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Toulouse, France

Lanusse P.,French National Center for Scientific Research | Oustaloup A.,French National Center for Scientific Research | Pommier-Budinger V.,ISAE
International Journal of Bifurcation and Chaos | Year: 2012

Fractional complex order integrator has been used since 1991 for the design of robust control-systems. In the CRONE control methodology, it permits the parameterization of open loop transfer function which is optimized in a robustness context. Sets of fractional order integrators that lead to a given damping factor have also been used to build iso-damping contours on the Nichols plane. These iso-damping contours can also be used to optimize the third CRONE generation open loop transfer function. However, these contours have been built using nonband-limited integrators, even if such integrators reveal to lead to unstable closed loop systems. One objective of this paper is to show how the band-limitation modifies the left half-plane dominant poles of the closed loop system and removes the right half-plane ones. Also presented are how to obtain a fractional order open loop transfer function with a high phase slope and a useful frequency response, and how the damping contours can be used to design robust controllers, not only CRONE controllers but also PD and QFT controllers. © 2012 World Scientific Publishing Company. Source

Alazard D.,ISAE
WCE 2010 - World Congress on Engineering 2010 | Year: 2010

This paper presents a general kinematic analysis method for complex gear mechanisms. This approach involves the null-space of the adjacency matrix associated with the graph of the mechanism weighted by complex coefficients. It allows to compute the rotational speed ratios of all the links and the frequency of all the contacts in this mechanism (including roll bearings). This approach is applied to various examples including a two degrees of freedom car differential. Source

Pizziol S.,ONERA | Tessier C.,ONERA | Dehais F.,ISAE
Ergonomics | Year: 2014

Analyses of aviation safety reports reveal that human-machine conflicts induced by poor automation design are remarkable precursors of accidents. A review of different crew-automation conflicting scenarios shows that they have a common denominator: the autopilot behaviour interferes with the pilot's goal regarding the flight guidance via 'hidden' mode transitions. Considering both the human operator and the machine (i.e. the autopilot or the decision functions) as agents, we propose a Petri net model of those conflicting interactions, which allows them to be detected as deadlocks in the Petri net. In order to test our Petri net model, we designed an autoflight system that was formally analysed to detect conflicting situations. We identified three conflicting situations that were integrated in an experimental scenario in a flight simulator with 10 general aviation pilots. The results showed that the conflicts that we had a-priori identified as critical had impacted the pilots' performance. Indeed, the first conflict remained unnoticed by eight participants and led to a potential collision with another aircraft. The second conflict was detected by all the participants but three of them did not manage the situation correctly. The last conflict was also detected by all the participants but provoked typical automation surprise situation as only one declared that he had understood the autopilot behaviour. These behavioural results are discussed in terms of workload and number of fired 'hidden' transitions. Eventually, this study reveals that both formal and experimental approaches are complementary to identify and assess the criticality of human-automation conflicts.Practitioner Summary: We propose a Petri net model of human-automation conflicts. An experiment was conducted with general aviation pilots performing a scenario involving three conflicting situations to test the soundness of our formal approach. This study reveals that both formal and experimental approaches are complementary to identify and assess the criticality conflicts. © 2014 © 2014 Taylor & Francis. Source

Magnan P.,ISAE
Springer Series in Optical Sciences | Year: 2011

Even with the use of powerful optical systems, astronomy and space imaging applications have often to deal with a very limited amount of photons. Despite major achievements brought to these applications by CCD and hybrid narrow gap semiconductor detectors technologies, and as illustrated by large focal planes used in ground based telescopes, the detection limit of classical solid state imaging devices still remains above the single photon level sensitivity required by several applications. Amongst these, attempts to circumvent the atmosphere turbulence effects limiting image quality have lead to the development of the so-called Lucky Imaging technique and wavefront sensors being part of adaptive optics systems. Both are based on imaging devices requiring the use of internal gain (electron multiplication) to lower the readout noise: EMCCDs and Avalanche Amplifiying pnCCDs using silicon and HgCdTe e-APDs for the infrared domain are considered.Space based LIDARs, currently becoming more popular for altimetry and atmosphere characterization, also require single photon sensitivity level in order to reduce the emitted laser pulse energy and/or enhance the measurement accuracy. An example of a dedicated imaging device for atmospheric LIDAR is detailed before concluding on the current status of single photon devices for space applications. © 2011 Springer-Verlag Berlin Heidelberg. Source

De Croon G.,Technical University of Delft | Alazard D.,ISAE | Izzo D.,European Space Agency
IEEE Transactions on Aerospace and Electronic Systems | Year: 2015

Two bioinspired landing strategies are studied. Both strategies enforce a constant ventral optic flow with constantly decreasing time-to-contact or exponentially decreasing time-to-contact. Until now these strategies have only been studied assuming the visual quantities to be known, i.e., without sensor noise and delay. In this study, the control laws executing the aforementioned landing strategies are studied both theoretically and empirically, taking into account the actual extraction of the visual cues from images. © 2015 IEEE. Source

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