CNRS Laboratory for Analysis and Architecture of Systems

Toulouse, France

CNRS Laboratory for Analysis and Architecture of Systems

Toulouse, France

The Laboratory for analysis and architecture of systems is a laboratory depending from the Centre national de la recherche scientifique. This facility is located near to other important higher education facilities in Toulouse, France: the Paul Sabatier University, SUPAERO, the ENAC, the INSA, as well as other research centers . Wikipedia.

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Artigues C.,CNRS Laboratory for Analysis and Architecture of Systems
Operations Research Letters | Year: 2017

For non-preemptive scheduling, time-indexed zero–one linear programming formulations have been deeply analyzed. This note clarifies the current knowledge about the strength of these formulations and shows that some formulations that have been proposed “new” in the literature are in fact weaker or equivalent to those already known. Much of the arguments used follow from a Ph.D. thesis by Sousa, which has been largely overlooked in the literature. © 2017 Elsevier B.V.


Franchi A.,CNRS Laboratory for Analysis and Architecture of Systems | Mallet A.,CNRS Laboratory for Analysis and Architecture of Systems
Proceedings - IEEE International Conference on Robotics and Automation | Year: 2017

This paper introduces the adaptive bias and adaptive gain (ABAG) algorithm for closed-loop electronic speed control (ESC) of the brushless direct current (BLDC) motors typically used to spin the propellers in multi-rotor aerial robots. The ABAG algorithm is adaptive and robust in the sense that it does not require the knowledge of any mechanical/electrical parameter of the motor/propeller group and that neither a pre-calibration nor the knowledge of the feedforward/nominal input is needed. The ABAG algorithm is amenable to an extremely low complexity implementation. We experimentally prove that it can run in 27.5 μ» on a 8 MHz microcontroller with no floating point unit and limited arithmetic capabilities allowing only 8-bit additions, subtractions and multiplications. Besides the controller implementation we present a self-contained open source software architecture that handles the entire speed control process, including clock synchronization, and over-current and blockage safeties. The excellent performance and robustness of ABAG are shown by experimental tests and aerial physical interaction experiments. © 2017 IEEE.


Ingrand F.,CNRS Laboratory for Analysis and Architecture of Systems | Ghallab M.,CNRS Laboratory for Analysis and Architecture of Systems
Artificial Intelligence | Year: 2017

Autonomous robots facing a diversity of open environments and performing a variety of tasks and interactions need explicit deliberation in order to fulfill their missions. Deliberation is meant to endow a robotic system with extended, more adaptable and robust functionalities, as well as reduce its deployment cost. The ambition of this survey is to present a global overview of deliberation functions in robotics and to discuss the state of the art in this area. The following five deliberation functions are identified and analyzed: planning, acting, monitoring, observing, and learning. The paper introduces a global perspective on these deliberation functions and discusses their main characteristics, design choices and constraints. The reviewed contributions are discussed with respect to this perspective. The survey focuses as much as possible on papers with a clear robotics content and with a concern on integrating several deliberation functions. © 2014 Elsevier B.V.


Sola J.,CNRS Laboratory for Analysis and Architecture of Systems
Proceedings - IEEE International Conference on Robotics and Automation | Year: 2010

We benchmark in this article three different landmark parametrizations in monocular 6DOF EKF-SLAM. These parametrizations are homogeneous points (HP), inverse-distance points (IDP, better known as inverse-depth), and the new anchored homogeneous points (AHP). The discourse used for describing them is chosen to highlight their differences and similarities, showing that they are just incremental variations of ones with respect to the others. We show for the first time a complete comparison of HP against IDP, two methods that are getting popular, and introduce also for the first time AHP, whose description falls precisely between the other two. The benchmarking is done by running all algorithms on the same data and by using the well-established NEES consistency analysis. Our conclusion is that the new AHP parametrization is the most interesting one for monocular EKF-SLAM (followed by IDP and then HP) because it greatly postpones the apparition of EKF inconsistency. ©2010 IEEE.


Lasserre J.B.,CNRS Laboratory for Analysis and Architecture of Systems
Journal of Global Optimization | Year: 2011

We consider the robust (or min-max) optimization problem J*:=max y∈Ω min x{f(x,y): (x,y) ∈ Δ} where f is a polynomial and Δ ⊂ R n × R p as well as Ω ⊂ R p are compact basic semi-algebraic sets. We first provide a sequence of polynomial lower approximations (J i) ⊂ R[y] of the optimal value function J(y):= min x{f(x,y): (x,y) ∈ Δ. The polynomial J i ∈ R[y] is obtained from an optimal (or nearly optimal) solution of a semidefinite program, the ith in the "joint + marginal" hierarchy of semidefinite relaxations associated with the parametric optimization problem y → J(y), recently proposed in Lasserre (SIAM J Optim 20, 1995-2022, 2010). Then for fixed i, we consider the polynomial optimization problem J* i:= max y{J i(y): y ∈ Ω and prove that J^* i(:= max l=1,...,iJ* l) converges to J*as i → ∞. Finally, for fixed l ≤ i, each J^* l (and hence J^* i) can be approximated by solving a hierarchy of semidefinite relaxations as already described in Lasserre (SIAM J Optim 11, 796-817, 2001; Moments, Positive Polynomials and Their Applications. Imperial College Press, London 2009). © 2010 Springer Science+Business Media, LLC.


