1,011,844 research outputs found
Open loop digital frequency multiplier
An open loop digital frequency multiplier is described which has a multiplied output synchronized to low frequency clock pulse. The system includes a multistage digital counter which provides a pulse output as a function of an integer divisor. The integer divisor and the timing or counting cycle of the counter are interrelated to the frequency of a clock input. The counting cycle is controlled by a one shot multivibrator which, in turn, is driven by a reference frequency input
Practical Open-Loop Optimistic Planning
We consider the problem of online planning in a Markov Decision Process when
given only access to a generative model, restricted to open-loop policies -
i.e. sequences of actions - and under budget constraint. In this setting, the
Open-Loop Optimistic Planning (OLOP) algorithm enjoys good theoretical
guarantees but is overly conservative in practice, as we show in numerical
experiments. We propose a modified version of the algorithm with tighter
upper-confidence bounds, KLOLOP, that leads to better practical performances
while retaining the sample complexity bound. Finally, we propose an efficient
implementation that significantly improves the time complexity of both
algorithms
Optimal Controller and Filter Realisations using Finite-precision, Floating- point Arithmetic.
The problem of reducing the fragility of digital controllers and filters
implemented using finite-precision, floating-point arithmetic is considered.
Floating-point arithmetic parameter uncertainty is multiplicative, unlike
parameter uncertainty resulting from fixed-point arithmetic. Based on first-
order eigenvalue sensitivity analysis, an upper bound on the eigenvalue
perturbations is derived. Consequently, open-loop and closed-loop eigenvalue
sensitivity measures are proposed. These measures are dependent upon the filter/
controller realization. Problems of obtaining the optimal realization with
respect to both the open-loop and the closed-loop eigenvalue sensitivity
measures are posed. The problem for the open-loop case is completely solved.
Solutions for the closed-loop case are obtained using non-linear programming.
The problems are illustrated with a numerical example
System identification from closed-loop data with known output feedback dynamics
This paper presents a procedure to identify the open loop systems when it is operating under closed loop conditions. First, closed loop excitation data are used to compute the system open loop and closed loop Markov parameters. The Markov parameters, which are the pulse response samples, are then used to compute a state space representation of the open loop system. Two closed loop configurations are considered in this paper. The closed loop system can have either a linear output feedback controller or a dynamic output feedback controller. Numerical examples are provided to illustrate the proposed closed loop identification method
USp(2k) Matrix Model: Schwinger-Dyson Equations and Closed-Open String Interactions
We derive the Schwinger-Dyson/loop equations for the USp(2k) matrix model
which close among the closed and open Wilson loop variables. These loop
equations exhibit a complete set of the joining and splitting interactions
required for the nonorientable Type I superstrings. The open loops realize the
SO(2n_f) Chan-Paton factor and their linearized loop equations derive the mixed
Dirichlet/Neumann boundary conditions.Comment: 22 pages, 13 figure
Characterisation of the influence function non-additivities for a 1024-actuator MEMS deformable mirror
In order to evaluate the potential of MEMS deformable mirrors for open-loop
applications, a complete calibration process was performed on a 1024-actuator
mirror. The mirror must be perfectly calibrated to obtain deterministic
membrane deflection. The actuator's stroke-voltage relationship and the effect
of the non- additivity of the influence functions are studied and finally
integrated in an open-loop control process. This experiment aimed at minimizing
the residual error obtained in open-loop control.Comment: 6 pages, 9 figures, Proceedings of the 1st AO for ELT conference,
June 2009, Pari
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