Improvements of performance of a vibration isolation table supported by an air-spring are attempted. A servo-control mechanism regulates the air in the air-spring so that the table can always remain immobile in spite of the vibrations of the floor. The principle of this servo-control is as follows. At the instant of upward movement of the table, the air in the air-spring is impelled to flow out. At the instant of downward movement of the table, the air is pushed to flow in. In this paper, a method of determining an optimal control-signal, which regulates the air in the air-spring, is discussed from a learning control standpoint by a microcomputer. For periodic disturbances, adjustment of control signal for both amplitude and phase is applied. For random disturbances, adjustment of control gain only is applicable.
A motion diagram showing the relative motion of various machine parts is necessary in order to fully understand, whether the machine properly fulfills its functions. However, in the case of a sewing machine, conventional motion diagrams for both the machine and sewing thread are usually used. This suggests that only a part of the sewing thread motions is given in connection with the machine motion.In this paper, new sewing thread motion diagrams involving various sewing factors such as fabric thickness, stitch length, and thread elongation are proposed for a lockstitch sewing machine. By using the new motion diagrams, it is shown that the relation between needle thread movement and tension changes during one cycle of sewing. It is also shown how the various sewing factors affect the tightening of stitches in the process of stitch formation.
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