The tracking (mean-square timing-error) performance of a linearized datatransition tracking loop (LDTTL) is presented. The difference between the LDTTL and the conventional DTTL is that the hard-limiter nonlinearity in the conventional DTTL’s inphase arm is replaced by a linear device, as suggested by the maximum a posteriori (MAP) open-loop estimate of symbol timing at low symbol signal-to-noi...

This paper describes a dynamic controller for rotorcraft landing and hovering in ground effect using feedback control based on flowfield estimation. The rotor downwash in ground effect is represented using a ring-source potential flow model selected for real-time use. Experimental verification of the flow model is also presented. A nonlinear dynamic model of the rotorcraft in ground effect is p...

In this work the authors introduce a notion of zero dynamics for distributed parameter systems governed by linear parabolic equations on bounded domains with controls implemented through first order linear boundary conditions. This notion is motivated by classical root-locus constructs from finite dimensional linear systems theory. In particular, for scalar proportional output feedback this not...

Abstract This paper exploits the equivalence between constrained dynamics problems and a class of tracking control problems. An alternative derivation of the modern formulation of Parczewski and Blajer (1989) is presented, including some new analysis on the “almost singular” case, followed by a critique of the classical Lagrangian formulation. In addition, a new formulation which allows the con...

In this paper, a new method to manage the stabilization and control problems of n-dimensional linear systems plus dead time, which includes one, two, or three unstable poles, is proposed. The methodology proposed in work an Observer-based Proportional-Integral-Derivative (PID) strategy, where observer PID controller are used relocate original open-loop poles stabilize resultant closed-loop syst...

The charge couple device (CCD) tracking loop of a fast steering mirror (FSM) is usually used to stabilize line of sight (LOS). High closed-loop bandwidth facilitates good performance. However, low-rate sample and time delay of the CCD greatly limit the high control bandwidth. This paper proposes an error-based observer (EBO) to improve the low-frequency performance of the CCD tracking system. T...

PURPOSE To investigate the relationship between photopic open-loop accommodation and vergence and the effect of mental effort on these positions. METHODS Twenty subjects (11 men and 9 women) viewed monocularly a photopic (25 cdm-2), high-contrast (90%) Maltese cross-target for 3 minutes, through a 0.5-mm pinhole drilled into an infrared filter. Accommodation was measured objectively at 1-seco...

Because of the cost and complexity associated with sensory feedback, open-loop control of ionic polymer–metal composite (IPMC) actuators is of interest in many biomedical and robotic applications. However, the performance of an open-loop controller is sensitive to the change in IPMC dynamics, which is influenced heavily by ambient environmental conditions including the temperature. In this pape...

This paper presents the results of an experiment in which a cybernetic approach has been used to investigate the effect of motion filter setting changes and display type on simulator fidelity. Pilot control behavior, pilot remnant, open loop behavior, open loop performance and subjective evaluations in a real jet-aircraft were compared with that in a high-fidelity motion base simulator. The tas...

In order to implement a quasi-optimal trajectory derived from pinch theory [1,2], a temperature tracking control system composed by an open-loop reflux ratio control plus a closed-loop correction for disturbance rejection is proposed. To adjust the closed-loop controller we use the referential dynamic reaction of the process [3] and tuning rules [4] that, though they were originally developed f...