This paper presents a system which generates images of objects behind obstacles as if they are seen through the obstacles. For remote operation of robots such as disaster response robots, operational efficiency depends heavily on quality of visual information. Diminished reality, which has been proposed in the field of computer vision, is a technique which generates images in which as if users saw objects through obstacles. The proposed method uses a robot with an arm and two RGB-D sensors attached in front of and on the arm of the robot, acquires three-dimensional information of occluded areas and integrates the images to present see-through image, letting the sensor move along with the arm. In this method, past information of RGB-D images can easily be used to expand the field of view with low calculation cost, if the environment is static. The experiments with a manipulator robot show the ability to see through obstacles from arbitrary viewpoints in real time.
We have developed the deterministic figure correction process for fabricating the mandrel of a soft x-ray mirror. In this process, the figure correction is performed on the basis of the measured profile. We used roundness measuring machine equipped with a rotary air-bearing stage and laser displacement sensors. Repeatability higher than 1 nm was achieved by averaging the 10 measured profiles. We employed nozzle-type EEM (Elastic Emission Machining) to remove the surface material with a controllability of 1 nm. In the figure corrections, the dwelling time distribution of the EEM head is a parameter to adjust the removal profile. In this study, a rod lens was used as the test sample. The figure error of a profile in the circular direction could be improved. Finally, the circularity was achieved to be 10 nm in peak to valley.
A minimum-time driving algorithm is obtained about the moving on a curved path in space. The algorithm takes velocity, acceleration and jerk as constraints. By imposing a jerk constraint, the acceleration time-derivative is limited and smooth driving is guaranteed. It is concluded that the moving object's dynamics must be analyzed directly by using curvature and torsion of the path. It is also found that the given path must possess G2 or higher continuity for applying a jerk constraint. For a given set of velocity, acceleration and jerk constraints, it is proved that the minimum driving time depends on path length, curvature, torsion and curvature's path length derivative along the path. The resultant driving pattern guarantees minimum-time smooth driving.
A novel image quality inspection method that detects low contrast “mura” (non-uniform regions) has been developed by analyzing the Fourier spectrum of the images. The inspection images are transformed to Fourier frequency space, and the power spectrum is filtered using CSF(Contrast Sensitivity Function) to obtain the human eye sensitivity. The radial frequency and angular frequency histograms of the power spectrum are used to detect the image defects. A “mura” model experiments were executed to verify the novel method, and the experiments using 62 real samples showed good detection ability for the “mura” defect samples.
This paper describes the measurement method of piping using multiple laser slits. Measurement due to replacement or construction of new pipes is cumbersome work on the renewal of facilities in a chemical plant. Recently, three dimensional measurement systems with a laser scanner are widely used for piping measurements. However, the size of data obtained is very large since the data includes unnecessary information such as background data etc. Extra works are required to extract the appropriate information from the enormous data. In order to address this problem, we have developed a three-dimensional piping measurement system using multiple laser slits with random-dot projector. Using this system, just minimum data to specify a pipe, such as orientation and diameter of the pipe, are extracted effectively. Random dots are used to identify each slit. The arrangement state of multiple slits in the image are used to estimate the direction of the pipe. Once the direction of the pipe is determined, the data on each slits are arranged to be vertical along the centerline. The arranged data are used to estimate the cross-sectional shape. As the result, the pipe specifications are estimated effectively utilizing multiples laser slits.
FMCW (Frequency Modulated Continuous Wave) method has been used for long distance measurement. However, nonlinearity of optical frequency sweep of LD (Laser Diode) degrades the measurement accuracy. In this paper, first, the influence of nonlinearity of optical frequency sweep in distance measurement is defined by formulation. Second, the nonlinear sweep behavior is analyzed by using Hilbert transformation and the nonlinearity is reduced by making the LD current sweep nonlinear. The resultant performance of distance measurement is evaluated by comparing with a laser interferometer. The experimental result shows that it is possible to measure 1.8m distance with smaller than 10μm accuracy.
Silicon wafers for fabricating IC cards and smartphones must be less than a few tens of microns in thickness. After the wafer is thinned by backgrinding, the damaged layer is removed by chemical mechanical polishing (CMP) and dry polishing. A porous vacuum chuck is typically used to fix the wafer during machining. However, it is difficult to completely clean the porous chuck and to flatten a concave wafer with large warpage. To solve these problems, a water-film chuck is proposed. This chuck has a thin water film between the back surface of a wafer and the surface of the chuck. This paper describes the flattening characteristics of the water-film chuck. It was clarified that a quartz glass wafer 1.2 mm thick that has warpage of a few-hundred microns can be flattened to less than 10 μm over time. Then, a backgrinding silicon wafer with 1 mm warpage was flattened instantly below 20 μm by applying a fine water mist. In addition, the lateral restraint force per unit area was found to be over 10 kPa for a water-film thickness of less than 0.5 μm. Therefore, the water-film chuck can be used for not only wafer transfer but also grinding or light-load polishing.
The authors propose a new method of detecting the operations of a check ring by employing the torque load T in the reverse direction of rotation applied during injection at the servo motor for rotating the screw equipped to electric injection molding machines. Through experiments, the authors confirmed that the torque load T peak and ring closing timing match, and that there exists a clear negative correlation between the T time integral value Bf and molded product weight. In addition, check rings with different closing strokes S and external diameters D were used to investigate the correlations between the closing stroke/external diameter and Bf, and it was found that the larger S is, the greater is Bf, and that Bf increases suddenly as D decreases (interval with the cylinder increases). The torque load of the injection molding machine was monitored using the developed check ring operations detection method based on these results, and it was demonstrated that reverse flow amount can constantly be monitored with this method. These findings suggest that the developed method is useful for predicting the life of check rings.