This article is devoted to the method of system
model improving by means system complexity reduction. The last one is based on
TRIZ function analysis and trimming. Suggested method may be used for new
development and for improving of existed system. As well, the suggested
approach is illustrated by the industrial case study.
The present paper is considered to the
function-based method of the design improvement and the development.
According Ullman, 75% of the product cost is defined on the conceptual stage 1. It means this stage is extremely important in the product
life-cycle. In this case, the usage of the systematic methods on this stage is
very useful for the design development and the improvement.
There are several systematic
approaches, such as the Axiomatic Design 2, USIT 3, TRIZ 4 etc. In this paper the TRIZ methodology is used for the
development, because it is easy to understand, to use formal approaches and
inventive tools and, as well, this methodology is widely used both in
science and in industry 5–7.
TRIZ, in Russian –
Theoria Resheniya Izobretatelskih Zadech, or The Theory of the
Inventive Solving, is the inventive method proposed by the soviet
inventor Genrih Alshuller (1926-1998) in 1956 8. He studied about 40000 patents and drew out the formal processes
for some new ideas of the generation and the technical evolution trends. Such
methods have 40 inventive principles, contradictions, ideality, and patterns of
This paper is devoted to the modern TRIZ
tools, such as, the Function analysis and the Trimming 9. The last one is a formal method for the system development and the
improvement, based in the system complexity reduction. Different
types of this tool are used for the patent-around design 10, the system improving 11 and to receive new design patterns 12. The improved method of the trimming is used for the
system improvement and the development in the formal manner in this paper.
Meanwhile the function analysis is used as the input to the trimming.
Existed trimming methods use formal rules
for the system step-by-step improving 10, 11, 13. Functions are independent in these approaches and authors did not
use the formal ranking index to define the function importance in the system.
Unlike existed methods, the new one takes into account the relation between
functions and elements. In this case the function analysis step is improved and
a new operation “creation and analysis of the Function interaction matrix” is
added before the trimming step. This improvement highlights the “function
streamlines” in the system. It means the functions are grouped in the sets.
This idea permits to automate the trimming algorithm.
This paper remainder is structured as
follow: the section 2 is devoted to the states-of-the-arts, the section 3 is
considered to the method description, in the section 4 the industrial case study
illustrates the presented method, section 5 consists of the discussion and the
finally, conclusions and the further development are presented in the section 6.
The functional part of the method is based on
TRIZ function analysis. There are several types of the function presentation of
the system, such as the Functional Flow Block Diagram (FFBD) 14, the Functional Analysis System Technique (FAST) 15, the Integrated Computer Aided Manufacturing DEFinition for
Function Modeling (IDEF0) 16, etc. All these methods use the function approach for the system
presentation. For example, the FFBD is the function-oriented approach based on
the sequential relationship of all system functions. FFBD develops a system
from the top to the bottom and it proposes the hierarchal view of the functions
across the series of levels. The aim of each one is to identify a single task
on a higher level by means of the functional decomposition. In comparison with
FFBD, the Functional Analysis System Technique (FAST) diagram focuses on the
product functions rather than its specific design. There the system is
presented in a tree structure where each function is presented in a verb + noun
format. Also, these methods
used static approach in function analysis. It means number of elements and
functions, relation between elements are time independent and didn’t change in
time. On other hand,
many of TRIZ practitioners point out the need to clearly identify problems at
each systems level, and to solve them separately. Such a goal was achieved by
integrating well known models and instruments for the system description and
the function representation. O. and N. Feygenson also suggest the Advanced
Function Approach in the Modern TRIZ 17 where they add some
steps like “Indicate the place the function is performed” and “Indicate the
time the function is performed”. That approach received its further development
in 18 by Litvin et al. with
the research in the application history and the evolution of Function
Analysis. The research indicates that
the next logical step for the Function Approach enhancing is the introduction
of two parameters: “time of performing a function” and “place of
performing a function”.
In contrast to FFBD and FAST, the TRIZ
function modeling takes into account the physical interaction between the
system elements and the type of this interaction. There are four interaction types
– useful, harmful, insufficient or excessive. In this approach, the system is
presented by using the component and function views together. Therefore, it is
possible to create a new design pattern and to make a new design based on the
Second part of the method consist trimming.
This is a formal process to improve system model using system complexity
reduction. There are different approaches in this case. For example, Miao Li’s
method 10 is used in patent around design. It takes into account an each
element importance. Gen3 method 13 is used for the design improvement and development. This one uses
the formal functional approach to rank the importance of each function in the
system. The presented approach combines and supplements these methods, also
collects the previous works in this domain.