Proofs of Control of a Quadrotor and a Ground Vehicle Manipulating an Object

This paper focuses on the control of a cooperative system composed of an Unmanned Aerial Vehicle (UAV) and an Unmanned Ground Vehicle (UGV) manipulating an object. The two units are subject to input saturations and collaborate to move the object to a desired pose characterized by its position and inclination. The dynamics are derived using Euler-Lagrange method. A pre-stabilizing control law is proposed where the UGV is tasked to deploy the object to a certain position whereas the UAV adjusts its inclination. In particular, a proportional-derivative control law is proposed for the UGV, and a cascade control approach is used for the UAV, where the inner loop controls the attitude of the UAV and the outer loop stabilizes the inclination of the object. Then, we prove the stability of the points of equilibrium using small gain arguments. To ensure constraints satisfaction at all times, a reference governor unit is added to the pre-stabilizing control scheme. Finally, numerical results combined with experimental results are provided to validate the effectiveness of the proposed control scheme in practice.Comment: 16 pages, 7 figure

Provably Secure Mobile Key Exchange: Applying the Canetti-Krawczyk Approach

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Modeling the phase equilibria of refrigerant fluids with the COSMO-SAC and COSMO-RS approaches. Application to process simulation

International audienceOn account of the constraints imposed by the European and International legislations, the refrigerant industry must constantly find alternative refrigerant fluids that have lower impacts on the global warming of Earth and Ozone layer. Working with refrigerant blends is often preferable to pure component fluids for energy saving and flexibility of operation. In order to select the optimal mixture composition for the design and operation of a refrigeration process, it is necessary to know the phase diagram and thermodynamic properties of mixtures. Vapor-liquid equilibria (VLE) and the location of azeotropes must be accurately known. In this work three different thermodynamic models based on the COSMO approach have been used to predict the phase equilibria of mixtures of refrigerant molecules: the COSMO-RS model developed by Klamt and co workers [1, 2], the 2002 version of COSMO-SAC model [3], and the COSMO-SAC-dsp model [4] that includes a dispersion term. The vapor-liquid equilibria can be reasonably well predicted by the COSMO-RS model, however bad predictions are obtained with COSMO-SAC 2002. In particular, the COSMO-SAC model is unable to predict the azeotropic behavior observed in mixtures of alkanes and fluorinated molecules. By adjusting some universal parameters, it is possible to obtain reasonable predictions with the COSMO-SAC dsp model

How Amphipols Embed Membrane Proteins: Global Solvent Accessibility and Interaction with a Flexible Protein Terminus

Amphipathic polymers called amphipols provide a valuable alternative to detergents for keeping integral membrane proteins soluble in aqueous buffers. Here, we characterize spatial contacts of amphipol A8-35 with membrane proteins from two architectural classes: The 8-stranded β-barrel outer membrane protein OmpX and the α-helical protein bacteriorhodopsin. OmpX is well structured in A8-35, with its barrel adopting a fold closely similar to that in dihexanoylphosphocholine micelles. The accessibility of A8-35-trapped OmpX by a water-soluble paramagnetic molecule is highly similar to that in detergent micelles and resembles the accessibility in the natural membrane. For the α-helical protein bacteriorhodopsin, previously shown to keep its fold and function in amphipols, NMR data show that the imidazole protons of a polyhistidine tag at the N-terminus of the protein are exchange protected in the presence of detergent and lipid bilayer nanodiscs, but not in amphipols, indicating the absence of an interaction in the latter case. Overall, A8-35 exhibits protein interaction properties somewhat different from detergents and lipid bilayer nanodiscs, while maintaining the structure of solubilized integral membrane proteins

Quantitative real-time analysis of the efflux by the MacAB-TolC tripartite efflux pump clarifies the role of ATP hydrolysis within mechanotransmission mechanism

Tripartite efflux pumps built around ATP-binding cassette (ABC) transporters are membrane protein machineries that perform vectorial export of a large variety of drugs and virulence factors from Gram negative bacteria, using ATP-hydrolysis as energy source. Determining the number of ATP molecules consumed per transport cycle is essential to understanding the efficiency of substrate transport. Using a reconstituted pump in a membrane mimic environment, we show that MacAB-TolC from Escherichia coli couples substrate transport to ATP-hydrolysis with high efficiency. Contrary to the predictions of the currently prevailing “molecular bellows” model of MacB-operation, which assigns the power stroke to the ATP-binding by the nucleotide binding domains of the transporter, by utilizing a novel assay, we report clear synchronization of the substrate transfer with ATP-hydrolysis, suggesting that at least some of the power stroke for the substrate efflux is provided by ATP-hydrolysis. Our findings narrow down the window for energy consumption step that results in substrate transition into the TolC-channel, expanding the current understanding of the efflux cycle of the MacB-based tripartite assemblies. Based on that we propose a modified model of the MacB cycle within the context of tripartite complex assembly

Real-Time Estimation of Weld Quality in Continuous Strip Lines

In some steel production lines the strips coming from the successive coils are welded in order to obtain an infinite strip. In such industrial plants, welding is a critical task, because of the costs induced by a weld breakage on the line. Currently, the weld quality is estimated by the operator, by visualising it and making a hammer test. This paper proposes an automatic method for improving the diagnosis of seam weld. The proposed methodology is divided into two parts. The first one consists in assessing the weld by means of indicators computed from the evolution of the process variables. These indicators are then compared to thresholds which are systematically determined thanks to a database corresponding to thousands of welds. The second part deals with the detection of weld opening and centring problems by means of indicators obtained from the position measurements and the strip widths.info:eu-repo/semantics/publishe

Control of a quadrotor and a ground vehicle manipulating an object

This paper focuses on the control of a cooperative system composed of an Unmanned Aerial Vehicle (UAV) and an Unmanned Ground Vehicle (UGV) manipulating an object. The two units are subject to input saturations and collaborate to move the object to a desired pose characterized by its position and inclination. The dynamics are derived using the Euler–Lagrange method. A stabilizing control law is proposed where the UGV is tasked to deploy the object to a certain position whereas the UAV adjusts its inclination. In particular, a proportional–derivative control law is proposed for the UGV, and a cascade control is used for the UAV, where the inner loop controls the attitude of the UAV and the outer loop stabilizes the inclination of the object. The stability of the points of equilibrium is proven using small gain arguments. To ensure constraints satisfaction at all times, a reference governor unit is added to this stabilizing control law. Simulations and experimental results are provided to validate the effectiveness of the proposed control scheme.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Disturbance-Observer-Based User Force Estimation for Bilateral Teleoperated Needle Insertion

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Identification of a hybrid model for simulation of the instrument trocar interaction force

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Simulation and implementation of bilateral teleoperated needle insertion via an endoscope.

info:eu-repo/semantics/publishe