Editor | On 25, Sep 2001

Chih-Chen Liu, Ph.D. student
Department of Mechanical Engineering
National Cheng Kung University
Tainan, 701 TAIWAN
Lecture, Department of Mechanical Engineering
Far East College, Tainan, TAIWAN

Jahau Lewis Chen, professor
Department of Mechanical Engineering
National Cheng Kung University
Tainan, 701 TAIWAN

Abstract

The 40 inventive principles and contradiction table of TRIZ techniques are a good method for solving engineering innovative design problem with system contradictions. This paper describes an inventive design method for the designer to solve engineering innovative design problem without contradiction information by using TRIZ 40 inventive principles. Some examples will illustrate the usefulness and convenience of proposed approach.

Introduction

When a design engineer tries to solve an innovative design problem, it is usually a system incompatibility or conflict design problem. As the designer changes certain parameters of the system in his design problem, it might make other parameters bad. Traditionally, the design engineer makes compromise with this kind of contradiction situations and restricts himself on performing innovative design tasks. The TRIZ method [1-3] is an available tool for the designer to handle this conflict conditions during the innovative design problem solving process. One of the TRIZ techniques was developed in the former Soviet Union by Altshuller, who had analysis over 400,000 patents to build the contradiction table and 40 inventive principles [1-7] . For using this technique in innovative design problem solving, the designer needs to first find corresponding contradictions for his problem at hand. Next, the designer matches the meaning of each contradiction with two appropriate parameters from 39 engineering parameters that defined in the TRIZ contradiction table [8-9] . The designer can find 3-4 most frequently used principles for solving engineering innovative design problem from contradiction table when he confirms the parameters of contradiction for an engineering system. However, sometimes the designer only knows how to improve one parameter of this system, but doesn’t know or can’t predict the corresponding contradiction parameter of this system. Furthermore, for some contradiction conditions, TRIZ contradiction table doesn’t recommend any inventive principles. Therefore, the contradiction table is useless in helping the designer finding suitable inventive principles and solving his innovative design problem. There are several techniques in TRIZ that do not require a definition of a contradiction – the System Operator, the Ideal Final Result, and the 76 Standard Solutions all work without explicit definitions of a contradiction. This paper describes an inventive design method for the designer to solve engineering innovative design problem without contradiction information by using the 40 inventive principles. Some examples will illustrate the usefulness and convenience of proposed approach.

Improving “Accuracy of Measurement”

The CCD laser measured instrument can quickly and accurately survey complex 3D curved surfaces. However, it also has some limitations, such as the object’s color is red or black. In this situation, the light is absorbed; there is no true reflection from the measured object when a red laser is shot at the object, so an inaccurate image is formed. Figures 1 and 2 show estimated results of a red Kitty model. As can be seen in the figures, there are many defects. For improving this quality of measurement problem, we tried TRIZ method and found a corresponding improving parameter “accuracy of measurement”. However, this is only one parameter that we can find for improving our problem. It is very difficulty for us to discover the corresponding contradiction parameters for this problem. Hence, there was really no way to directly use TRIZ contradiction table to find inventive principles that would solve this problem.

Fig. 1. Result of measuring red Kitty model (data points) Fig. 2. Result of measuring red Kitty model (shading)

At first we tried to find ways to improve “accuracy of measurement” parameter with corresponding TRIZ inventive principles. It is tried to find possible problem solving techniques from those known inventive principles. In other words, we considered all possible inventive principles for improving “accuracy of measurement” parameter and examined them one by one based on the information of TRIZ contradiction table. As a result, some inventive principles have high frequency of appearances, such as #32 “change the color” (21 times), #28 “replacement of a mechanical system” (18 times), #6 “universality” (11 times) . . . etc. These results, in particular principles were seen more often, show to be a potentially effective problem solving technique. In addition, one can find other possible solutions with TRIZ contradiction table by looking from another angle of this problem to avoid parameter “accuracy of measurement” deterioration. Some inventive principles, such as #28 “replacement of a mechanical system” (17 times), #32 “change the color” (14 times), #26 “copy” (11 times) . . . etc., were found by this approach to be also a potentially effective problem solving technique.

Improving “accuracy of measurement” parameter is active problem trouble-shooting, moreover avoiding “accuracy of measurement” parameter deterioration is passive problem solving. No matter whether active or passive, both approaches have positive significance once the problem itself is formulated correctly. Putting them together, we obtained the following inventive principles, such as #28 (35 times), #32 (35 times) . . . etc. The inventive principle #32 “change the color” is very suitable in solving this problem. The quality of measurement was improved successfully as a result of the color of measured object (the Kitty model) was changed from red to yellow. The improved results can be seen in Figures 3 and 4. Another inventive principle #28 “replacement of a mechanical system” can also be another kind of feasible technique for this problem. Based on principle #28, this problem can be solved by using the contact type 3D measured instrument for measurement of the original red Kitty model.

Fig. 3. Result of measuring yellow Kitty model (data points) Fig. 4. Result of measuring yellow Kitty model (shading)

Single Engineering Parameter and Inventive Principles

Previous case study provides a method for the designer by using one engineering parameter to improve system performance. Moreover, it doesn’t matter whether or not the presence of contradiction parameter is known. First , this method examines all corresponding inventive principles associated with each “improving parameter” in the TRIZ contradiction table. Particular principles were seen a number of times. This situation can be explained as that the inventive principles will make improvements to a certain “improving parameter” in the system, possibly corresponding with other “avoiding degeneration parameter” types. Hence, for certain inventive principles appeared more often, indicating that it is a good one to try in solving innovative design problem.

