Tadataka Konishi

New laser rangefinder for three-dimensional shape measurement of specular objects

We describe a new laser rangefinder for measurement of the shapes of specular objects. In many industrial contexts, objects with both Lambertian surfaces and specular surfaces are often manipulated. However, ordinary laser rangefinders usually cannot be used to measure specular objects. We propose a laser rangefinder for the measurement of specular objects based on a new idea in which the incident angle of a light-stripe upon the image sensor is limited through the use of a special light device. The concept of this rangefinder involves the application of triangulation to specular objects, which enables measurement of the shape of specular objects as well as Lambertian objects. We designed and built a prototype light-stripe projection rangefinder based on these principles. Experiments using the rangefinder successfully demonstrate the rangefinders accuracy. The proposed rangefinder is a promising tool for the performance of many common industrial tasks including measurement of the shapes of polished metal and the inspection of soldered joint surfaces.

Knowledge acquisition method for conceptual design based on value engineering and axiomatic design theory

Abstract A method for acquiring conceptual design knowledge in physical systems is proposed and implemented based on EBL (explanation-based learning), ‘value engineering methodologies’ and ‘axiomatic design approaches’. In this method, the structural features of designed objects are analysed to yield a systematic explanation of how they function and attain their design goals and why they are used for attaining the goals. The ‘how’ explanation results in a generalized version of the functional diagram used in value engineering from which various levels of general design knowledge can be extracted. The quality of the extracted knowledge is then discussed with reference to its mode of acquisition. The ‘why’ explanation yields a deeper understanding of the designed objects from which we can extract meta-planning or strategic knowledge for selecting rational plans from among other possible alternatives. This explanation is obtained by regarding the object in question as being the result of strategically rational decisions and actions which are subject to the ‘design axioms’.

A new position sensor for high-speed measurement of multiple points

A high-speed measuring system of multiple points is becoming an important issue in many industrial applications. Therefore, the development of a high-speed position sensor is an important issue. However, conventional sensors such as CCD(charge-coupled device) and PSD(position-sensitive detector) are insufficient to apply to the high-speed measurement of multiple points. We propose a new position sensor for high-speed measurement of multiple points. The proposed sensor features a single scanning detecting method of multiple points by parallel processing technique and design of the sensor by analog circuitry, which makes high-speed measurement of multiple points possible. The designed sensor system realizes both high-speed performance and high accuracy.

Range imaging system with multiplexed structured light by direct space encoding

Since practical multiplexed structured light systems currently available use plural light patterns or different illumination conditions to ensure a high reliability, their fast performance is impaired. This paper describes a fast, highly reliable range imaging system with a multiplexed structured light system that uses a direct space encoding approach while using only a single light pattern. Unlike a conventional encoding approach, the proposed approach is unique in that it encodes object space through the use of a special optical system which consists of field stops, plural lenses, and shield masks, rather than a light pattern. The theoretical considerations and experimental results demonstrate that the proposed approach is effective for a highly reliable, fast, accurate range imaging system.

Position and posture measurements and shape recognition of columnar objects using an ultrasonic sensor array and neural networks

A new method for measuring the position and posture (pose) and recognizing the shape using ultrasonic wave sound pressure signals and neural networks is proposed. In most of the past methods of this kind, the characteristic quantities have been based on either time of flight methods or acoustic holographic methods. In these methods, measuring and recognizing the width and depth directions simultaneously with a high resolution has been difficult in principle. In this paper, the problems of the past methods are resolved by changing the viewpoints by using criteria such as the peak values of the penetrating and reflecting waveforms, their positions, their deflection points, and their intervals when ultrasonic waves are directed onto a measured object, as characteristic quantities given to neural networks. In addition, a prototype measuring and recognizing system implementing the proposed scheme is constructed by introducing a circuit for detecting the peak positions of the sound pressure signal distribution waveforms with high resolution. The experimental results are satisfactory in position measurements and shape recognition, and confirm that the method is applicable to rectangular prisms and the like. It is shown that the position and pose measurements and shape recognition can be realized with high resolution in both the width and depth directions by this scheme, and that the proposed method is very effective when applied to position and pose measurements and shape recognition and the like ultrasonically.

