International Business Machines Corporation

Other

Kevin Jack Erickson

Zine-Eddine Boutaghou

Richard Greenberg

Hal Hjalmar Ottesen

Earl Albert Cunningham

Dana H Brown

Gregory Alan Chaney

John Charles Brock

Timothy J Blank

Mark David Hagen

Patrick Joseph McCarthy

John Charles Purkett

John Jeffrey Stephenson

Richard Karl Kirkman

Thomas W Glaser

Peter M Herman

Scott Alan Plaetzer

Daniel L Good

Richard H Estry

Dean C Palmer

Douglas W Nelson

Alexei H Sacks

An anti-collision system for use by a mobility scooter to reduce collisions between the mobility scooter and objects or ledges is disclosed. The system comprising an input/output communication interface and an anti-collision circuitry configured to: receive a movement signal from the mobility scooter, the movement signal signaling a movement variable and a direction, receive proximity data from one or more proximity sensors through the input/output communication interface, perform a determination as to whether the received proximity data indicates the mobility scooter is within a proximity threshold, wherein the proximity threshold corresponds to the movement variable, and in response to determining the received proximity data indicates the mobility scooter is within the proximity threshold, provide one or more control signals to a controller, the controller in communication with at least a motor or a brake of the mobility scooter.

Anti-collision system for personal mobility scooters

A computer system and storage medium that, in an embodiment, prohibit breakpoints from being set within a protected range. In an embodiment, a protected range may be an atomic operation synchronization code range, either based on instructions generated by a compiler or based on source statements that are compiler directives. When a command, such as an add breakpoint command is received, the address of the breakpoint is compared to the protected range, and if the address is within the protected range, the breakpoint is not set. In another embodiment, if the address is within the protected range, the breakpoint is set before the start or after the end of the protected range. In this way, the problems of endless loops may be obviated.

Protecting code from breakpoints

A method, apparatus, system, and signal-bearing medium that, in an embodiment, prohibit breakpoints from being set within a protected range. In an embodiment, a protected range may be an atomic operation synchronization code range, either based on instructions generated by a compiler or based on source statements that are compiler directives. When a command, such as an add breakpoint command is received, the address of the breakpoint is compared to the protected range, and if the address is within the protected range, the breakpoint is not set. In another embodiment, if the address is within the protected range, the breakpoint is set before the start or after the end of the protected range. In this way, the problems of endless loops may be obviated.

Protecting a code range in a program from breakpoints

A method, apparatus, system, and signal-bearing medium that in an embodiment determine whether an instruction at which an address watch breakpoint occurs is within a hardware synchronization mechanism range in a program. If the determination is true, a special breakpoint is set following the hardware synchronization mechanism range, the address watch breakpoint is temporarily disabled, and the machine state is saved. When the program encounters the special breakpoint following the end of the hardware synchronization mechanism range, the saved machine state is presented. In this way, endless looping in programs protected by hardware synchronization mechanisms may be prevented.

Address watch breakpoints in a hardware synchronization range

A method, apparatus, system, and signal-bearing medium that in an embodiment map a pointer to a target indirectly via a pointer map. In an embodiment, the pointer map is stored in a reserved area and an entry for the pointer in the pointer map includes a back-pointer containing an address of the pointer and a target-address containing the address of the target. When the pointer is accessed, the pointer is checked to ensure its contents point at the entry in the pointer map in the reserved area and that the back-pointer in the pointer map entry points back at the pointer. In this way, pointers are protected from being modified illegitimately.

Secure pointers

An electric motor, which is preferably a disk drive spindle motor, contains a multi-phase stator driven by switching the phases of drive current at corresponding commutation angles of the rotor. Small semi-random offsets are introduced into the commutation angles at which the drive current is switched, spreading the frequency of excitation over a wider range, and reducing the peak harmonic excitation at the switching frequency. Preferably, a table of offsets is maintained, and an offset from the table is added to each commutation point. The table preferably has more entries than the number of commutation points, the entries being cycled on a round-robin or other basis.

Reduced noise electric motor for disk drive data storage devices

A capacitor discharge retract system is provided for small disk drives wherein the small spindle size is incapable of generating enough electrical energy to enable conventional actuator retraction and the form factor is too small to accommodate capacitors of sufficient size to enable a conventional capacitive discharge system. A capacitive discharge retract technique is enabled using an elevated voltage, significantly above the disk drive supply voltage, to allow smaller capacitive storage elements to perform the function. The effectiveness of the system is further enhanced in those environments where a source of the required elevated voltage can be found already resident in the device circuitry where it was generated to support another function.

