Backstepping and Sliding-mode Techniques Applied to an Indoor Micro Quadrotor

The latest technological progress in sensors, actuators and energy storage devices enables the developments of miniature VTOL systems. In this paper we present the results of two nonlinear control techniques applied to an autonomous micro helicopter called Quadrotor. A backstepping and a sliding-mode techniques. We performed various simulations in open and closed loop and implemented several experiments on the test-bench to validate the control laws. Finally, we discuss the results of each approach. These developments are part of the OS4 project in our lab

Transition from Steady to Oscillatory Flow Natural Convection of Low-Pr Fluids in 3D Bridgman Configuration for Crystal Growth

A numerical study of the transition from steady to oscillatory flow natural convection of low- Prandtl number fluids inside the 3D Bridgman configuration has been carried out. The three-dimensional Navier-Stokes and energy equations, with the Boussinesq approximation have been discretized by means of a finite volume procedure which employs a second order accurate central difference scheme to treat diffusive and convective fluxes. In natural convection, the buoyancy force is only driving the flow and its intensity can be move a harmful effect on the crystal growth, such as the striation. Naturally, the steady state flow is obtained for low Rayleigh number and shows a great dependence between the Rayleigh number, the flow structure and the heat transfer rate. A low increase in the Rayleigh number we guide to determine the critical point in which the 3D flow became oscillatory. This regime appears by a sinusoidal signal in the time and developed in each period of time

Design and Control of an Indoor Micro Quadrotor

Recent progress in sensor technology, data processing and integrated actuators has made the development of miniature flying robots fully possible. Micro VTOL1 systems represent a useful class of flying robots because of their strong capabilities for small-area monitoring and building exploration. In this paper we describe the approach that our lab2 has taken to micro VTOL evolving towards full autonomy, and present the mechanical design, dynamic modelling, sensing, and control of our indoor VTOL autonomous robot OS43

Combination between the Inclinations of the Enclosure and the Magnetic Field Orientation on the Oscillatory Natural Convection

In this paper, we study the combination between the inclinations of the enclosure and the magnetic field orientation on the oscillatory natural convection. For this, a cylindrical enclosure filled with electrically conducting fluid, has an aspect ratio equal to 2, and subjected to a vertical temperature gradient and different uniform magnetic field orientations were considered. The finite volume method is used to discretize the equations of continuity, momentum and energy. Our computer program based on the SIMPLER Algorithm has a good agreement with available experimental and numerical results. The time-dependent flow and temperature field are presented in oscillatory state, for different cases: inclination of the cylinder, under the effect of magnetic field in different orientations (δ = 0°, 30°, 45° and 90°) and the combination between them. The results are presented at various inclinations of the cylinder (φ = 0°, 30° and 45°), and the Hartmann numbers Ha ≤ 50. The stability diagrams of the dependence between the complicated situations with the value of the critical Grashof number Grcr and corresponding frequency Frcr, are established according to the numerical results of this investigation. The combination between the studied state has a significant effect on the stabilization of the convective flow, and shows that the best stabilization of oscillatory natural convection is obtained at the inclination of the cylinder φ = 30°, and the applied of radial magnetic field (δ = 0°)

Towards Autonomous Indoor Micro VTOL

ISSN:0929-5593ISSN:1573-752

PID vs LQ Control Techniques Applied to an Indoor Micro Quadrotor

The development of miniature flying robots has become a reachable dream thanks to the new sensing and actuating technologies. Micro VTOL1 systems represent a useful class of flying robots because of their strong abilities for small-area monitoring and building exploration. In this paper, we present the results of two model-based control techniques applied to an autonomous four-rotor micro helicopter called Quadrotor. A classical approach (PID) assuming a simplified dynamics and a modern technique (LQ), based on a more complete model. Various simulations were performed and several tests on the bench validate the control laws. Finally, we present the results of the first test in flight with the helicopter released. These developments are part of the OS42 project in our lab3

GIMAP6 is required for T cell maintenance and efficient autophagy in mice

The GTPases of the immunity-associated proteins (GIMAP) GTPases are a family of proteins expressed strongly in the adaptive immune system. We have previously reported that in human cells one member of this family, GIMAP6, interacts with the ATG8 family member GABARAPL2, and is recruited to autophagosomes upon starvation, suggesting a role for GIMAP6 in the autophagic process. To study this possibility and the function of GIMAP6 in the immune system, we have established a mouse line in which the Gimap6 gene can be inactivated by Cre-mediated recombination. In mice bred to carry the CD2Cre transgene such that the Gimap6 gene was deleted within the T and B cell lineages there was a 50-70% reduction in peripheral CD4(+) and CD8(+) T cells. Analysis of splenocyte-derived proteins from these mice indicated increased levels of MAP1LC3B, particularly the lipidated LC3-II form, and S405-phosphorylation of SQSTM1. Electron microscopic measurements of Gimap6(-/-) CD4(+) T cells indicated an increased mitochondrial/cytoplasmic volume ratio and increased numbers of autophagosomes. These results are consistent with autophagic disruption in the cells. However, Gimap6(-/-) T cells were largely normal in character, could be effectively activated in vitro and supported T cell-dependent antibody production. Treatment in vitro of CD4(+) splenocytes from GIMAP6(fl/fl) ERT2Cre mice with 4-hydroxytamoxifen resulted in the disappearance of GIMAP6 within five days. In parallel, increased phosphorylation of SQSTM1 and TBK1 was observed. These results indicate a requirement for GIMAP6 in the maintenance of a normal peripheral adaptive immune system and a significant role for the protein in normal autophagic processes. Moreover, as GIMAP6 is expressed in a cell-selective manner, this indicates the potential existence of a cell-restricted mode of autophagic regulation.Peer reviewe

SKY-SAILOR Design of an autonomous solar powered martian airplane

For more than two decades, Mars has been of great interest for scientific exploration, using orbiting spacecrafts or landers. Orbiters like Mars Express cover large areas and give images of the surface with a resolution limited to several meters. Rovers missions, like Pathfinder or MER, offer the ability to maneuver to scientifically interesting sites, perform analysis of soil and rock composition, but are limited in range to the immediate surroundings of the landing site. There is a strategic gap for systems that would combine high-resolution imagery and extensive coverage. This gap can be addressed by micro-airplanes that will give more accurate images than satellites, thanks to their proximity to the ground (about 0.5 to 2 km) and cover much larger areas than rovers without being limited by terrain roughness. This paper presents a feasibility study and the first design of a very lightweight solar powered airplane for Mars exploration. Called Sky-Sailor, it was investigated in an ESA definition study within the framework of the Startiger technology program