Method of Product Development Cost Estimating Based on ProA Hierarchical Decomposition Wen-hui Liu 1,2,Xiao-hui Zhao 2,Ya-wen Dong 2 1 School of Mechanical & Electrical,Northwest Polytechnic University, Xi’an,China 2 School of Mechanical & Electrical,Xi’an Polytechnic University,Xi’an,China (liuwenhui1976@163.com, xhuizhao@xpu.edu.cn,dongyawen231@163.com,) Abstract - To realize the cost estimating of product development, a estimating method based on Activity and its Process (ProA) hierarchical decomposition was presented integrating with product development process modeling. Cost attributes of ProA Input and Output Item and ProA conversion operations were firstly studied. Cost transfer between ProA Input and Output Item were analyzed in detail, and rules for cost estimating of ProA were also formulated. Finally, the method of the cost estimating was presented, and simulation based on Matlab environments was also conducted. and uses Activity-Based Costing to further research the cost attributes and cost transfer of ProA and establish a estimating method based on ProA hierarchical decomposition to better support cost decision-making of the product development project. Keywords- Activity-Based Costing, cost estimating, hierarchical decomposition, product development The product development process may be decomposed into a series of sub-process and the sub-sub-process…, each sub-process and sub-sub-process are composed of a set of linked activities which correspond to implementation process. There will be logical difficulty when using formalized method to define process and activity in decomposition course. To avoid ambiguity and solve the difficulty, Reference [12] proposes that integrating the process and activities as ProA and taking ProA as basic unit of the product development process and also makes detail study on ProA Input and Output Items, conversion operations and ProA hierarchical decomposition. This paper will take these concepts and the research results as foundation of the product development cost estimating. Using the definitions about ProA Input and Output Items and ProA conversion operations in Reference [13], ProA Input and Output Items and ProA conversion operations are summarized as follows with the need of cost estimating. Definition 1: ProA Inputs. The things that will be used up and transfer into output when the product development ProA is implemented. Definition 2: ProA Outputs. The things transform from inputs when using certain resources to implement ProA. ProA Inputs set: I. INTRODUCTION As to product development project, cost estimating is important for its technical and economic evaluation; product cost optimization and control and market pricing [1] . Along with the increase of individuation requirements which demand short-cycle and low-volume, the proportion of development cost in the product life cycle cost rises sharply [2]. At present, the researches about product cost estimating mainly take the product as the subject matter and roughly presume product development cost using the product attributes [3-6]. Because multi-projects are intercrossed concurrent, the cost estimating about the single product development project is difficult. In order to solve this problem, a mentality is proposed that collecting the research and development project cost and assigning it to the new product cost using Activity-Based Costing in Reference [7]. Based on Reference [8] in which improved Activity-Based Costing is used for estimating product development cost , Reference [9] analyzes the estimating method of activity cost driver with specific product examples and thus brings up to the product development cost. However, the estimation about product development cost is not only to obtain the product development cost. The manifestation of cost driver, cost transfer and value chain in the product development operation flow needs to model the development process [10,11]. The References [12, 13] take Activity and its Process (ProA) as basic unit of the product development modeling. That constructing product development process based on the ProA, which avoids ambiguity to the process and the activity, can better support dynamic programming of product development [13]. In view of this, this paper takes the product development process as the subject matter, quotes the concept of ProA II. ProA OF PRODUCT DEVELOPMENT AND ITS COST ATTRIBUTES A. Basic Dependent Concepts IN in 1 , ,in i , in p i 1,2, , p , 1 p 6 (1) ProA Outputs set: OUT out 1 , ,out j , out q j 1,2, ,q , 1 q 6 (2) The input and output items of a ProA are