Behrooz Shahsavari

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This paper examines the limits of performance in systems with periodic irregular sampling rate when the actuation is not necessarily synchronized with the sampling. For such a system, three sampling and actuation schemes are considered: when the sampling and control rate are both regular, when they are both irregular, and when the sampling rate is irregular(More)
This paper presents an adaptive repetitive controller for active tracking (rejecting) of unknown periodic trajectories (disturbances). The proposed control law is based on a modified filtered-x least mean squares (MFX-LMS) algorithm with a novel variable step size that improves the convergence rate and fades the steady state excess error in a stochastic(More)
This paper presents an online adaptive controller to compensate damping and stiffness frequency mismatches in vibratory gyroscopes. This adaptive controller is running together with the method of averaging. The adaptive controller first estimates the effective damping and stiffness frequency mismatches using least square method and then compensates these(More)
In this paper we develop a modified filtered-x least mean squares (MFX-LMS) method to synthesis an adaptive repetitive controller for rejecting periodic disturbances at selective frequencies. We show how a MFX-LMS algorithm can be utilized when the reference signal is deterministic and periodic. A new adaptive step size is proposed with the motivation to(More)
This paper considers robust controller design for track-following in hard disk drives (HDD) with irregular sampling of the position error signal (PES) but regular (clock-driven) control updates. This sampling and actuation behavior is modeled by applying a novel discretization method to a continuous-time model of an HDD, resulting in a discrete-time linear(More)
Aircraft Electric Power Systems (EPS) route power from generators to vital avionics loads by configuring a set of electronic control switches denoted as contactors. The external loads applied to an EPS, power requirement of the system, electrical component failure events, and the dynamics of the system are inherently uncertain. In this paper, we address the(More)
An adaptive feedforward controller design for tracking repeatable runout (RRO) in bit patterned media recording (BMPR) is proposed for single stage hard disk drives (HDD). The technique is based on modified filtered-x least mean squares (MFXLMS) algorithm with deterministic periodic input, and a novel variable step size that boosts both the convergence rate(More)
This paper proposes a novel direct adaptive control method for rejecting unknown deterministic disturbances and tracking unknown trajectories in systems with uncertain dynamics when the disturbances or trajectories are the summation of multiple sinusoids with known frequencies, such as periodic profiles or disturbances. The proposed algorithm does not(More)
In non-uniform sampled systems, the measurements are arriving at irregular time intervals. However, the control is updated at regular time intervals. An observer is required to obtain the estimate of the states during the control update times. We evaluate two observer designs: A Kalman filter and a gain-scheduling observer. The Kalman filter has the optimal(More)