Coevolutionary GA with schema extraction by machine learning techniques and its application to knapsack problems

The authors introduce a novel coevolutionary genetic algorithm with schema extraction by machine learning techniques. Our CGA consists of two GA populations: the first GA (H-GA) searches for the solutions in the given problems and the second GA (P-GA) searches for effective schemata of the H-GA. We aim to improve the search ability of our CGA by extracting more efficiently useful schemata from the H-GA population, and then incorporating those extracted schemata in a natural manner into the P-GA. Several computational simulations on multidimensional knapsack problems confirm the effectiveness of the proposed method.

A simultaneous high-speed measuring system of multiple points

We propose a simultaneous high-speed measuring system of multiple points based on new scanning method of sensor array. The system has following two features; (1) to detect the peak of outputs by means of parallel processing technique, (2) to interpolate between outputs of CCD by analog circuit. We constructed a prototype measuring system with discrete circuits. Prototype system demonstrates that the proposed system is effective for the simultaneous high-speed measurement of multiple points.<<ETX>>

A new fast rangefinding method based on a non-mechanical scanning mechanism and a high-speed image sensor

In this paper, we present a new fast rangefinding method based on a non-mechanical scanning mechanism and a high-speed image sensor. Although the light stripe rangefinding method often is utilized to measure three dimensional shape of an object, it is difficult to acquire dense range data at high-speed with conventional light stripe rangefinders. We proposed a fast rangefinding method based on two new ideas unlike conventional methods: (1) to move a parabolic light pattern onto the object by means of a non-mechanical mechanism; (2) to detect a true peak value using a high-speed image sensor. We have designed and built a prototype rangefinder. The rangefinder was able to acquire three-dimensional position at 500 ns which is faster than conventional rangefinders. As a result, the proposed method is effective for high-speed three-dimensional measurement.

Shape measurement of columnar objects with specular surfaces by slit ray projection method

In this paper, a method for measuring the shape of a columnar object with specular surfaces by a slit ray projection method is proposed. Although the slit ray projection method is effective for measuring the shape of an object having diffuse reflective characteristics, applying the method to an object with specular surfaces has hitherto been difficult. In this paper, a triangulation equation for a columnar object with specular surfaces is derived and used as the basis of a method for measuring the shape of an object having specular surfaces using applicable slit rays. The basic principle is that the angle of incidence of a slit ray reflected from the measured object into an image sensor is restricted specifically by the special design of the optical system. In addition to the theoretical study of the proposed principle, a system for measuring the shape of a columnar specular object and a diffuse object was created and its effectiveness was verified.

A novel position measurement with subpixel resolution using a charge-coupled device

This paper describes a novel subpixel measuring method using analogue data processing for a position-measurement system using a charge-coupled device (CCD). Since the position-measuring resolution of a system using a CCD is in principle limited to the pixel size, the output data from the CCD usually have been interpolated in some way for better resolution measurement. However, the ordinary digital method is difficult to apply to high-speed measurement because of the extra processing time required for analogue-digital conversion, memory storage and calculation. Our proposed analogue method realizes position measurement with subpixel resolution, leaving the analogue high-speed performance unchanged. The proposed method features realization of an interpolation algorithm exclusively with analogue circuitry, which calculates an actual peak position using the peak value and the values of the two pixels adjacent to the pixel that produced the peak value. We have designed and constructed the prototype circuitry for this system and experimental results demonstrated that the prototype circuitry has a resolution of the order of 1/10 pixel. We conclude that the method described in this paper is effective for real-time, in-line and low-cost position measurement with subpixel resolution for a measurement system using a CCD.