usually less than 6 [12, 13]. Definition 3: ProA resources. The roles which support the execution of ProA. ProA resource set : R r1 , ,rk , rm k 1,2, ,m;1 m 6 (3) Definition 4: ProA conversion operations. The process of converting ProA Inputs into Outputs using certain resources. It is expressed as: OUT T IN (4) The conversion operation j of ProA Output Item uses up resources to finish the conversion from IN to j out j , which actually includes a series of activities. Assume that the enterprise has implemented the activity cost management and sets up m activities according to the operation flow and product characteristics. These m activities are a1 ,as am and their cost driver rates are d1,ds dm . The product development group may determine activity drivers’ consumption l j ,l js l jm 1 respond to a1 ,as am that caused by j using experience or probability estimation[14] according to the enterprise’ historic data. Here, l js 0 and it indicates that this conversion operation does not consume the activity a m when l js 0 . Definition 5: ProA Granularity [13].It is a value that measure ProA activity size and the complexity of process to describe ProA decomposition degree in the product development process. Along with ProA hierarchical decomposition, the input-output relations among each sub- ProA and sub-subProA are clear gradually. The mutual quotation among internal input and output irems build relationship between one ProA and another ProA. So, mutual restrictions arise about ProA execution sequence and time. And also, it will cause cost transfer between input and output items of up-down stream ProA. Such condition exists that multiple ProA may take the same internal output item as their input 2 2 and item. As shown in Figure 1, ProA1,3 ProA2,2 2 as simultaneously quote a internal output item in ProA1,2 their input item. So, we consider the cost of this internal 2 and output item is also quoted and is shared by ProA1,3 2 . Thus, the cost between related internal input and ProA 2,2 output items maintain balance in the process of ProA hierarchical decomposition. Similarly, certain ProA output items are both external output items and internal output 2 items. Such as the output item in ProA 2,3 , one part of the cost is outputted, the other part flows into ProA 2,42 .As the product development progresses, each external input items cost and activity cost caused by convention operations are accumulated progressively and outputted finally. So, in the product development process, how the value on the activity chain accumulates and transfers in the enterprise is manifested. D. Cost Attributes of ProA a. Cost Attributes of Input Set The cost attributes of input item “ ini ”is expressed as B. ProA Hierarchical Decomposition: Set a product development project as ProA(0),the 2-9 sub-ProA(0) that decomposed are presented as ProA i1 , i R,1 i 9 , ProA i1 can be decomposed into ProA ij2 , i, j R,1 i, j 9 . Following the hierarchical decomposition of ProA, its input and output items and resources are correspondingly decomposed. Conversion operations completed by father ProA can be separately completed by its sub-ProA. As shown in Figure 1, ProA(0) Input , ProA i1 Input and ProA ij1 Input Items are called External Input Items, ProA(0) Output, ProA i1 Output and ProA ij1 Output Items are called External Output Items. External input I1 I2 I1 I2 I1 I2 I3 ProA11 2 ProA1,1 ProA(0) External output I3 1 ProA 2 2 ProA 2,1 2 ProA1,3 2 ProA 2,2 ACini Pini , N ini , C ini Pini is the original cost of (5) ini .When ini is a external input item, Pin is determined by the developer according to i the enterprise’ historic data and experience; When ini is a internal input item, Pin is determined by the original cost of i the quoted internal output item. N ini is cost distribution factor. When ini is communal or derives from the output item of certain ProA and also is simultaneously the input item of this ProA and the external output item of product development process, only part of the Pin flows into this ProA as input item cost i and its distribution rate is N in . In this case , the value of O1 i Internal output I3 2 ProA1,2 O1 : 2 ProA 2,3 Internal input N in is 0,1 ,otherwise, the value of N in is 1. Note that if certain ProA shares the same input item, the sum of each ProA’s N ini is 1. i i 2 ProA 2,4 Fig. 1. ProA Hierarchical Decomposition C. Cost Transfer between ProA Input and Output Items O1 C ini is the actual input cost of the input item, the cost that input item’s original cost Pin distributes into the ProA. (6) C in Pin N in i i i i The cost