http://ieeexplore.ieee.org TOC Alert for Publication# 87 2012 February 10 20 2 C1 C4 157 20 2 C2 C2 39 20 2 289 290 324 20 2 291 291 82 20 2 292 295 689 20 2 296 322 2815 20 2 323 334 2044 20 2 335 345 2586 20 2 346 355 2337 20 2 356 368 3585 $H_{infty}$ approach, takes into account the measured plant transfer function, the disturbance characteristics of the tape path, and the properties of servo channel. These elements are combined to investigate the track-following performance achievable with a new high-SNR magnetic tape based on perpendicularly-oriented BaFe particles. With this setup, a record closed-loop track-following performance of less than 14 nm PES standard deviation is demonstrated.]]> 20 2 369 381 2741 ${cal H}_{infty}$ filtering are employed to perform sensor fusion, and the resulting state estimates in turn serve to design feedback controllers. An alternate approach is to design a multiple-input single-output controller using either the ${cal H}_{2}$ or ${cal H}_{infty}$ control paradigm. These controllers are investigated in detail to reveal the underlying structure and the inherent sensor fusion that takes place. Comparisons are made between the two approaches.]]> 20 2 382 394 3266 20 2 395 401 1399 $H_{infty}$ controller for HDD servos with ISRs via discrete Riccati equations is first obtained. The resulting controller is subsequently demonstrated to be periodically time-varying and implementable. Simulation and experimental studies, which have been carried out on a set of hard disk drives, demonstrate that the proposed control synthesis technique is able to handle ISRs and can be used to conveniently design a loop-shaping track-following servo that achieves the robust performance of a desired error rejection function for disturbance attenuation. Experimental results on ten actual 2.5" hard disk drives show around 27% improvement of the $3sigma$ PES was obtained by the proposed control algorithm.]]> 20 2 402 407 1172 20 2 408 415 1991 20 2 416 423 1912 20 2 424 437 1138 20 2 438 452 966 20 2 453 464 1582 20 2 465 472 742 20 2 473 479 361 20 2 480 485 279 20 2 486 494 655 20 2 495 503 750 20 2 504 512 728 20 2 513 519 708 20 2 520 529 945 20 2 530 537 549 20 2 538 545 1413 20 2 546 553 558 ${rm H}_{infty}$ feedforward compensators for active vibration control systems subject to wide band disturbances. The procedure takes in account the inherent “positive” feedback coupling between the compensator system and the measurement of the image of the disturbance. It also takes advantage of the availability of reliable models obtained by system identification. A controller order reduction technique is proposed for reducing the complexity of the nominal ${rm H}_{infty}$ controller without degrading the performance. Experimental results obtained on an active vibration control system for a flexible mechanical structure will illustrate the procedure.]]> 20 2 554 561 1513 claims that: 1) its sliding mode control does not contain any discontinuous function (or switching function) and 2) hence is chatter-free. In this letter, we present a simple counter-example to claim 1).]]> 20 2 562 562 56 20 2 563 563 43 20 2 564 564 320 20 2 C3 C3 40