Abstract: A radially expandable multiple tubular member apparatus includes a first tubular member and a second tubular member engaged with the first tubular member forming a joint. A sleeve overlaps and couples the first and second tubular members at the joint.

Abstract: A method of obtaining improved feedforward data for a feedforward control system to move a component through a setpoint profile is presented. The setpoint profile includes a plurality of target states of the component each to be substantially attained at one of a corresponding sequence of target times. The method includes moving the component with the feedforward control system according to the setpoint profile using a first set of feedforward data; measuring a state of the component at a plurality of times during the movement; comparing the measured states with corresponding target states defined by the setpoint profile to obtain a set of errors; filtering the set of errors with a non-linear filter; generating improved feedforward data based on the filtered errors, the improved feedforward data being usable by the feedforward control system to move the component more accurately through the setpoint profile.

Abstract: In a method for controlling a positioning device, the positioning device has a stator and mover, the mover being movable relative to the stator; a position sensor configured to generate a position signal indicative of a position of the mover relative to the stator; a controller configured to receive the position signal, compare it to a setpoint signal to obtain an error signal, and generate a mover control signal on the basis of a signal component of the position signal, the controller having a variable gain. The positioning device, including the position sensor and the controller, defines a control loop. For error signals having a magnitude in a predefined range, the gain is selectively set to a value higher than a value for error signals having a magnitude outside the range.

Abstract: A system to move a component in accordance with a setpoint profile including a plurality of target states of the component, each of the plurality of target states to be substantially attained at one of a corresponding sequence of target times, is presented. The system includes a displacement device to move the component according to the setpoint profile; a storage device containing a library of feedforward data; a signal generating part configured to identify a plurality of time segments of the setpoint profile that correspond to entries in the library of feedforward data, and access the entries in order to construct a feedforward signal; and a feedforward control system to control the operation of the displacement device by reference to the feedforward signal constructed by the signal generating part.

Abstract: A method is described for controlling an optical disc drive apparatus (1) of a type comprising: scanning means (30) for scanning a record track of an optical disc (2), said scanning means (30) comprising at least one read/write element (34) to be positioned with respect to the disc (2), and at least one optical detector (35) for generating a read signal (SR); actuator means (50) for controlling the positioning of said at least one read/write element (34); a control circuit (290) for receiving said read signal (SR) and generating at least one actuator control signal (SCR) on the basis of at least one signal component of said read signal (SR), the control circuit (290) having at least one variable gain (?); said control circuit (290), said actuator means (50), said read/write element (34), and said optical detector (35) defining a control loop (200) having a critical frequency (?CP); the method comprises the steps of: selectively setting the gain (?), for signal components having a frequency in a predefined ran

Abstract: A method is described for detecting a mechanical shock in a disc drive apparatus (1) of a type comprising: scanning means (30) for scanning record tracks of a disc (2) and for generating a read signal (SR); actuator means (50) for controlling the positioning of at least one read/write element (34) of said scanning means; a control circuit (90) for receiving said read signal (SR), deriving at least one error signal (RE) from said read signal, and generating at least one actuator control signal (SCR) on the basis of said error signal. The method comprises the steps of: -determining a shock sensitivity function (SSHOCK) which describes the relationship between shocks (OExT) and said error signal; determining or at least approximating an inverse shock sensitivity function (S-lSHOCK) as the inverse of said shock sensitivity function (SSHOCK);—and applying said inverse shock sensitivity function (Sl-SHOCK)on said error signal.

Abstract: Control arrangement for and method of controlling a plurality of Lorenz motors (1, 2) actuating a payload (4) where the payload has a center of gravity (12). Height signals (z1, z2) are received from sensors sensing heights of said payload. At least one rotation angle of the center of gravity about a horizontal axis is calculated from these height signals (z1, z2) and from this at least one rotation angle control signals (C1, C2) for the Lorenz motors (1, 2) are calculated such that a predetermined rotational stiffness for supporting the payload (4) is achieved.

Abstract: A vibration isolation system isolates a body from its surroundings with respect to vibrations. The vibration isolation system includes active isolator devices that isolate and damp the body in unstable directions. However, such active isolators may exert damping forces not only in the unstable direction, but simultaneously in other stable directions due to mechanical coupling of the stable and unstable directions. As a result the damping and isolation in the other stable directions may be deteriorated due to the active isolation and damping. Employing modal decoupling, i.e. decomposing any vibration into independent directions, and isolating and damping in the independent directions, enables compensation of any vibration in an unstable direction without influencing the isolation and damping performance in any other, possibly stable, direction.