Although planetary gear trains are presently widely used in hybrid vehicles as a power distribution system and in electric vehicles as a high reduct ion system, its noise and vibration problem has emerged. There are many reports dealing with two-axis driving characteristic of planet gear. However, there have been few reports dealing with three-axis driving one of it. In the present report, we construct a three-axis driving equipment to measure three-axis rotation speed and to estimate dynamic characteristic of planetary gear t rain, based on sun gear speed contour map in continuously variable transmission of it. Moreover, we also consider motion of planet gear as a kind of link mechanism model and focus on an instantaneous center of rotation planetary such as link motion. As a result, it is clear that an unstable meshing occurs when rotation direction of the sun gear reversed under the three-axis transition. Accordingly, the driving condition where the carrier is much slower than the ring gear should be severe because instant center moving distance is longest among every driving condition and sun gear rotation direction is reversed in continuously variable transmission under three-axis driving.
This paper proposes an eccentricity computation algorithm using the complete elliptic integral of the second kind for a pre-aligner. A CD-SEM is an inspection tool of the semiconductor device using the electron beam. Highly precision CD-SEM is required by the high integration of the semiconductor device progressing. Also, high throughput CD-SEM is required by the increased production of semiconductor devices which are smaller and thinner, because they are required by growing of smartphones and tablet PCs. A pre-aligner which is installed to improve throughput is a part of CD-SEM. The pre-aligner computes eccentricity of a Si wafer, and transfers it to inside the CD-SEM precisely. It is a non-contact type which can prevent contamination using a line image sensor to compute eccentricity. However, it is difficult for a conventional method to be highly precise, because it depends on an approximation and an experience even though it computes eccentricity using derivative and statistics calculation. At first, this paper shows that a wave pattern of the line image sensor is proportional to the complete eccentric integral of the second kind based on geometry analysis. Then, it proposes highly precise eccentricity calculation algorithm based on an analytical result. Finally it shows high precision pre-aligner by an experimental result.
The ellipsoidal mirror for X-ray nano-focusing is a key devise in X-ray analytical methods. The ellipsoidal mirror is fabricated by replicating a mandrel. The surface accuracy of the mandrel should be extremely high to obtain the high-quality replicated products. The accuracy is mainly determined by the metrology used in the fabrication process. In this study, we developed a surface profiler using multiple displacement sensors and reference mirrors, in which one sensor is used for measuring the mandrel surface and the others are used for in-situ monitoring motion errors of scanning stages. The spatial resolution and the repeatability was confirmed to be 0.05 mm and 0.14 nm (σ), respectively. The system error originated from the figure errors of the references is calibrated using flat mirror with peak-to-valley of 1nm level. Then, the positioning error of the scanning stage was compensated using a tilted flat mirror. The measured profiles were well coincided with 0.41 nm (σ) reproducibility even when the mandrel position was shifted on the profiler. Finally, by combining the developed profiler and EEM (Elastic Emission Machining) system, the figure accuracy of 1.8 nm in RMS was achieved on the longitudinal profile of the mandrel, which will be actually used for fabricating X-ray mirrors.
This paper proposes a method of vibration control of a flexible arm by input shaping based on wave model. Through the wave model which is one of the distributed parameter system, we can consider the infinite numbers of resonance in the flexible arm. Using the inverse system of the flexible arm, we design the input shaper for vibration suppression. Based on the frequency analysis, we show the characteristics of the proposed input shaper based on wave model. Using a single link flexible manipulator, the proposed method is compared with the conventional methods considering the finite numbers of the resonance frequency. From the experimental results, the effectiveness of the proposed method has been confirmed in terms of Root Mean Squared Error (RMSE) and the settling time.
In recent years, various kinds of small flying or hovering robots have been developed at various research institutions. The robots are expected to be used for observing the places where humans cannot enter, and any security cameras are not placed. However, it is difficult to keep robots hovering in the air for a long time because power loads of motors are heavy and battery capacities are limited. For this reason, a hovering robot stickable to a wall over 24 hours without supplying powers to main rotors was investigated here. By developing a new sucker with a soft surface ring of thermoplastic styrene elastomer and new mechanisms for dealing with pitching and yawing, a robot surely stickable to a wall was successfully fabricated.
This paper describes characteristic analyses for a two-dimensional friction model. The model is an extension of a conventional friction model for one-dimensional motion: the Dahl model. The extended model is derived by replacing scalar variables in the original Dahl model with vectors. The analyses are made in typical planar two-dimensional motion. The force-displacement hysteresis loop of the two-dimensional model is represented as second order differential equations in circular arcurate motion, while that of the original model is represented as first order one. The proposed model produces centripetal force when the radius of the circular motion is rather small, and friction force when the radius grows. That corresponds to the displacement-dependent stiffness of the original model. The proposed two-dimensional model preserves those principal properties of the original one-dimensional model.
In this study, a method to facilitate the check ring closing motion by reversing or advancing the screw after the metering process was proposed for the purpose of stabilizing the injection amount of resin. Experiments were conducted on the proposed method, and it was confirmed that rotating the screw in the reverse direction resulted in good closing efficiency in the plastication of PBT, but the check ring did not completely close even when the screw was rotated in the reverse direction in the plastication of low viscosity PC. On the other hand, advancing the screw in the normal direction was found to be effective for improving the check ring closing motion and suppressing backflow in the plastication of PBT and PC. It was also confirmed that these effects are further increased when screw advancement and rotation are both performed. Furthermore, it was indicated that backflow estimation by detecting screw rotating motor load was a useful tool for optimally setting the screw reverse rotation angle when reversing screw rotation and the compression pressure when advancing the screw. Variation of the weight of the molded part was evaluated, and it was confirmed that the stability of resin injection improved remarkably with this stabilization method compared to the standard injection method without screw reverse rotation or advancement.