #SB 0.0 0.0 0.0 1.0 0.0 0.0 #SC 0.0 0.0 0.0 0.8 0.0 0.2 #RA 0.0 0.0 0.0 1.0 0.0 0.0 #RB 0.0 0.0 0.0 1.0 0.0 0.0 #RC 0.0 0.0 0.0 0.5 0.0 0.5 #FA 0.0 0.0 0.0 1.0 0.0 0.0 #FB 0.0 0.0 0.0 1.0 0.0 0.0 #FC 0.0 0.0 0.0 0.25 0.0 0.75 #DONE 1.0 0.0 0.0 0.0 0.0 0.0 ######################### # MACHINE Action # # Machining the part in the rough state # consists of taking off a lot of material and # handling a part which is fairly heavy. Thus, you would imagine that # the rough machining process should have a higher rate of something # going wrong. However, though this is true, the final machined part # is much more delicate and the close tolerances makes it much more # suspectible to damage. Therefore there is roughly the same # likelihood of something going wrong, though these are usually for # slightly different reasons. We skew the probabilities a bit, since # something going wrong can be indicative of the part's quality # degrading. This model is a little too simple and it does not # properly capture the coupling between something going wrong in the # processing stage (a transition from good to bad) with the actual # observation. # O: MACHINE # NORMAL QUEST PROBLEM GRADE-A GRADE-B GRADE-C #-------------------------------------------------------- #SA 0.98 0.01 0.01 0.0 0.0 0.0 #SB 0.96 0.02 0.02 0.0 0.0 0.0 #SC 0.9 0.05 0.05 0.0 0.0 0.0 #RA 0.98 0.01 0.01 0.0 0.0 0.0 #RB 0.96 0.02 0.02 0.0 0.0 0.0 #RC 0.92 0.04 0.04 0.0 0.0 0.0 #FA 0.98 0.01 0.01 0.0 0.0 0.0 #FB 0.96 0.02 0.02 0.0 0.0 0.0 #FC 0.92 0.04 0.04 0.0 0.0 0.0 #DONE 1.0 0.0 0.0 0.0 0.0 0.0 ######################### # SHIP Action # # The observation we get for the ship action is not important, # so we set it to be the same for all states. # O: SHIP : * : NORMAL 1.0 ######################### # SCRAP Action # # The observation we get for the scrap action is not important, # so we set it to be the same for all states. # O: SCRAP : * : NORMAL 1.0 ###################################################################### # REWARDS # # The absorbing state is zero cost, but not specifying gives it this cost. ######################### # UT Action # # An ultrasonic test is fairly expensive. The more machining (and # hence surfaces) the longer it takes and the more it costs. # R: UT : SLAB-A : * : * -50 R: UT : SLAB-B : * : * -50 R: UT : SLAB-C : * : * -50 R: UT : ROUGH-A : * : * -200 R: UT : ROUGH-B : * : * -200 R: UT : ROUGH-C : * : * -200 R: UT : FINAL-A : * : * -350 R: UT : FINAL-B : * : * -350 R: UT : FINAL-C : * : * -350 ######################### # LP Action # # The liquid penetrant technique is not as expensive as the ultrasonic # technique, but still is not that cheap. Its price too is a factor # of how complex the geometry is, which is directly tied to the amount # of machining that has been done on the part. # R: LP : SLAB-A : * : * -20 R: LP : SLAB-B : * : * -20 R: LP : SLAB-C : * : * -20 R: LP : ROUGH-A : * : * -35 R: LP : ROUGH-B : * : * -35 R: LP : ROUGH-C : * : * -35 R: LP : FINAL-A : * : * -55 R: LP : FINAL-B : * : * -55 R: LP : FINAL-C : * : * -55 ######################### # VISUAL Action # R: VISUAL : SLAB-A : * : * -5 R: VISUAL : SLAB-B : * : * -5 R: VISUAL : SLAB-C : * : * -5 R: VISUAL : ROUGH-A : * : * -10 R: VISUAL : ROUGH-B : * : * -10 R: VISUAL : ROUGH-C : * : * -10 R: VISUAL : FINAL-A : * : * -15 R: VISUAL : FINAL-B : * : * -15 R: VISUAL : FINAL-C : * : * -15 ######################### # MACHINE Action # R: MACHINE : SLAB-A : * : * -5000 R: MACHINE : SLAB-B : * : * -5000 R: MACHINE : SLAB-C : * : * -5000 R: MACHINE : ROUGH-A : * : * -15000 R: MACHINE : ROUGH-B : * : * -15000 R: MACHINE : ROUGH-C : * : * -15000 R: MACHINE : FINAL-A : * : * -15000 R: MACHINE : FINAL-B : * : * -15000 R: MACHINE : FINAL-C : * : * -15000 ######################### # SHIP Action # # We assume a material cost of $10,000 is factored into the price of # the part, so this number reflects the price minus that material # cost. # A slab of any condition is immediately reckognizable as not # acceptable, so this will cost the company the material cost. # Although you could argue that they can still machine the slab, so # the cost is too much, I would think that the company's credibility # would suffer more than this loss for trying to ship unmachined # parts. Because this is not something that we # R: SHIP : SLAB-A : * : * -15000 R: SHIP : SLAB-B : * : * -15000 R: SHIP : SLAB-C : * : * -15000 # A rough machined part is no better than a slab to the customer. R: SHIP : ROUGH-A : * : * -15000 R: SHIP : ROUGH-B : * : * -15000 R: SHIP : ROUGH-C : * : * -15000 # This is the tricky part. The buyer has no way of knowing what the # condition of the part is without inspecting it themselves. We # assume that shipping a sub-standard part is very, very constly to # the company. Either the buyer detects this and the reputation is # marred or worse yet, the part fails in service and results in a big # scandal and loss of future revenues. We assume that shipping a # class B part is not as bad as shipping a class C part. R: SHIP : FINAL-A : * : * 45000 R: SHIP : FINAL-B : * : * -50000 R: SHIP : FINAL-C : * : * -100000 ######################### # SCRAP Action # # Scapping the part causes you to lose the material costs. Any extra # costs from processing will have already been accounted for. # R: SCRAP : SLAB-A : * : * -10000 R: SCRAP : SLAB-B : * : * -10000 R: SCRAP : SLAB-C : * : * -10000 R: SCRAP : ROUGH-A : * : * -10000 R: SCRAP : ROUGH-B : * : * -10000 R: SCRAP : ROUGH-C : * : * -10000 R: SCRAP : FINAL-A : * : * -10000 R: SCRAP : FINAL-B : * : * -10000 R: SCRAP : FINAL-C : * : * -10000