US 4,792,870 AGranted

Method and apparatus for track accessing using a predicted state vector

AssigneeBull SAS

InventorDenis Pinson

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Abstract

A method and apparatus for displacing a system that is movable with respect to a carrier of data recorded on a plurality of tracks, including a reading head (TEL.sub.1), which is displaced on a given path the position on which is measured at predetermined sampling instants (kT), characterized in that: (1) at each instant kT, the value of the state vector X0 k/k-1 is predicted, as a function of the measured position x.sub.m (k-1) and of the control voltage u(k-1), which are considered at the preceding sampling instant (k-1)T; (2) the predicted state vector is compared with a reference state vector Wk); and (3) the control voltage u(k) is calculated as a function of a reference control voltage e(k) at the instant kT and of the difference .epsilon. (k) between the predicted state vector and the reference state vector.

Claims6

Dependent claims

A method for displacing a system (SYSMOB) that is movable with respect to a carrier (DISC) of data recorded on a plurality of tracks, the system being moved by an electric motor (ML) supplied with voltage/current by a supply generator (ALIM) controlled in turn by a control voltage u(k) and including at least one data reading/writing head TEL.sub.1 displaced on a given path from a departure track A to an arrival track B, the position x.sub.m (k) of the head (TEL.sub.1) on the path being measured at predetermined sampling instants kT by a position pickup (CAPPOS), comprising

(1) at each predetermined sampling instant kT, the value of the state vector XHD k/k-1 indicating the position and speed of the head (x, x) at that instant is predicted, as a function of the measured position x.sub.m (k-1) of the head and of the control voltage u(k-1), which are considered at the preceding sampling instant (k-1)T;
(2) the predicted state vector XHD k/k-1 is compared with a reference state vector Wk) indicating the reference position and speed which the head (TEL.sub.1) must have at the predetermined sampling instant kT;
and
(3) the control voltage u(k) is calculated as a function of a reference control voltage e(k) of the motor at the predetermined sampling instant kT and of the difference .epsilon.(k) between the predicted state vector XHD k/k-1 and the reference state vector Wk).

1 more element

An apparatus for displacing a system that is movable with respect to a carrier of data recorded on a plurality of tracks, the system being moved by an electric motor (ML) supplied with voltage/current by a supply generator (ALIM) controlled in turn by a control voltage u(k) and including at least one data reading/writing head TEL.sub.1 displaced on a given path from a departure track A to an arrival track B, the position x.sub.m (k) of the head (TEL.sub.1) on the path being measured at predetermined sampling instants (kT) by a position pickup (CAPPOS) comprising:

(a) state observation means (OBSET) for predicting the value of the state vector XHD k/k-1 at each predetermined sampling instant kT, which receives both the value of the head position x.sub.m (k-1) measured by the position pickup (CAPPOS) at the preceding sampling instant (k-1)T and the value of the control voltage u(k-1) at this same preceding sampling instant;
(b) means for memorizing a reference control voltage e(k) and a reference state vector Wk) for each sampling instant kT;
(c) means (COMP) for comparing the predicted state vector XHD k/k-1 with the reference state vector W(k) and for calculating the difference .epsilon.(k) between them;
and
(d) regulating means (MREG) calculating the control voltage u(k) as a function of the reference control voltage e(k) and of the difference .epsilon.(k) between the predicted state vector and the reference state vector.

2 more elements

Dependencies are inferred from the claim text.