Hitachi, Ltd.

Kenji Toki

Fujio Tajima

Hideki Tanaka

Tomokazu Ishii

Kooetsu Okuyama

Toshihiro Arisaka

Kazuo Sakai

Yasuhiro Nemoto

Munetake Kanna

Kouetsu Okuyama

Hirofumi Kanai

There is provided a magnetic tape device capable of highly accurate positioning at a high speed. For this purpose, the head is driven in the direction of the width of the tape by eliminating the friction between the tape the head. In order to allow positioning in the direction of the width of the tape, even if a servo signal cannot be read from a servo track, the absolute position of the head from a reference position is detected, and the head is controlled based on the absolute position.

Magnetic tape device and method of controlling magnetic tape device

A library apparatus has a recording and reproducing unit and a storing rack having a number of shelves each adapted to store a recording medium and a carry robot is moved between shelves of the storing rack or between the recording and reproducing unit and a shelf of the storing rack to load/unload a target recording medium to/from a shelf or the recording and reproducing unit. A photosensor is mounted to the tip of a hand of the carry robot. The carry robot is moved to the target shelf in two-step control. Namely, a robot controller calculates the position of the target shelf and moves the robot to the calculated position in a coarse control. Then, a position of a framework relating to the target shelf of the storing rack is detected accurately based on the signal from the photosensor and a position recognition controller determines a displacement of an actual position of the target shelf from the calculated position to apply positional correction to the target position and causes the robot controller to position the robot hand to the actual position in a fine control. Resulting position correction information is stored in a storing rack position information memory to decrease the operation time in the second and ensuing positioning operations.

Library apparatus that corrects relative position displacement between a

A servo-mechanism control system calculates an operation value to be applied to a control object from a desired value of a control output and a detected control output of the control object, and drives the control object based on the calculated operation value so that the control output becomes equal to the desired value. The control system is less sensitive to the variation of characteristics of the control object and disturbances, and stable control is accomplished by a simple circuit arrangement. A mathematical model and its inverse function, which are based on the assumption that the control system is not subjected to the variation of characteristics of the control object and disturbances, are used to calculate a model-based control output. In error of the operation value is calculated from the difference between the model-based control output and the detected control output by using the inverse function of the mathematical model, and the operation value applied to the control object is modified by subtracting the error from the calculated operation value. Alternatively, the model-based operation value is calculated from the detected control output by using only the inverse function of the mathematical model, and the operation value is modified based on the difference between the model-based operation value and the calculated operation value.

Control method and apparatus for a servo- mechanism

In a servo system using a discrete signal relative to a position, a time delay and an error upon detecting a speed due to lack of positional information are eliminated to achieve a positioning to a target position in a short time. A pulse signal X.sub.P relative to a position is used to establish synchronization with an observer which is adjusted to match with an actual apparatus comprising a load, a motor and so on, and an estimated speed value or an estimated position value generated by the observer are used to determine an operating signal for the servo system.

Servo control method for a servo system

A servo-mechanism control system calculates an operation value to be applied to a control object from a desired value of a control output and a detected control output of the control object, and drives the control object based on the calculated operation value so that the control output becomes equal to the desired value. The control system is less sensitive to the variation of characteristics of the control object and disturbances, and stable control is accomplished by a simple circuit arrangement. A mathematical model and its inverse function, which are based on the assumption that the control system is not subjected to the variation of characteristics of the control object and disturbances, are used to calculate a model-based control output. An error of the operation value is calculated from the difference between the model-based control output and the detected control output by using the inverse function of the mathematical model, and the operation value applied to the control object is modified by subtracting the error from the calculated operation value. Alternatively, the model-based operation value is calculated from the detected control output by using only the inverse function of the mathematical model, and the operation value is modified based on the difference between the model-based operation value and the calculated operation value.

Control method and apparatus for a servo-mechanism

A magnetic head is provided in a tape transport path along which a magnetic tape is transported from one reel directly to another reel. In order to record or reproduce data to or from the magnetic tape with the magnetic head while the magnetic tape travels, it is necessary to stabilize a tape velocity at the magnetic head position to a desired velocity. The tape velocity at the magnetic head position is determined based on tape velocities at the respective reel positions, a tape path length from the head to one reel and a tape path length from the head to the other reel, and a closed loop control is effected by using the tape velocity at the magnetic head position to match the tape velocity to a desired velocity.

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Odawara, Japan

Kenji Toki