Actuator retract/unload system for low power disk drives

Rotary actuator arc compensation correction method and apparatus are provided for a direct access storage device (DASD). A reference feedforward correction signal is generated at each of a plurality of sectors around a predetermined track on a disk surface. A specific selected track is identified, and both magnitude and phase of the generated reference feedforward correction signal are modified to correct for the arced trajectory caused by the rotary actuator at the specific selected track. Improved actuator servo control is provided by using pseudo sector compensation to interpolate the feedforward correction signal between servo sectors.

Method and apparatus for rotary actuator arc compensation correction in

A demodulator system for identifying the position of a transducer assembly over a disk of a direct access memory device. The demodulator identifies alias cases and uses information placed in the boundary between tracks to generates a more robust indication of the location of the transducer assembly.

Disk and storage device having an anti-alias data pattern located on a

An apparatus and method for correcting for track misregistration when a slider or head assembly contains a separate read element and write element. The offset is determined at a first position and at a second position of the actuator arm assembly. From these offsets a constant and a multiplier are determined for determining an offset as a function of the cylinder location. Also disclosed is a method and apparatus for minimizing distance traveled to prevent misregistration when repositioning between the read element and a write element. The read element is intentionally offset from the write element at an angle so as to minimize the distance traveled across the disk.

Method and apparatus for positioning transducers to correct for read and

A reduced size brushless DC motor preferably for use as a disk drive spindle motor includes a rotor having two sets of permanent magnets, and a stator having separate portions corresponding to the two sets. An upper set of permanent magnets and the corresponding portion of the stator are located within the upper portion of the hub, which fits within the holes of the disks of a disk drive. A lower set of permanent magnets and corresponding portion of stator are located in the flange of the motor hub which supports the disks from below. In one embodiment, the stator core has an L-shaped cross-sectional area in the plane of the motor axis, one leg of the L driving the upper set of magnets in the rotor and the other leg driving the flange magnets. In a second embodiment, the stator core includes two separate pieces, one corresponding to each set of permanent magnets. In either embodiment, the separate coils or coil portions may be electrically connected in series or in parallel, or may be connected to switches enabling them to be driven in series or parallel selectively. Furthermore, the phases of the two sets of permanent magnets may be staggered to reduce the effects of transition from one magnetic pole to the next. Where the stator core includes two separate pieces, it is also possible to stagger the stator phases as well, reducing torque pulsations and wire interference.

Disk drive spindle motor having split windings for each phase

A digital storage system is disclosed in which a flying read/write head is loaded onto the surface of moving storage media with controlled velocity to avoid contact with the surface of the storage media. Head load velocity is detected by measuring the back EMF generated by the head arm actuator. Improved control and accuracy is obtained by breaking up the head arm actuator drive power into a series of pulses and measuring the back EMF induced into the low impedance voice coil of the head arm actuator in between pulses but only after the actuator current has been reduced to substantially zero in order to avoid interference by actuator current induced voltages.

Pulsed current velocity controlled head load method and apparatus which

A reduced size brushless DC motor preferably for use as a disk drive spindle motor includes a rotor having two sets of permanent magnets, and a stator having separate portions corresponding to the two sets. An upper set of permanent magnets and the corresponding portion of the stator are located within the upper portion of the hub, which fits within the holes of the disks of a disk drive. A lower set of permanent magnets and corresponding portion of stator are located in the flange of the motor hub which supports the disks from below. In one embodiment, the stator core has all L-shaped cross-sectional area in the plane of the motor axis, one leg of the L driving the upper set of magnets in the rotor and the other leg driving the flange magnets. In a second embodiment, the stator core includes two separate pieces, one corresponding to each set of permanent magnets. In either embodiment, the separate coils or coil portions may be electrically connected in series or in parallel, or may be connected to switches enabling them to be driven in series or parallel selectively. Furthermore, the phases of the two sets of permanent magnets may be staggered to reduce the effects of transition from one magnetic pole to the next. Where the stator core includes two separate pieces, it is also possible to stagger the stator phases as well, reducing torque pulsations and wire interference.

A phase plane trajectory trough method and apparatus for fast settling of a data transducer for positioning a transducer head over a selected track on a disk surface are provided for use in a disk file. The disk file includes at least one disk mounted for rotation about an axis and the disk has at least one disk surface including a plurality of data tracks for storing data. An actuator moves the transducer head from one track location to another track location. A controller is coupled to the actuator for applying a gain control signal to control movement of the actuator. A phase plane trajectory trough function is defined for the disk file. Velocity and position states of the actuator are estimated and compared with the phase plane trajectory trough function for generating a base correction factor. The controller is responsive to both the estimated velocity and position states and the phase plane trajectory trough (PPTT) function for modifying the gain control signal.

Growing community of inventors

Rochester, MN, United States of America

Kevin Jack Erickson