3D attitude measurement by means of spread spectrum modulated ultrasonic wave

Local position and attitude measurement methods are necessary for the navigation of autonomous robots and the other applications. In this paper, a 3D attitude measurement method is proposed. This method uses the spread spectrum modulated ultrasonic wave for the measurement of the pseudo-distance of each pathway between transmitter and receiver elements that are arranged in an array. The relative attitude between transmitter and receiver unit could be calculated from the relationship between these pseudo-distances. The use of spread spectrum modulation enables the high accuracy, noise tolerance, and coexistence of multiple transmitter devices by code division multiple access (CDMA) between transmitter and receiver elements. A pair of transmitter and receiver prototype for proposed method was manufactured, and the fundamental performance was examined in experiments. As a result, accuracy of σ=0.78 mm in the pseudo-distance measurement of each pathway between transmitter and receiver elements was confirmed, and about 0.01 rad resolution in the attitude measurement was also confirmed.

Extraction of yarn positional information from three-dimensional CT image of textile fabric using a yarn model for its structure analysis

This paper proposes a novel method for analyzing a textile fabric structure to extract positional information regarding each yarn using three-dimensional X-ray computed tomography(3D CT) image.Positional relationship among the yarns can be reconstructed using the extracted yarn positional information.In this paper,a sequence of points on the center line of each yarn of the sample is defined as the yarn positional information,since the sequence can be regarded as the representative position of the yarn.The sequence is extracted by tracing the yarn.The yarn is traced by estimating the yarn center and direction and correlating the yarn part of the 3D CT image with a 3D yarn model,which is moved along the estimated yarn direction.The trajectory of the center of the yarn model corresponds to the positional information of the yarn.The application of the proposed method is shown by experimentally applying the proposed method to a 3D CT image of a double-layered woven fabric.Furthermore,the experimental results for a plain knitted fabric show that this method can be applied to even knitted fabrics.

2-D localization system utilizing M-sequence encoded laser beam scanning

In this paper, as the active position measurement system, a novel method for a two-dimensional localization system using M-sequence signal is proposed. The feature of this system is to realize a position measurement only by scanning the encoded laser beams from fixing points to a measurement field, and by observing it. First, both the system configuration and encoding method were practically considered, and an order and an initial value of M-sequence signal were selected for encoding. This method is based on discrete angle measurement therefore the resolution has its own limitation. To overcome this limitation, analogue phase shift detecting method was introduced. System design was performed and applied to position measurement experiments. The experimental results show that the measurement error of the analogue method is 1/3 of that of the discrete method.

Fundamental study on short range measurement using RF time of flight based on Vernier effect

Recognizing the position of moving objects, facilities or important equipments has been regarded as a hot issue in the future environment which needs ubiquitous characteristics. Furthermore, it is indispensably needed to acquire location data in order to realize an infrastructure of sensor network system. Namely, distance data are the preliminary information to complete localization of a moving object in local area. Even though there have been several researches on this topic, there are however still much amount of problems in getting precisely exact distance data. Out of them, the research on using TOF (Time-of-flight) is very few as well as could be thought of as a cutting-edge technique. Moreover, it is very difficult to get minutely RF signal's TOF for getting short distance data; that is, very complicated signal processing skills are requested for realizing it. In this paper, we present a new methodology of RF short ranging technique based on vernier effect through using of heterogeneous operating clocks.

Acoustic CT system for temperature distribution measurement

In this paper, a measurement method for cross-sectional temperature distribution is addressed. A novel method based on an acoustic CT technique is proposed. Specifically, the temperature distributions are estimated using the time of flight data of several ultrasonic propagation paths. The times of the flight data contain both temperature and wind effect, and the method to select only temperature component is introduced. A filtered back projection method is applied to reconstruct the temperature distributions from the time of flight data. An experimental system was designed and fabricated to realize simultaneous temperature and wind velocity distribution measurements. Through this system, the effectiveness of the proposed measurement method is confirmed.