attributes of ProA input set is: p p i 1 i 1 ACIN Cini Pini N ini (7) b. Cost Attributes of Output Set The cost attributes of ProA output set “ out j ” is: ACout j Pout j , Nout j ,Cout j (8) Pout j is the original cost of output item, the cost value that determined by input item cost and conversion operations cost. N out is external output factor. When out j is only the j external output item, the value of N out is 1, which indicates j that its cost flows out completely as part of the ProA(0) output cost of product development project. When out j is only the internal output item, the value of N out is 0, which j process of converting the inputs to output item is called the cost contribution of input items to the output item. Along with the unceasing decomposition of product development process, ProA granularity and the number of ProA input items become fewer and fewer and the input cost is less and less. it is necessary to atomize ProA , neglect the correspondence between input and output items and only care about the cost of input and output items. Set the rules below: Rule 1 The cost contribution of input items to output items is consistent. That is: As to ini IN ( ini IN ini IN ),the cost j of in i is 1 q ( q is the number of output items). The rule leads to the expression of ProA output item cost: p ACout j C j AC IN q C j Cini q indicates that its cost flows into other ProA. When out j is not only the external output item but the internal output item, the value of N out is 0,1 ,which indicates the output j cost proportion of the external output item in this output item’s original cost Pout .The sum of N out and N in is 1, j j (14) i 1 According to the rule, the maximum error of cost contribution that ProA input item provides to output item is : max C in 1 qC in 1 1 q C in i N ini is the distribution factor of the internal input item that quotes this output item. Cout j is the actual external output cost of the output j contribution portion that in i contributes to out j in the cost i i (15) i With ProA hierarchical decomposition, the input item cost C in is less and less, the number of output items q also reduces, so the error becomes smaller and smaller. To reduce the estimating error, we should make the ProA granularity smaller to reduce the output items when ProA input item cost is higher. It proves that this error only affects the cost transfer between ProA and doesn’t influence the total cost of the product development. Rule 2 when several ProA quote the same input item, each ProA should share the quoted input cost according to its cost distribution factor. The rule can balance the incoming and outgoing of the cost between the related ProA input and output items of up-down stream in product development process, and achieve cost transfer and recurrence relations between ProA. i item. And, Cout j Pout j Nout j (9) The cost attributes of ProA output set is: (10) ACOUT ( APOUT , AWCOUT ) Here, q APOUT APout (11) j 1 q AWC OUT ACout j 1 means the original cost of ProA output set and APOUT AWCOUT means external output cost of output set. j j c. Cost Attributes of Conversion Operations The cost attributes of are: q ACPr oA C j (12) IV THE COST ESTIMATING METHOD BASED ON ProA HIERARCHICAL DECOMPOSITION j 1 Here, C j is activity cost that consumed by j . C j lj 1 , ,ljs , ljm d 1 , d s d m T m ljs (13) ds s 1 III COST ESTIMATING RULES OF ProA Definition 6: Cost Contribution. In order to get certain output item, all input items cost consumed in the Based on the recurrence element rule of cost estimating above, the process of cost estimating based on ProA hierarchical decomposition is described in Figure 2. a. Confirm the universe of product development ProA and input and output items As shown in figure 1, the process of product development and input and output items are decomposed hierarchically. The input and output items of the top layer ProA(0) are recorded as I 0 ( I01, I0 2,) and O0 O01, O0 2, . Decompose ProA hierarchically and confirm the universe of ProA and its input and output items Initialize the cost parameters Search from ProA(k) to find ProA whose input item cost attributes are obtained completely confirm the cost attributes of input item and input set ProA x,ky, confirm the cost attributes of ProAx,ky, convertion operations Color ProAx,ky, output item and output set by submodel 3 N j Y Fig. 2 The process of cost estimating based on ProA hierarchical decomposition As the decomposition of ProA(0) and its input and output items, the next layer ProA(1) is obtained and ProA(1)=(ProA1(1), ProA2(1),…, ProAn(1)).The