A Tuner that Accelerates Parameters

We propose a tuner, suitable for adaptive control and (in its discrete-time version) adaptive filtering applications, that sets the second derivative of the parameter estimates rather than the first derivative as is done in the overwhelming majority of the literature. Comparative stability and performance analyses are presented.Comment: 6 pages, 4 figure

On the Design of Direct Adaptive Controllers

Direct adaptive control systems without the familiar reference models is considered. A framework for design using quadratic cost functions is presented, and corresponding error equations are derived using ideas from linear-quadratic optimal control

Synchronization of Dynamic Networks for Knowledge Representation and Higher-Level Fusion

Abstract- This paper presents a novel approach to higher-level (2+) information fusion and knowledge representation using semantic networks composed of coupled spiking neuron nodes. Networks of spiking neurons have been shown to exhibit synchronization, in which sub-assemblies of nodes become phase locked to one another. This phase locking reflects the tendency of biological neural systems to produce synchronized neural assemblies, which have been hypothesized to be involved in feature binding. The approach in this paper embeds spiking neurons in a semantic network, in which a synchronized subassembly of nodes represents a hypothesis about a situation. Likewise, multiple synchronized assemblies that are out-of-phase with one another represent multiple hypotheses. The initial network is hand-coded, but additional semantic relationships can be established by associative learning mechanisms. Our approach will be demonstrated on a simulated scenario involving the tracking of suspected criminal vehicles between meeting places in an urban environment

On The Topologies Of Spaces Of Linear Dynamical Systems Commonly Employed As Models For Adaptive And Robust Control Design

Robustness and performance of a closed-loop adaptive system may profit from the use of switching logic, whether or not that is required for stability. This logic may take the form of a supervisory switching scheme responsible for choosing, at each instant of time, one among several candidate control signals to close the feedback loop. Perhaps the most promising way to make this choice is with basis on observations of suitably defined error signals, corresponding to each candidate control. While that in itself does not preclude the use of a compact subset of a finite dimensional linear space as parameter set, we believe that the use of parallel hardware and software may make it advantageous to take as parameter space a finite set. However it is not clear that with a finite parameter set it is possible to stabilize as large classes of admissible process models as in conventional adaptive control. This note uses elementary topological concepts to show how this can in principle be done, by..

A Tuner that Accelerates Parameters

We propose a tuner, suitable for adaptive control and (in its discrete-time version) adaptive filtering applications, that sets the second derivative of the parameter estimates rather than the first derivative as is done in the overwhelming majority of the literature. Comparative stability and performance analyses are presented

PicSat's Enduring Legacy. Probing the Flight of a Small Astronomical Satellite

International audienceObservation of planetary transits and other cutting-edge scientific missions can take advantage of affordable nanosatellites to probe interesting stellar targets. PicSat, a CubeSat dedicated to observing the Beta Pictoris star system, was designed to provide high-precision star pointing, a critical requirement for planetary transit detection. PicSat's Attitude Determination and Control System, responsible for delivering high-accuracy spacecraft pointing, requires dedicated development based on dynamic simulators. This paper presents a dynamic attitude and orbit propagation simulator for CubeSats in low Earth orbit, as well as for its de-tumbling mode. Validation has been performed through PicSat's in-flight data. High-precision dynamic models have been obtained for both attitude and orbit. Such models are well suited to the different mission phases, from spacecraft design to data exploitation. It is, therefore, a crucial tool to minimize the chance of failure of both the platform and the payload, especially in satellites such as PicSat, whose pointing depends on both. PicSat left an enduring legacy: its platform data allow us to obtain flight models that will be valuable for future missions