Next, the same procedures were applied to each “avoiding degeneration parameter” in another dimension of the TRIZ contradiction table. The corresponding inventive principles were examined and accounted for their number of appearances. The use of those principles by the designer means that it can improving a system’s parameters and can avoid the deterioration of certain “parameters” simultaneously. As before, certain inventive principles appeared many times show that using those principles will give the designer a good try to solve innovative design problems.

Finally, combination of both parts together and summing up the number of appearances of all of the principles constructs a table for single engineering parameter and inventive principles, as shown in Table 1. The vertical axis is the TRIZ 39 parameters that the designer wanted to improve. The horizontal axis shows the frequency of appearances of each parameter’s corresponding principles. Table 1 classifies inventive principles into different ranks, such as A (more than 19 times), B (between 16 to 18 times), C (between 13 to 15 times), D (between 10 to 12 times), E (between 7 to 9 times), F (between 4 to 6 times) and G (between 1 to 3 times), according to the number of appearances in the contradiction table for each parameter. Those principles appearances most frequently (ranked at A, B, or C in Table 1) will have a better chance at success in solving inventive design problem. Therefore, the designer can solve engineering innovative design problem without contradiction information by choosing suitable TRIZ inventive principles based on information in Table 1.

Table 1. Table for single engineering parameter and inventive principles

Examples

1. First Example

The first example is the research methodology of this study. The aim of this paper is to develop an inventive design method to solve innovative design problem without knowing its contradiction information by using TRIZ inventive principles to improve the system’s engineering parameters or solve the engineering innovative design problem. The authors hope to improve or modify parameter “convenience of use” in the TRIZ contradiction table. Three principles associated with the “convenience of use” parameter with the highest appearance rates were found from Table 1. According to the order of appearance rate, they are #01 “segmentation”, #13 “inversion”, and #02 “extract”, respectively. These three inventive principles are exactly the same approaches as what the authors used to produce Table 1 and the TRIZ inventive design method without contradiction information. If authors could have used Table 1 at the beginning of this study (it didn’t existed at that time) to solve the problem mentioned above, then we would have greatly decreased the time and energy spent through trial and error method.

2. Second Example

Beverage cans are daily necessities in the modern world with lots of uses. The designer wants reduce the consumption of cans and lower the cost of production and environmental impact burden. One of the contradictions discovered by the designer [9] is the improving parameter of “length of nonmoving object” in conflict with the avoiding deterioration parameter of “tension/pressure”. From TRIZ contradiction table, there are three corresponding inventive principles:

#01 “segmentation” (breaking the cans surface by crushing it under pressure),

#14 “spheroidality” (the top of the can is assembled with curved lines and not straight ones), and

#35 “transform the physical/chemical state” (the material is made of higher intensity steel alloy).

Looking at it another way, the designer only have the concept of reduced can consumptions and he doesn’t know the possible deterioration contradictions. Based on the “length of nonmoving object” parameter, the designer can find the corresponding first five inventive principles from Table 1 as follows:

#35 “transform the physical/chemical state”,

#28 “Replacement of a mechanical system”,

#14 “spheroidality”,

#26 “copying”, and

#01 “segmentation”.

Inventive principles #35, #14, and #01 are the same as the principles come from traditional TRIZ method [9] . Therefore, even though the designer doesn’t know the system’s contradiction information, he can still use Table 1 to find suitable TRIZ inventive principles to solve his own innovative design problems. Furthermore, inventive principles #28 and #26 may give the designer other opportunity to find good solution approaches for his inventive design problem.

3. Third Example

The design purpose of the product “early stage of warning light” is to strengthen the warning function. The system parameter to be improved is “brightness”. By using Table 1, one can find three corresponding inventive principles:

#19 “periodic action” (change the lights flashing style),

#32 “change the color” (change the light’s color to red or yellow), and

#01 “segmentation” (add a lot of little lights around the edge of the sign).

4. Fourth Example

The contradiction condition for “smart car” design problem [10,11] is “small cars have convenient size but can’t absorb the energy of impact”. Although every designer hopes to design compact cars that are convenient for urban use (for example: easy parking or taking up less road space), there is fear that a small car will not be able to stand up to the impact by a traffic accident, particularly that the engine might injure the passengers.

In this example, the designer wants to improve the cars usage of road space, especially engine and engine compartment size. That is to say, to improve the “area of moving object” parameter (during a collision the engine and engine compartment are considered moving objects). The first two corresponding inventive principles for this parameter from Table 1 are #15 “dynamicity” and #17 “shift to a new dimension”. These two principles match the best solution strategies on Reference 11.

Conclusions

There are several techniques in TRIZ that do not require a definition of a contradiction – the System Operator, the Ideal Final Result, and the 76 Standard Solutions all work without explicit definitions of a contradiction. The present paper described an inventive design method for the designer to solve engineering innovative design problem without contradiction information by using the 40 principles. A single parameter inventive principles table (Table 1) was established in this study. This table is very useful for the designer in situations where it is unknown whether there is a contradiction and some parameters need to be improved. When the designer uses Table 1 to solve his innovative design problems, he should use the top of the list of the principles in Table 1 in order to be faster and more successful, but there is no guarantee that it is the best. The successful examples demonstrate the effectiveness of proposed method. Especially, as seen in the explanation of first example, this paper uses TRIZ methods to solve problems of TRIZ (innovative design problems without contradiction information).

Acknowledgements

This study is supported by a grant from the National Science Council, Taiwan, Republic of China, grant number: NSC89-2212-E006-169.

References

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