sets of ProA(1) input and output items are and I 1 ( I11, I1 2,, I21, I2 2,) we can (1) sequentially decompose ProA to obtain different layers of ProA and its input and output items. Until ProA is no longer decomposed ,the bottom layer of ProA set is recorded as ProA(n) and its input and output items sets are I n and O n The universe of product development ProA is recorded as U ProA then U ProA =(ProA(0), ProA(1),…, ProA(k)). The universe of ProA input and output items are recorded as U I I 0 , I 1 , I n and U O O 0 , O 1 ,O n .As to ProA U ProA , ProA input set IN U I , ProA output set OUT U O , ProA input item ini U I and ProA output item out j U O . b. Initialize the cost parameters Firstly, using experience and probability estimation to estimate the activities required by each ProA conversion operation and the consumed quantity l j ,l js l jm of activity drivers according to enterprise’s historical data, so as to confirm the cost of ProA conversion operation j .Then, give the cost value of all external input items, 1 cost distribution factor N in of each ProA input item and i external output factor N out of each output item in the j process of hierarchical decomposition. 1 developer ,confirm cost attributes of output item . Then the cost attributes of ProA x,ky, output set are obtained by Confirm product development cost and the cost of each output item .Similarly, j to the estimated activity drivers quantity l j ,l js l jm and activity drivers rates d1 ,d s dm required by conversion operations. So, the cost attributes of ProA 1,k conversion operations are obtained by Equation (12). ④ By Cost Estimating Rules, according to external output factor N out of output item determined by the All cost attributes of ProA output set in ProA(k) are confirmed O1 (O11, O12,, O21, O22,) c. Confirm the cost attributes of ProA input and output items in term of Cost Estimating Rules ①Suppose the process of product development is decomposed to layer k , searching from ProA(k) to find ProA x,ky, whose input item cost attributes are obtained completely. ②confirm the cost attributes of ProA x,ky, input set by Equation (9). ③get the cost C of each conversion operation due Equation (11) and cost estimating rules. ⑤ ProA x,ky, output items are usually the input items of downstream ProA or output items of the whole product development process, based on this, we can confirm the cost attributes of input items of downstream ProA. ⑥ Judge that whether the cost attributes of ProA output set in ProA (k) are all confirmed, or return to ①. d. Product development cost When the cost of output set in ProA (k) is all confirmed, searching from ProA (k) to find all the ProA output items then sum the external output cost, that is the sum of ProA output set in ProA (k) and this sum value is the product development cost. Now, we get not only the product development cost but the cost of each output item. V SIMULATION EXAMPLE In order to carry out other assembly tasks, we need to test the flexibility of the one-way valve after one-way valve group of the car oil pump are assembled in oil barrel. The design of the testing part is the core of one-way valve tester. As shown in Figure 3, on the basis of design target, the development process model of one-way valve testing part is builded based on ProA hierarchical decomposition. As shown in Table 1, the activities and activity drivers in product development are setted according to the characteristics of business process and activity driver rates are calculated in term of resources consumed by activities in nearly one year. As shown in Table 2, the product development group and experts initialize the input and output items and conversion operations of the 12 ProA in the third layer of the hierarchical decomposition in Figure 3. According to this estimating method, the simulation model in Matlab environments for polychromatic sets recurrence element model is builded. The cost of product development process is estimated by the simulation model and the simulation result is shown is Table 3. Considering the case above, the cost estimating method of product development based on ProA hierarchical decomposition can be analyzed as follows: The estimating method is flexible. As the hierarchical decomposition continues, the estimating accuracy is promoted gradually. Based on this estimating method, the enterprise can know the cost of the product development and each output Design assignment Oil barrel assembly drawing Funds Design assignment Design assignment Oil barrel assembly drawing Design assignment Oil barrel assembly