Tsunenori Honda

Study on Automatic Determination of Assembly Sequence

Summary This paper describes the automatic determination of assembly/disassembly sequence of machine units from the assembly drawings. Firstly, based on an assumption that the sequence of assembly is the reverse of that of disassembly, connective relations between parts such as fit, taper contact and clamping contact are classified according to the degree of freedom of motion. From this, the rules which govern the sequence are derived. They are classified into two levels: one is to sort the parts into serial groups along which assembly proceeds, and the other is to select parts in a group, both of which are described in terms of the principal connective relations of parts. Secondly, a simulation system to generate the feasible disassembly sequence is developed which includes description of the rules, checking of interference and accessibility conditions. Through the case studies on spindle head unit, gear box, etc., the effectiveness of the algorithm is demonstrated.

3-D shape reconstruction for recognition of freehand machine drawings

An algorithm to reconstruct three dimensional geometries of machine parts based on the two dimensional data generated from two orthographic projection views of machine drawings has been developed, and implemented to a system for recognition of freehand written machine drawings that has been under research and development by the authors since 1984. For machine parts with geometrical elements of planes, cylindrical surfaces and holes, the system can generate the overall 3D shapes from the two orthographic projection views data under some restrictions. In this paper, the algorithm is shown with some test results. Furthermore, the evaluation of the computing time is discussed comparing the theoretical estimation with the actual measurement.

Pattern Recognition of Part and/or Workpiece for Automatic Setting in Production Processings

Summary A method of pattern recognition of part and/or workpiece for automatic setting applicable to the processings such as assembling, machining, clamping, etc. is proposed. A prismatic or polyhedral object is put at the recognition station equipped with a mirror, and both direct and mirror images are taken into a single picture by an ITV camera. Based on the picture points, the 3-dimensional coordinates of feature points or vertices of the object can be calculated when the relative position and posture of both the camera and the mirror are known. By utilizing the calculated coordinates and the connective relations of feature points, the geometric information on the shape, dimensions, and location of the object are reconstructed, and recognition of a specific or instructed portion of the object is possible. In this paper, the principle for calculating the 3-dimensional coordinates of feature points from the 2-dimensional coordinates of picture points in the projected direct and mirror images is described. The experiments by means of semi-automatic processings, in which the 2-dimensional coordinates of feature points in a projected picture are measured by eye-measurements, yielded reasonable results. Furthermore, the methods for detecting the feature points, solving the correspondence problem of feature points in the direct and mirror images and determining the geometric structure of the object are discussed.

A Flexible Robot Control System with Both Task-Level Language and Visual Monitoring

A flexible robot arm control system with both an Interpreter of a task-level robot programming language and visual functions for monitoring conditions of objects has been developed. In the system. programmers can make their robot control programs by use of the verbs with task-level meanings, for example, “stack-on”. “carry”, “lift”. etc., and have primarily no need to describe the coordinate values once the circumstance and the initial states of objects in the circumstance are described in the “circumstance program part”. Furthermore, for coping with unexpected states in the robot operation, visual monitoring of objects can be performed giving a command “VISION”, a reserved word “locate”, etc. A system including both the task-level language interpreter and visual monitoring functions utilising a CCD camera has been realized for a robot arm, and experiments have shown the effectiveness of the system.

Estimation of three‐dimensional motion based on multiple distributed Kalman filters

A new estimation technique for three-dimensional motion estimation from a stationary sequence of stereo images, the multiple distributed Kalman filter (MDKF), is proposed. As an application, separate estimations of three-dimensional motions of plural objects are attempted. In the MDKF, duplication is recognized from groups of feature points on the moving objects and primitive Kalman filters (PKFs) are constructed locally; then the three-dimensional motions of the objects are estimated independently by each of the filters performing the motion estimation. This provides multiplicity, which recognizes the duplicated definition of the feature points, and variance, which performs the local definition of the PKFs. By evaluating the dynamic characteristics of the feature points and the PKFs, robustness for the discontinuities such as hiding and appearance of the feature points is enhanced. Moreover, in order to detect the PKSs whose consistency of motion has collapsed (in the case of extending over objects with different motions or in the case containing false feature points due to false matches), a method based on a statistical hypothesis test which utilizes the estimated motion parameters is introduced. Finally, clustering is applied for integrating similar motions. The effectiveness of the proposed technique is shown by simulations and experiments using real images.

Development of Machine Part Data Model Consistent with Designer's Shape Description in CAD/CAM System

Summary This paper describes a new geometric data model for the CAD/CAM system in mechanical industry, in which the shape of a part is represented hierarchically in the application data model as well as in what is called boundary representation. The main features of the application data model are: (i) it preserves the method of the designers shape definition including the information of the production processings, (ii) it is defined basically as ‘gluing’ the component shapes of linearly and/or vertically swept plane figures, (iii) the boundary representation can be globally and locally generated in a systematic manner, and (iv) properties such as symmetry and repetition can be derived. The case study of 2%-dimensional machine tool parts has revealed that the rotational parts can be identified automatically and the data can be used effectively in NC software for turning

A Synthesis Method for Similar Texture Images based on Minute Shape Features.

A synthetic method for generating arbitrary number of not the same but similar texture images has been developed. The method includes processes to extract basic shape elements from texture images originating in actual objects, to select them to reappear the image features and to arrange them in an image plane. The authors have already proposed the shape-pass type filter bank assuming that the sensual impression mainly depends on minute shapes existing in the texture images. By use of nine basic shape elements, namely black/white-roof, black/white-line, black/white-snake, black/white-pepper, and cliff, natural texture images originating in actual objects have been characterized by feature vectors in a nine dimensional space. To generate arbitrary number of similar texture images, minute shape pieces are collected from original texture images and arranged so that the feature vectors may become locally similar to the original images. By the method, a number of similar texture images have successfully been generated, and the results of questionnaires on the synthesized texture images to universities students have shown the effectiveness of the method.

Motion Recognition for Forearm Using EMG Frequency Distribution.

This paper describes a development of a method for motion recognition using frequency distribution considering motion transition in order to build an exoskeleton robot system for assistance in rehabilitation. Firstly, a method of recognition based on calculation of differences in frequency distribution between template data and current one has been proposed. Additionally, two sets of parameters were assembled to deal with keeping stiffness in sustained action and compliance in motion transition. Furthermore, method for detection of motion transition has been proposed and implemented into the system. As the result, the recognition ratio has been successfully increased to eighty percent by using the above-mentioned method.

A Variable Frequency PWM Method for Over-rated Quick Driving of Robots.

The purpose of the study is to develop a method to control the armature current of the DC servo motors effectively and safely in the case of over-rated driving of the motors for realizing quick motion of robots. A method of variable frequency PWM (Pulse Width Modulation) has been developed both to suppress the rush current generated at the starting and to prevent the decrease of the effective value of the current. To apply the method to quick driving of a robot leg with three joints, the mathematical model with similar responses has been derived, and experiments on the model has been performed. The results have shown the effectiveness of the method.

Production, computers and humanity

Abstract Production is a process, as a matter of course, to generate useful products, in which energies, information and humans act on and deform materials. The essential factor is how to make and accept the information to control energies reliably based on human intentions. To fulfil the matter, to make the process an automatic system totally or partially is inevitable, but a problem of the interface between the system and humanity arise. In this paper, the essential meaning of the production process and to be automatic have been discussed, and some approaches of automatic systems for production shown. Finally, an autonomic-integrated system has been proposed as a system considering machines-humanity interfacing.