Naomasa Nakajima

Design and fabrication of light driven micropump

A laser-light-driven micromechanical pump for fluids has been designed and fabricated. The fabrication process consists of photolithography and anisotropic wet etching. The pump consists of an array of microcells with membranes that are actuated by a light-heated working fluid. These cells are covered by a thin glass plate with an 18- mu m gap that makes a flow channel. Actuation light input of approximately 11 mW per cell is required for operation. An operation frequency of 3 Hz is expected on the basis of the basic experiments made. Typical fluid pumping displacements are approximately 30 nl per cycle. It is noted that since this device operates in a reasonably low temperature range, there is no evidence of thermal influence being given to the human body.<<ETX>>

Direct and intuitive input device for 3-D shape deformation

Standard input devices such as a mouse and a keyboard in present computer-aided design systems do not provide users with direct and intuitive facilities for highly 3-D shape manipulation. To solve the problem, this paper proposes a new interface system for 3-D shape manipulation by adopting a real elastic object as an input device. By deforming the device with bare hands with a tactile feedback, users can manipulate a 3-D shape modeled and displayed on a computer screen quite directly and intuitively. A prototype with a cubical input device made of electrically conductive polyurethane foam is also presented.

Photoforming applied to fine machining

Photoforming refers to optical forming methods such as stereolithography, photomask layering, and the 1H process. In these processes, a special liquid resin is used as forming material and solidified by light exposure. The authors applied this method to making micromachines. A theoretical analysis including computer simulation of photon behavior in the liquid resin shows that sharp focusing is not required to achieve high precision, but controlling of light amount is important for a good result. It is proved that resolution can be within a few micrometers. Results of experimental forming demonstrate the possibility of making such precise structures. Some microscopic models with a resolution of 8 mm and some movable models were formed. It is suggested that this process can be applied to the construction of three-dimensional fine structures and precise mechanisms.<<ETX>>

Study on microengines: miniaturing stirling engines for actuators

Abstract This paper describes the micro Stirling engine, a miniaturized Stirling engine the length, width, or height of whose body measure no more than several centimeters. The steps taken both to establish the design concept and actually to produce a microactuator are discussed. Geometrical scale analysis and computer simulation are used to investigate how the design parameters change when the engine size is reduced. This analysis and simulation enable a micro Stirling engine with an approximately 0.05 cm 3 piston swept volume (equivalent ot the displacement of a gasoline is approximately 10 mW at 10 Hz. Problems of scaling down the engine to a maximum length of several millimeters are discussed.

Mechanism concept retrieval using configuration space

When designing mechanisms, making use of examples in past designs and handbooks should lead to cost reduction by promoting the sharing of parts and subassemblies among the products as well as reduction of time and effort. At present, however, the process of surveying design examples is left almost entirely to human designers and little computerised aid has been developed. We propose a computerised method of retrieving mechanism concepts from a library by specifying a required behaviour using qualitative configuration space as a retrieval index. First, mechanism concepts and their kinematics characteristics are described and stored in a computerised library using qualitative configuration spaces accompanined by additional information such as motion type and motion transmission direction. To retrieve mechanism concepts which realise specific kinematic behaviour, designers specify the required behaviour as timing charts of given input and intended output motions. Motion types, motion transmission direction, and motion speed dependence of the input and output motions can also be specified. Computer programs translate the required timing charts into required locus patterns in motion parameter space, and then available mechanism concepts to realise the behaviour are retrieved based on pattern matching between the qualitative configuration spaces and the locus patterns. The method is implemented as an experimental computer program written in Prolog and applied to simple mechanism design problems as examples to confirm the effectiveness of the approach.

Study on micro engines-miniaturizing Stirling engines for actuators and heatpumps

The authors present micro-Stirling engines as a new potential field of micromachine study. The micro-Stirling engine is defined as a miniature Stirling engine, smaller than a few cubic centimeters. The purpose of this study is to establish the design concept and to realize a microactuator and a microheatpump. By applying dimensional analysis and computer simulation, the authors investigated how design parameters change when the engine size becomes smaller. A micro-Stirling engine of about 0.05 cm/sup 3/ in a piston swept volume was realized. The output power is about 10 mW for 10 Hz vibration. Problems of miniaturizing the engines to the size of a few cubic millimeters are discussed.<<ETX>>

DO-IT : Deformable Object as Input Tool for 3-D Geometric Operation

In this paper, a new concept of an interface system for 3-D geometric operation using a deformable real object as an input tool is proposed. By deforming the tool with bare hands by tactile feedback, users can deform a 3-D shape modeled and displayed on a computer screen directly and intuitively. By adopting a free form deformation-oriented approach, the interface enables various types of 3-D shape operations using a rather simple input tool. A prototype of the deformable object as input tool (DO-IT) interface system using a cubic input tool made of foam rubber and strain gauges demonstrates the effectiveness and potential of the concept.

DO-IT: deformable objects as input tools

Standard input tools such as the mouse and keyboard do not provide users with a direct and intuitive means of 3-D shape manipulation. This study proposes a new concept of interface system for 3-D shape deformation using a deformable real object as an input tool. By deforming the tool with bare hands with a tactile feedback, users can manipulate a 3-D shape modeled and displayed on a computer screen directly and intuitively. A PC-based prototype system with a cubical input tool made of electrically conductive polyurethane foam demonstrates the effectiveness and promise of the concept.

A conceptual design environment for micromechanisms

This paper presents the use of a knowledge based system and a knowledge sharing environment to support the design of micromechanisms. Based on the experience of a design project, we discuss knowledge representation concerning the function and behavior for supporting functional decomposition. For the knowledge sharing environment, we have extended a finite element analysis system to allow the designer to perform analysis over the network.

Computer-aided design diagnosis for machines—kinematic model extraction from mechanisms

Abstract This paper presents a method for kinematic model extraction from a given mechanism as an approach to design diagnosis. A computerized method of extracting a kinematic model, which is usually expressed by a kinematic diagram, is proposed and illustrated with four mechanisms of 4–34 elements. Also verification of intended kinematic models, and prediction of element separation in faulty mechanisms were successfully carried out. As a unified expression method for the mechanism and kinematic model, the Composition Diagram is proposed in our study.