drawing Preliminary scheme Funds Schematic design Oil barrel assembly drawing ProA1(1) item, the organization can know well about how the value on the product development activity chain accumulates and transfers in the enterprise, and also the method can well support the cost analysis of operation process and the improvement of business process. The estimating method is based on the processoriented cost analysis and is useful for the cost estimating of the product life cycle and cost analysis of business process, thereby supporting the function cost analysis of the business process. Development of oneway valve tester ProA(0) Tester Detailed design and Components and parts trial-produce ProA2(1) Test the assembly Tester ProA3(1) Preliminary Measuring head and protector Measuring head design scheme and trial-produce Funds Fixture design and Fixtures Funds (2 ) ProA2,1 trial-produce Funds Gas circuit design and Gas circuit ProA2,2(2) trial-produce components ProA2,3(2) Schematic design ProA1 ,1(2) Drawings and technical Schematic Preliminary Measuring documents scheme head design design ProA1,1,1(3) ProA 2,1,1(3) Drawings and technical Customized Measuring head documents measuring head protector design protector ProA2,1,2(3) Funds Tooling requirements and routing ProA 2,2,1(3) Drawings and technical documents Funds Fixture material purchase ProA2,2,2(3) Measuring head protector ProA2,1,3(3) Measuring head material purchase Material Measuring head Funds manufacture ProA2,1,4(3) ProA2,1,5(3) Tooling requirements and routing Fixture design Test the assembly Measuring head Gas Gas circuit circuit components Gas circuit scheme Customized gas circuit design Funds ProA 2,3,1(3) ProA2,3,2(3) Fixture manufacture Material Test the assembly ProA 3,1,1(3) Fixture ProA2,2,3(3) Figure 3 The development process model of testing part based on ProA hierarchical decomposition TABLE I THE SET-UP OF ACTIVITIES AND ACTIVITY DRIVERS IN THE PROCESS OF PRODUCT DEVELOPMENT Activity codes Activity names Activity drivers Activity driver rates(Yuan/ Activity unit) a1 Discussion Task time 20 a2 Documentation Task time 20 a3 Drawing design Number of drawing 100 a4 Checking the drawing Number of drawing 30 a5 Process design Task time 20 a6 Process audit Task time 20 a7 Tooling preparation Task time 15 a8 Material purchase Material quantity 5 a9 Basic trial-producing Task time 18 a10 NC trial-producing Task time 250 a11 Assembling Task time 20 a12 Testing Task time 40 TABLE II INITIALIZATION OF THE COST PARAMETERS ProA Codes Input items Input items Cost External input Output Output items and their conversion operations Activities consumed by output items Tester ProA3,1,1(2) External Tester distribution factors item cost items conversion operations output factors O1,1,1 Ф1,1,1=(10,4,1,1,0,0,0,0,0,0,0,0) 0 I2,2,2-2=150 NULL NULL I2,3,2-2=5800 O2,1,1-1 O2,1,1-2 O2,1,2 O2,1,3 O2,1,4 O2,1,5 O2,2,1-1 O2,2,1-2 O2,2,2 O2,2,3 O2,3,1 O2,3,2 Ф2,1,1-1=(8,4,12,12,0,0,0,0,0,0,0,0) Ф2,1,1-2=(0,0,0,0,36,16,0,0,0,0,0,0) Ф2,1,2=(3,4,1,1,0,0,0,0,0,0,0,0) Ф2,1,3=(0,0,0,0,0,0,0,3,0,0,0,0) Ф2,1,4=(0,0,0,0,0,0,0,9,0,0,0,0) Ф2,1,5=(0,0,0,0,0,0,35,0,35,0,0,0) Ф2,2,1-1=(6,4,6,6,0,0,0,0,0,0,0,0) Ф2,2,1-2=(0,0,0,0,16,8,0,0,0,0,0,0) Ф2,2,2=(0,0,0,0,0,0,0,6,0,0,0,0) Ф2,2,3=(0,0,0,0,0,0,15,0,15,0,0,0) Ф2,3,1=(2,2,1,1,0,0,0,0,0,0,0,0) Ф2,3,2=(0,0,0,0,0,0,0,11,0,0,0,0) 0 0 0 0 0 0 0 0 0 0 0 0 NULL O3,1,1 Ф3,1,1=(0,0,0,0,0,0,0,0,0,0,2,2) 1 ProA1,1,1(3) I1,1,1-1,I1,1,1-2 1,1 I1,1,1-1 =0, I1,1,1-2=0 ProA2,1,1(3) I2,1,1 1/3 NULL ProA2,1,2(3) ProA2,1,3(3) ProA2,1,4(3) ProA2,1,5(3) I2,1,2 I2,1,3-1,I2,1,3-2 I2,1,4-1,I2,1,4-2 I2,1,5-1,I2,1,5-2 1/3 1,1 1/3,1 1/3,1 NULL I2,1,3-2=150 I2,1,4-2=150 NULL I2,2,1 1/3 ProA2,2,1(3) ProA2,2,2(3) ProA2,2,3(3) ProA2,3,1(3) ProA2,3,2(3) ProA3,3,1(3) 1/2,1 I2,2,2-1,I2,2,2-2 1/2,1 I2,2,3-1,I2,2,3-2 I2,3,1 1/3 1,1 I2,3,2-1,I2,3,2-2 I3,1,1-1,I3,1,1-2, 1,1,1,1 I3,1,1-3,I3,1,1-4 NULL TABLE III SIMULATION RESULT Output Items Output Items Cost (¥) External Output Factors of Output Items ProA2,1,2(3) O1,1,1 O2,1,1-1 O2,1,1-2 O2,1,2 410 1868.34 1108.33 1204.16 0 0 0 0 ProA2,1,3(3) O2,1,3 1369.16 0 ProA2,1,4(3) O2,1,4 1129.16 0 ProA2,1,5(3) ProA2,2,2(3) O2,1,5 O2,2,1-1 O2,2,1-2 O2,2,2 3392.49 548.34 1048.34 1228.34 0 0 0 0 ProA2,2,3(3) O2,2,3 2271.68 0 ProA2,3,1(3) O2,3,1 346.67 0 ProA2,3,2(3) O2,3,2 6201.67 0 ProA3,3,1(3) Product Development Cost O3,1,1 13355 1 ProA Codes ProA1,1,1(3) ProA2,1,1(3) ProA2,2,1(3) 13355 REFERENCES [1] Guo Chunming.Product Life Cycle Cost Estimation Based on Activity-based Costing(Ph. 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