4.1 The port between sensor and controller

The information input to the microcomputer must be digital information that can be processed. The output type of sensor can be pided into analog variable, digital and switching value. There are three corresponding basic port modes as shown.

4.2 Symbolic representation of sensing and testing function

The symbolic representation of sensing and testing function is shown.

The input port of sensing and testing function units is used for testing some physical change parameter. The output port is for transformation information, which can be processed by control subsystem. A literal symbol is “test + parameter”. The parameter here denotes parameter information in the type of standard sensors, such as linear-displacement–angular-displacement,

etc. The type of ordinary sensors and standardized literal of testing parameters of mechatronic system is as shown in Table 5.The function carrier of sensing and testing function are various standardized sensors. We can query the type, working principles, parameter range and applied occasion of standardized sensors by use of sensing and testing function carrier base.

5 Symbolic representation of information processing and control subsystem

The information processing and control function is realized by a control subsystem. The function carriers of control subsystems are mainly microcomputer and various controllers. The input port is armed information from sensing and testing modular. The output is processed information needed to control and provide feedback to generalized executive mechanism.

6 Symbolic representation of functional relationship of mechatronic system

6.1 Symbolic representation of integration and fusion of the three subsystems

Energy flow, material flow and information flow connect three subsystem and function unit modulars inside the three subsystems. There are three basic flows in a mechatronic system. Energy flow is a connection flow bridging multiple disciplines. Information flow is mainly various control signals needed for information processing and control subsystems.

6.2 Symbolic representation of the interaction relationship among function units

In order to solve an overall function, different sub functions and function units belong to different disciplines or different function layers exist interaction relationship.

There exist five ordinary interaction relationships in the mechatronic system.

1. Enhance relation (denoted as E). The realization of one function can enhance another function. Their relationship is the Enhance relation.

2. Improvement relation (denoted as I). The realization of one function can improve the performance of another function. Their relationship is the Improvement relation.

3. Necessary relation (denoted as N). The realization of one function needs another function. Their relationship is the Necessary relation.

4. Preventing relation (denoted as X). The existence of one function can prevent another function. Their relationship is the Preventing relation.

5. Constraint relation (denoted as C). If one function takes a constraint, it limits and reduces the effectiveness action on another function. Their relationship is the Constraint relation.

The symbolic representation of these five function relationships is shown in Fig. 6. The Enhance, Improvement and Necessary relation words take positive action on scheme design. The Prevention and Constraint take negative action on scheme design and must append other function units to eliminate this side effect.

6.3 Logical reasoning relationship among function units

And, Or, Not form basic logical relationships, and complex logical relationship can be formed by combining these basic relationships.

6.4 Symbolic representation of a useful and harmful effects produced by function units

When implementing a function unit, the function unit may result in a useful or a harmful effect. The useful effect contributes positively to a design while the harmful effect contributes negatively to a design. Once a harmful effect has been identified, additional function units must be introduced to eliminate the harmful effect.