公开(公告)号：CA1109558A

公开(公告)日：1981-09-22

申请号：CA290791

申请日：1977-11-14

Applicant: IBM

Inventor： COMMANDER ROBERT D ,  GARDNER PETER A E ,  TAYLOR JOHN R

IPC: G05D3/12 ,  G11B5/596 ,  G11B21/10 ,  G11B5/012

Abstract: Data storage apparatus of the type employing a stack of rotatable storage disks accessible by a plurality of data heads ganged for movement over the data surfaces. The position of a data head during track following operations over a selected data surface being controlled by a hybrid servo signal consisting of low frequency components of position information signals derived from servo sectors around the data track being followed added to which are high frequency components of continuous position information signals derived either from a dedicated servo surface forming part of the stack or from an external position transducer. The continuous position information being provided by a servo transducer, which is also ganged to the data heads, in the form of two cyclic quadrature signals (90.degree. out of phase with each other) each having portions which are linear and co-extensive over the whole range of head displacement. The apparatus including servo control circuits for detecting during data track following position (caused for example by temperature variations or mechanical vibrations) beyond the linear region of the corresponding one of the two quadrature signals supplying the high frequency components and, upon such detection, switching to an adjacent linear portion of the other signal, or the inverse of the other signal, to either of which has been added an appropriate d.c. offset so that the linear portion of this other signal becomes an effective extension of the linear portion of the continuous servo signal corresponding to the data track being followed. By this means the a.c. gain of the servo circuits is maintained constant thereby improving the servo loop performance.

公开(公告)号：CA1061461A

公开(公告)日：1979-08-28

申请号：CA189831

申请日：1974-01-10

Applicant: IBM

Inventor： TAYLOR JOHN R

IPC: G05D13/62 ,  G11B5/55 ,  G11B21/08

Abstract: Track access mechanism for moving a transducer from track to track over a moving record surface is controlled in the following manner. The access mechanism is accelerated at the maximum rate attainable by the mechanism over a first number of tracks. Thereafter the transducer is driven at a constant velocity equal to the velocity attained as a result of the initial acceleration. Finally, a predetermined number of track from the destination track, the transducer is retarded to bring it to rest over the destination track.

公开(公告)号：FR2311374A1

公开(公告)日：1976-12-10

申请号：FR7610359

申请日：1976-04-01

Applicant: IBM

Inventor： COMMANDER ROBERT D ,  TAYLOR JOHN R

IPC: G11B5/55 ,  G05D3/12 ,  G11B5/596 ,  G11B21/08 ,  G11B21/10 ,  G11B5/02

Abstract: A positioning system for data storage apparatus in which a magnetic transducer is positioned relative to data tracks on a moving record member by means of a closed loop servo system. Improved velocity control information is provided to the servo system by pre-recorded servo tracks read by a single servo head forming part of the closed loop system. Each servo track consists of a plurality of servo cells, alternate ones of which are laterally displaced by half a track width. A position reference signal is prerecorded in each cell at a point which is predetermined to permit the signal to be sensed by the single servo head independently of any other detectable signal. Accordingly, a position error signal derived from displaced cells is always 90 DEG out of phase with the position error signal derived from undisplaced cells. During a track access operation, when the servo head is moved from one track to another track, the displaced and undisplaced cells are sensed by the single servo head to provide two separate position error signals. Control circuits combine selected portions of the two position error signals to provide a composite signal of improved linearity from which the velocity of the head during the access operation can be ascertained directly and employed to perform control functions dependent on velocity.

公开(公告)号：CA1126367A

公开(公告)日：1982-06-22

申请号：CA338286

申请日：1979-10-24

Applicant: IBM

Inventor： TAYLOR JOHN R ,  LAISHLEY WILLIAM J

IPC: G05D3/12 ,  G05B7/02 ,  G05B17/00 ,  G05B19/23 ,  G05B21/02 ,  G11B5/55 ,  G11B21/02

Abstract: A sampled data servo positioning system employs an actuator to move a member between a current and a target position. Incremental position feedback is provided only at sampling times. The system employs a model responsive to a velocity related input signal to produce a continually available model incremental position signal. Phase comparing means indicates phase differences between the model and sampled position signals at the sampling times. The system has two operational configurations in the first of which a source of saturation control signals is connected to the actuator to cause maximum acceleration or deceleration thereof. In this first configuration, the model is forced to track the actuator motion by means of feedforward plus feedback control. The feedforward signal represents actuator performance while the feedback signal is the position signal phase difference. In the second operational configuration, a velocity profile signal is applied to the model and the actuator is forced to track the model by means of feedforward plus feedback control. The feedback signal is again the position signal phase difference but the feedforward signal is a predetermined signal representing the desired actuator current to execute the velocity profile. The sampled data servo positioning system may be the access motion control system of a sector servo disk file. UK978021

公开(公告)号：CA1078512A

公开(公告)日：1980-05-27

申请号：CA252636

申请日：1976-05-14

Applicant: IBM

Inventor： COMMANDER ROBERT D ,  TAYLOR JOHN R

IPC: G05D3/12 ,  G11B5/55 ,  G11B5/596 ,  G11B21/08 ,  G11B21/10 ,  G11B5/82

Abstract: POSITIONING SYSTEM FOR DATA STORAGE APPARATUS Data storage apparatus comprises a movable record medium with at least one data record-and-playback head for recording data on and/or reading data from tracks on the medium. An actuator moves the data head or heads from track to track as required by external apparatus, the movement being controlled by reference to servo tracks pre-recorded on the medium and read by a servo head ganged for movement to the data head or heads. Each servo track consists of regions alternating between first and second states, transitions from a first to a second state and from a second to a first state being capable of producing different distinguishing signals in the servo head. Sections of the servo tracks are laterally displaced with respect to undisplaced sections by a distance less than one track width, the location of the displaced sections being selected such that the lateral displacement of servo tracks at the start and end of a section do not produce changes detectable by the servo head.