Lasserre J.B.,CNRS Laboratory for Analysis and Architecture of Systems
SIAM Journal on Optimization | Year: 2010

Given a compact parameter set Y ⊂ ℝp, we consider polynomial optimization problems (Py) on Rn whose description depends on the parameter y ∈ Y. We assume that one can compute all moments of some probability measure φ on Y, absolutely continuous with respect to the Lebesgue measure (e.g., Y is a box or a simplex and φ is uniformly distributed). We then provide a hierarchy of semidefinite relaxations whose associated sequence of optimal solutions converges to the moment vector of a probability measure that encodes all information about all global optimal solutions x*(y) of Py, as y ∈ Y. In particular, one may approximate as closely as desired any polynomial functional of the optimal solutions like, e.g., their φ-mean. In addition, using this knowledge on moments, the measurable function y-→ x*k(y) of the kth coordinate of optimal solutions, can be estimated, e.g., by maximum entropy methods. Also, for a boolean variable xk, one may approximate as closely as desired its persistency φ({y : x* k(y) = 1}, i.e., the probability that in an optimal solution x* (y), the coordinate x* k(y) takes the value 1. Last but not least, from an optimal solution of the dual semidefinite relaxations, one provides a sequence of polynomial (resp., piecewise polynomial) lower approximations with L1(φ) (resp., φ-almost uniform) convergence to the optimal value function. Copyright © 2010, Society for Industrial and Applied Mathematics.


Lasserre J.B.,CNRS Laboratory for Analysis and Architecture of Systems
Mathematics of Operations Research | Year: 2013

We consider the inverse optimization problem associated with the polynomial program f* = min{f(x): x ε K} and a given current feasible solution y ε K. We provide a systematic numerical scheme to compute an inverse optimal solution. That is, we compute a polynomial f (which may be of the same degree as f , if desired) with the following properties: (a) y is a global minimizer of f on K with a Putinar's certificate with an a priori degree bound d fixed, and (b) fQ minimizes ||f -f|| (which can be the l1, l 2 or l∞ -norm of the coefficients) over all polynomials with such properties. Computing fQd reduces to solving a semidefinite program whose optimal value also provides a bound on how far f (y) is from the unknown optimal value f*. The size of the semidefinite program can be adapted to the available computational capabilities. Moreover, if one uses the l1-norm, then f takes a simple and explicit canonical form. Some variations are also discussed. © 2013 INFORMS.


Mansard N.,CNRS Laboratory for Analysis and Architecture of Systems
Proceedings - IEEE International Conference on Robotics and Automation | Year: 2012

The most classical solution to generate whole-body motions on humanoid robots is to use the inverse kinematics on a set of tasks. It enables flexibility, repeatability, sensor-feedback if needed, and can be applied in real time onboard the robot. However, it cannot comprehend the whole complexity of the robot dynamics. Inverse dynamics is then a mandatory evolution. Before application as a generic motion generator, two important concerns need to be solved. First, when including in the motion-generation problem the forces and torques variables, the numerical conditioning can become very low, inducing undesired behaviors or even divergence. Second, the computational costs of the problem resolution is much more important than when considering the kinematics alone. This paper proposes a complete reformulation of the inverse-dynamics problem, by cutting the ill-conditioned part of the problem, solving in a same way the problem of numerical stability and of cost reduction. The approach is validated by a set of dynamic whole-body movements of the HRP-2 robot. © 2012 IEEE.


Patent
CNRS Laboratory for Analysis, Architecture of Systems and Atmel Corporation | Date: 2010-08-05

A p-channel LDMOS device with a controlled n-type buried layer (NBL) is disclosed. A Shallow Trench Isolation (STI) oxidation is defined, partially or totally covering the drift region length. The NBL layer, which can be defined with the p-well mask, connects to the n-well diffusion, thus providing an evacuation path for electrons generated by impact ionization. High immunity to the Kirk effect is also achieved, resulting in a significantly improved safe-operating-area (SOA). The addition of the NBL deep inside the drift region supports a space-charge depletion region which increases the RESURF effectiveness, thus improving BV. An optimum NBL implanted dose can be set to ensure fully compensated charge balance among n and p doping in the drift region (charge balance conditions). The p-well implanted dose can be further increased to maintain a charge balance, which leads to an Rdson reduction.


Patent
CNRS Laboratory for Analysis, Architecture of Systems and Atmel Corporation | Date: 2012-06-29

A p-channel LDMOS device with a controlled n-type buried layer (NBL) is disclosed. A Shallow Trench Isolation (STI) oxidation is defined, partially or totally covering the drift region length. The NBL layer, which can be defined with the p-well mask, connects to the n-well diffusion, thus providing an evacuation path for electrons generated by impact ionization. High immunity to the Kirk effect is also achieved, resulting in a significantly improved safe-operating-area (SOA). The addition of the NBL deep inside the drift region supports a space-charge depletion region which increases the RESURF effectiveness, thus improving BV. An optimum NBL implanted dose can be set to ensure fully compensated charge balance among n and p doping in the drift region (charge balance conditions). The p-well implanted dose can be further increased to maintain a charge balance, which leads to an Rdson reduction.

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