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Design of force sensor for Micro Friction Tester Based on qfd/triz/fuzzy integrated technology

with the intensification of competition, enterprises are eager to develop new products and technologies as soon as possible under the condition of limited resources to maintain their competitive advantage. However, the completion of an invention or innovation is usually regarded as the result of inspiration explosion, which may require a long exploration and hundreds of failures. Therefore, how to speed up the pace of product innovation, Improving the success rate of innovation has become the focus of attention and research by scholars all over the world. At present, some scholars have proposed some design methods, such as QFD (Quality Function Deployment), TRIZ (invention and creation principle), robust design, ad (axiomatic design), Taguchi method, functional method tree, design optimization, morphological methodology matrix, etc, But each method can only be used to solve the problems in a certain stage of product innovation design "Product design has to go through four stages: product definition, conceptual design, technical design and detailed design. Each stage has to go through a complex design process. The success of product design is closely related to the design level of each stage. Only by organically integrating various methods can we effectively solve the problem of innovative design. In this paper, a qfd/triz/fuzzy integrated model is proposed, and the corresponding algorithm is given for the micro friction tester." The design of the sensor shows the applicability and operability of the model

1 qfd/triz/fuzzy integrated innovation model

qfd/triz/fuzzy integrated innovation design model is shown in Figure 1. QFD is used to identify customer requirements and convert these requirements into product technical requirements. Then the conflict resolution principle of TRIZ is used to solve the contradiction between the design parameters in the process of product technical requirements, and the principle solution set is obtained. Finally, the original understanding in the solution set is evaluated, and the optimal design scheme is selected

Figure 1 qfd/triz/fuzzy integrated innovative design model

1.1 QFD quality function configuration method

qfd was proposed by Japanese scholars in the late 1960s. It takes customer demand as the core, transforms customer demand into product technical demand, establishes the relationship between user demand and technical demand, and makes the final product always meet customer needs. The house of quality (H) is the nerve center of QFD. Its structure is shown in Figure 2, The house of quality is a product information base, which contains all customer information related to new product development, and establishes the relationship between product characteristics and customer needs, so as to reduce the gap between customer needs and product manufacturers, so that appropriate products can occupy the market at the right time and at the right price

however, QFD can not solve the contradictions and conflicts in the process of technical design, and the 40 conflict resolution principles provided by TRIZ can make up for the deficiency of QFD. The combined use of QFD and TRIZ can obtain innovative product design solutions that meet the needs of customers and solve various technical contradictions

1.2 TRIZ's conflict resolution theory

triz (Russian abbreviation teorijz rezhenija izobreattel ski zadach) is a set of systematic and practical theoretical system for solving invention and creation problems and realizing technological innovation, which was constructed by tshuller of the former Soviet Union and a group of researchers led by him. The theory holds that: a large number of inventions face the same basic problems and contradictions, but different research fields. If we can sort out the hidden knowledge of these methods and form theoretical knowledge that can be applied to different fields, we can point out the correct direction for innovation, speed up the pace of innovation and avoid the waste of resources. This theory is very suitable for enterprises to solve the contradiction between product conceptual design and technical design. The technical conflict in TRIZ theory refers to that an operation leads to both useful and harmful results at the same time. It can also mean that the introduction of useful functions or the elimination of harmful effects leads to the deterioration of one or several subsystems or the whole system. Tshuller reduced the engineering parameters with conflicts to 39 (as shown in Table 1), established a 39x39 engineering parameter contradiction matrix, extracted 40 invention principles to solve these conflicts from 2.05 million patents, and established the corresponding relationship between the contradiction matrix and 40 invention principles, as shown in Table 2. In the process of product design, the problem is described as the conflict between general engineering parameters, and then the invention principle to solve the contradiction is queried from table 2, and the product is designed according to the improvement objectives pointed out in the principle

triz method can only give a set of principle solutions to solve conflicts. Only by studying the feasibility of each original understanding and comparing its advantages and disadvantages can the optimal scheme be obtained. This process is to optimize the design of counterfeit fire-resistant B1 polyurethane products. There are many design optimization methods, and the original understanding of the problem is extracted from the invention and creation thinking of experts in other fields. These principle solutions have great generality and fuzziness. At present, China has arranged seven major petrochemical industry bases, and the designers can only give fuzzy comments on the principle solutions, such as good and bad. Fuzzy mathematics is the most favorable tool to solve these fuzzy problems, Here we use the fuzzy analytic hierarchy process to screen the original understanding and get the optimal design scheme

