Isao Nagasawa

A design product model for mechanism parts by injection molding

Recently, design support tools have been used to improve the efficiency of design work. These tools support design verification at each design stage, and succeed to some extent in improving the efficiency of the design work. However, the management of scattered design information and data conversion have lately become difficult because designers often require two or more tools. In this paper, we focus on the detailed design of mechanism parts made by injection molding and used in precision consumer products. We propose a design product model which describes the detailed design of such parts. The model describes the mechanism parts based on sets of faces, which are basic units in design work. In this way, the model can express design information in both two- and three-dimensional forms. We also define the procedures used to operate the model. Finally, the effectiveness of this model is shown by applying it to an experimental system.

An Application of Assembly Structure in Welding Estimate of Welding Object in Manufacturing Design

Welding vessel objects such as heat-exchanger, oil-tank and other civil-used pressure vessels are comparatively large size products. Design works for such products not only concern with the geometric data, more important aspect is to treat with the design knowledge used in design process. But traditional CAD systems generally depend on shape-oriented approaches and pay less attention on the features of design and dealing with design knowledge. Therefore, there has been a considerable growth of interest toward knowledge-based design support systems. We have proposed a design object model for manufacturing design of welding vessels. In this model, the assembly structure of a design object is represented by the essential design elements and their dependencies. This paper discusses its application and focus on welding estimate of a welding object and dealing with design knowledge related.

The knowledge representation and programming for robotic assembly task

Presents a knowledge representation and programming method for robotic assembly tasks. The methodology is explained through robotic assembly tasks with position and force control. The state space of assembly objects is abstractly defined using a qualitative landmark which consists of the state of an object and a robot. The current state and sensor input determines the next robot action, and the state of a robot is made to lead to the goal state. These concepts are formulated by using a finite state automaton. The action sequence is defined based on the control hierarchy structure which consists of four levels (control primitive level, control skill level, skill level and task level). The complicated assembly task can be represented by product and concatenation of control primitives in a lower level and various tasks can be defined by adding new control primitives. In the paper, the concept of a CRS (constraint reduction system) is introduced for making a robot task program. The CRS is realized by extended Prolog. All the action and primitives are considered as a process and can be uniformly described by the reduction rule of the CRS.

An Assembly Structure using Functional Element for Product Assembly Sequence Generation

Themanagement of design information is been becoming more and more important, and considerable research is being carried out on the representation of design information of assembly parts. This paper describes the representation of an assembly structure, which includes the introduction of a functional element. By using this functional element, constraint of the assembly structure can be naturally described. The functional element is used to express relations among the parts, and a relation can describe constraints among assembly parts which interfere without touching. The relation includes an assembly method and is capable of describing both constraint and interference. We demonstrate that our representation of the assembly structure reduces the search space of the assembly sequence.

A knowledge-based system for process planning in cold forging using the adjustment of stepped cylinder method

We report on a knowledge-based system for process planning in cold forging. In this system, a forged product is represented as an aggregation of forming patterns that consists of cylindrical pillar parts. The basic principle of the inference method we propose is to adjust the diameters of neighboring stepped cylinders so that they are identical. Plural deformable process plans are generated using expert knowledge about working limits, die configurations, and metal flow. This system can eliminate ineffective plans by using the knowledge of how to combine plural forming patterns into a single process. Moreover, it can evaluate process plans and interactively select the optimal one by considering production costs, the forming load, the effective strain in the product, the equipment, and other factors. We applied this system to actual forged products. As a result, this system is widely applicable to various shapes and types of equipment and can improve both maintenance and operation.

Object modeling and design knowledge processing based-on assembly structure in manufacturing design of welding vessels

Welding vessel objects such as heat exchanger of power plant, oil-tank and other civil-used pressure vessels are comparatively large size products. Design works for such products concern with the geometric design data, more important aspect is to treat with design knowledge in design operations. However, traditional CAD systems generally depend on shape-oriented approaches and pay less attention on the features of design activities and how to deal with design knowledge used in design process. To solve such a problem, as an integrative frame to deal with the knowledge of design object and design process, there has been a considerable growth of interest toward the knowledge-based design support systems. We have proposed an object oriented design object model for developing knowledge-based manufacturing design system of welding vessel objects. In this model, assembly structure of a design object is represented by the combination of the essential design operation elements and their dependencies. This paper discusses the design object modeling in manufacturing deign of welding vessels as well as its application in welding estimate of a welding vessel and method of dealing with the design knowledge related.

Knowledge-based system for die configuration design in cold forging

We propose a knowledge-based system for process planning in cold forging. In our study, we had developed FORTEK-L (FORging Technology of process planning using Expert Knowledge for Layout), which is widely applicable to various shapes and types of equipment. In the next step, we have developed a knowledge-based die configuration design system, FORTEK-D (Die configuration design), which can generate suitable die configurations from layouts obtained from FORTEK-L. In the development of FORTEK-D, we have analyzed and reproduced the expert engineer’s thinking process during die configuration design. Moreover, we have formulated the data representation, inference method, and knowledge-base for use with this system. In accordance with the formulation, we have developed a prototype system. We applied FORTEK-D to actual forged products and obtained appropriate results. The knowledge using the basic principle is widely applicable to various shapes and on a variety of equipment. Therefore, the abilities to maintain and operate the system have been improved.

Multi-threading inside prolog for knowledge-based enterprise applications

A knowledge-based system is suitable for realizing advanced functions that require domain-specific expert knowledge in enterprise-mission-critical information systems (enterprise applications). This paper describes a newly implemented multi-threaded Prolog system that evolves single-threaded Inside Prolog. It is intended as a means to apply a knowledge-based system written in Prolog to an enterprise application. It realizes a high degree of parallelism on an SMP system by minimizing mutual exclusion for scalability essential in enterprise use. Also briefly introduced is the knowledge processing server which is a framework for operating a knowledge-based system written in Prolog with an enterprise application. Experimental results indicated that on an SMP system the multi-threaded Prolog could achieve a high degree of parallelism while the server could obtain scalability. The application of the server to clinical decision support in a hospital information system also demonstrated that the multi-threaded Prolog and the server were sufficiently robust for use in an enterprise application.

Design Verifications using Knowledge Representation Language KOSA

We focus on design verifications which can be interpreted as the relationships between inferior and superior characteristics in a model of design object. We are researching on a knowledge representation language and its programming techniques for tolerance analysis which is needed in design verifications. In this paper, the language is applied to some design verification. Design verification systems can be constructed using knowledge representation and programming techniques in the language. A designer who does not have knowledge of computers can easily put their knowledge into this system. A prototype system has been developed and applied to real world problems. The experiments show that this language has enough describability, maintainability and extensibility. We hope that our approach will have a positive impact on design verification systems.