Practical Model Construction and Stable Control of an Unmanned Aerial Vehicle With a Parafoil-Type Wing

This correspondence paper presents a framework for practical model construction and stable altitude control of an unmanned aerial vehicle with a parafoil-type wing (UAV-PW). To design a stable controller, we first construct a dynamical longitudinal model of the UAV-PW. Since there exist no aerodynamics data of the parafoil shape in our UAV-PW, aerodynamics coefficients balanced at the trimmed equilibrium are employed. The model accuracy is investigated by comparing the model outputs with the real test flight experimental data. Next, stable controller design conditions for the UAV-PW model with uncertainties are derived in terms of linear matrix inequalities (LMIs). By solving the LMI conditions, we design a stable controller that asymptotically stabilizes the UAV-PW model with the uncertainties on a considered operation domain. The experimental results demonstrate the viability of the model construction and the stable altitude control

A Waypoint Following Control Design for a Paraglider Model With Aerodynamic Uncertainty

This paper presents a waypoint following control design for a powered paraglider (PPG) model. After constructing a dynamic model with six degrees of freedom of the PPG, a dynamical lateral model around a trim equilibrium in the steady-state flight is obtained. Unknown parameters, such as the moment of inertia, the drag coefficient, etc., in the lateral model are optimized by real flight experimental data. The model output with the optimized parameters agrees with the real flight experimental data. Since the aerodynamics-related parameter, i.e., the drag coefficient, might be slightly changed even near the considered trim equilibrium, this paper considers its uncertainty in the constructed lateral model. A nonlinear controller to stabilize the lateral model (with the aerodynamic uncertainty) on a considered operation domain is designed by solving robust controller design conditions expressed in terms of linear matrix inequality. The experimental results including automatic landing demonstrate the effectiveness of the control system design framework, i.e., the model construction and the robust stable control, considering the model uncertainty

On the magnon interaction in Haematite. 2: Magnon energy of the acoustical mode and magnetic critical fields

Previous spin wave theories of the antiferromagnet hematite were extended. The behavior of thermodynamic quantities around the Morin transition temperature was studied, and the latent heat of the Morin transition was calculated. The temperature dependence of the antiferromagnetic resonance frequency and the parallel and perpendicular critical spin-flop magnetic fields were calculated. It was found that the theory agrees well with experiment

Field-Induced Magnetic Order and Simultaneous Lattice Deformation in TlCuCl3

We report the results of Cu and Cl nuclear magnetic resonance experiments (NMR) and thermal expansion measurements in magnetic fields in the coupled dimer spin system TlCuCl3. We found that the field-induced antiferromagnetic transition as confirmed by the splitting of NMR lines is slightly discontinuous. The abrupt change of the electric field gradient at the Cl sites, as well as the sizable change of the lattice constants, across the phase boundary indicate that the magnetic order is accompanied by simultaneous lattice deformation.Comment: 4 pages, 5 figure

The magnetization process of the spin-one triangular-lattice Heisenberg antiferromagnet

We apply the coupled cluster method and exact diagonalzation to study the uniform susceptibility and the ground-state magnetization curve of the triangular-lattice spin-1 Heisenberg antiferromagnet. Comparing our theoretical data for the magnetization curve with recent measurements on the s=1 triangular lattice antiferromagnet Ba3NiSb2O9 we find a very good agreement.Comment: 2 pages, 3 figure

A New Sum-of-Squares Design Framework for Robust Control of Polynomial Fuzzy Systems With Uncertainties

This paper presents a new sum-of-squares (SOS, for brevity) design framework for robust control of polynomial fuzzy systems with uncertainties. Two kinds of robust stabilization conditions are derived in terms of SOS. One is global SOS robust stabilization conditions that guarantee the global and asymptotical stability of polynomial fuzzy control systems. The other is semiglobal SOS robust stabilization conditions. The latter is available for very complicated systems that are difficult to guarantee the global and asymptotical stability of polynomial fuzzy control systems. The main feature of all the SOS robust stabilization conditions derived in this paper are to be expressed as nonconvex formulations with respect to polynomial Lyapunov function parameters and polynomial feedback gains. Since a typical transformation from nonconvex SOS design conditions to convex SOS design conditions often results in some conservative issues, the new design framework presented in this paper gives key ideas to avoid the conservative issues. The first key idea is that we directly solve nonconvex SOS design conditions without applying the typical transformation. The second key idea is that we bring a so-called copositivity concept. These ideas provide some advantages in addition to relaxations. To solve our SOS robust stabilization conditions efficiently, we introduce a gradient algorithm formulated as a minimizing optimization problem of the upper bound of the time derivative of an SOS polynomial that can be regarded as a candidate of polynomial Lyapunov functions. Three design examples are provided to illustrate the validity and applicability of the proposed design framework. The examples demonstrate advantages of our new SOS design framework for the existing linear matrix inequality approaches and the existing convex SOS approach

Polynomial Fuzzy Observer Designs: A Sum-of-Squares Approach

This paper presents a simple passive attitude stabilizer (PAS) for vision-based stabilization of palm-size aerial vehicles. First, a mathematical dynamic model of a palm-size aerial vehicle with the proposed PAS is constructed. Stability analysis for the dynamics is carried out in terms of Lyapunov stability theory. The analysis results show that the proposed stabilizer guarantees passive stabilizing behavior, i.e., passive attitude recovering, of the aerial vehicle for small perturbations from a stability theory point of view. Experimental results demonstrate the utility of the proposed PAS for the aerial vehicle

Classical and quantum quasi-free position dependent mass; P\"oschl-Teller and ordering-ambiguity

We argue that the classical and quantum mechanical correspondence may play a basic role in the fixation of the ordering-ambiguity parameters. We use quasi-free position-dependent masses in the classical and quantum frameworks. The effective P\"oschl-Teller model is used as a manifested reference potential to elaborate on the reliability of the ordering-ambiguity parameters available in the literature.Comment: 10 page

Seasonal cycles of ozone and oxidized nitrogen species in northeast Asia - 2:A model analysis of the roles of chemistry and transport

[1] The dominant factors controlling the seasonal variations of ozone (O-3) and three major oxidized nitrogen species, peroxyacetyl nitrate (PAN), nitrogen oxides (NOx), and nitric acid (HNO3), in northeast Asia are investigated by using a three-dimensional global chemical transport model to analyze surface observations made at Rishiri Island, a remote island in northern Japan. The model was evaluated by comparing with observed seasonal variations, and with the relationships between O-3, CO, and PAN. We show that the model reproduces the chemical environment at Rishiri Island reasonably well, and that the seasonal cycles of O-3, CO, NOy species, and VOCs are well predicted. The impact of local emissions on some of these constituents is significant, but is not the dominant factor affecting the seasonal cycles. The seasonal roles of chemistry and transport in controlling O-3 and PAN are revealed by examining production/ destruction and import/ export/deposition fluxes in the boundary layer over the Rishiri region. For O-3, transport plays a key role throughout the year, and the regional photochemical contribution is at most 10% in summer. For PAN, in contrast, transport dominates in winter, while in-situ chemistry contributes as much as 75% in summer. It is suggested that the relative contribution of transport and in-situ chemistry is significantly different for O-3 and PAN, but that the wintertime dominance of transport due to the long chemical lifetimes of these species is sufficient to drive the seasonal cycles of springtime maximum and summertime minimum characteristic of remote sites