1.3 fuzzy design optimization technology: fuzzy analytic hierarchy process

(1) establish factor set. Suppose the principle solution set is s= (S1, S2... SN), and each original understanding is evaluated by using the indicators A1, A2,... Am, then a= (A1, A2,... AM) is the evaluation factor set, and the indicator weight in the evaluation set is expressed by w= (W1, W2,... WM)

(2) evaluate linguistic variables, weighted linguistic variables and triangular fuzzy numbers

the determination of evaluation index weight and evaluation value is the key problem of fuzzy multi-objective evaluation. The evaluation of many indexes requires the scoring of experts, and experts often give some fuzzy evaluation information close to natural language. For this reason, the corresponding relationships among evaluation language variables, weighted language variables and triangular fuzzy numbers in Table 3 are designed

(3) determination of index weight

m experts are set to participate in the evaluation, and the evaluation language variables shown in Table 3 are given for each index weight in the index set. If the k-th expert gives a weighted linguistic variable to an index in the index set, the triangular fuzzy number of the weight WJ can be obtained according to table 3. According to the fuzzy decision analysis theory, the evaluation information of each expert is aggregated to obtain the total weight of the evaluation index

(4) determination of index fuzzy evaluation matrix

if the k-th expert gives evaluation language variables for an index BJ in the index set for the i-th evaluator, then according to table 3, the evaluation triangle fuzzy number

(5) fuzzy comprehensive evaluation

is used to obtain the comprehensive evaluation value r given the weight of each index and the triangle fuzzy number of each index

2 research on the design of force sensor of Micro Friction Tester Based on qfd/triz/fuzzy integrated technology

the micro friction tester is an important test instrument for studying the micro friction law. The force sensor is the key component of the micro friction tester, and its load and measurement range are in the order of micrometers and nanometers. For example, the friction display mirror FFM has a needle tip radius of about 50nm and a probe scanning area of 1 μ mX1 μ m. The load is NN, and the size of common micromechanical components is generally micron level or even smaller. When the current sensors require high measurement accuracy, their resolution and sensitivity are low, which often can not meet the needs of the system

(1) the house of mass drawn from the analysis results of existing force sensors is shown in Figure 3. From Figure 3, we can see that the most important technical contradiction is:

contradiction: material strength - material deformation

(2) the solution of "solving contradiction by using technical conflict" is shown in Table 4.

(3) evaluating the solution in the concentration by using fuzzy optimization technology

four experts are hired to evaluate the solution in the concentration of principles, and the evaluation indicators are three (see Table 5) : A1: stability; A2: sensitivity; A3: resolution. See Table 6 and table 7 for specific evaluation data. The final evaluation result is:

beam: s5>s6>s4>s1>s3>s2, so b=40 is selected μ m. L=35mm

cantilever beam: m1>m3>m4>m2>m6>m5, so b=100 is selected μ m. L=133mm

3 conclusion

based on the QFD requirements of product design, this paper analyzes the house of quality of the force sensor of the micro friction tester, selects the material strength and material deformation as the main technical contradictions of the design, obtains the principle solution set of the product innovation design problem, and uses the fuzzy method to evaluate the understanding of the application of the original BASF materials in the overall design of the vehicle body, so as to obtain the optimal size design scheme. When the signal processing circuit is amplified about 30000 times, the resolution of the force sensor is about 46 μ N. It meets the design requirements, which shows that the force sensor of micro friction tester designed by qfd/triz/fuzzy integration method has strong applicability. (end)

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