Orientation estimation using low cost sensors is an important task for Micro Aerial Vehicles (MAVs) in order to obtain a good feedback for the attitude controller. The challenges come from the low ...accuracy and noisy data of the MicroElectroMechanical System (MEMS) technology, which is the basis of modern, miniaturized inertial sensors. In this article, we describe a novel approach to obtain an estimation of the orientation in quaternion form from the observations of gravity and magnetic field. Our approach provides a quaternion estimation as the algebraic solution of a system from inertial/magnetic observations. We separate the problems of finding the "tilt" quaternion and the heading quaternion in two sub-parts of our system. This procedure is the key for avoiding the impact of the magnetic disturbances on the roll and pitch components of the orientation when the sensor is surrounded by unwanted magnetic flux. We demonstrate the validity of our method first analytically and then empirically using simulated data. We propose a novel complementary filter for MAVs that fuses together gyroscope data with accelerometer and magnetic field readings. The correction part of the filter is based on the method described above and works for both IMU (Inertial Measurement Unit) and MARG (Magnetic, Angular Rate, and Gravity) sensors. We evaluate the effectiveness of the filter and show that it significantly outperforms other common methods, using publicly available datasets with ground-truth data recorded during a real flight experiment of a micro quadrotor helicopter.
Real-time orientation estimation using low-cost inertial sensors is essential for all the applications where size and power consumption are critical constraints. Such applications include robotics, ...human motion analysis, and mobile devices. This paper presents a linear Kalman filter for magnetic angular rate and gravity sensors that processes angular rate, acceleration, and magnetic field data to obtain an estimation of the orientation in quaternion representation. Acceleration and magnetic field observations are preprocessed through a novel external algorithm, which computes the quaternion orientation as the composition of two algebraic quaternions. The decoupled nature of the two quaternions makes the roll and pitch components of the orientation immune to magnetic disturbances. The external algorithm reduces the complexity of the filter, making the measurement equations linear. Real-time implementation and the test results of the Kalman filter are presented and compared against a typical quaternion-based extended Kalman filter and a constant gain filter based on the gradient-descent algorithm.
•A demand-side approach to the location of charging infrastructure problem is discussed in the paper.•The analysis is based on a large data-set of private vehicle travels within the urban area of ...Rome.•Cluster analysis is applied to the data to find the optimal location zones for charging infrastructures.•The daily energy demand and the average number of users per day are calculated for each and every charging infrastructure.
Despite all the acknowledged advantages in terms of environmental impact reduction, energy efficiency and noise reduction, the electric mobility market is below expectations. In fact, electric vehicles have limitations that pose several important challenges for achieving a sustainable mobility system: among them, the availability of an adequate charging infrastructure is recognized as a fundamental requirement and appropriate approaches to optimize public and private investments in this field are to be delineated. In this paper we consider actual data on conventional private vehicle usage in the urban area of Rome to carry out a strategy for the optimal allocation of charging infrastructures into portions (subareas) of the urban area, based on an analysis of a driver sample under the assumption of a complete switch to an equivalent fleet of electric vehicles. Moreover, the energy requirement for each one of the subareas is estimated in terms of the electric energy used by the equivalent fleet of electric vehicles to reach their destination. The model can be easily generalized to other problems regarding facility allocation based on user demand.
Underserved Hispanic patients often experience unmet palliative care (PC) needs, particularly those with noncancer diagnoses such as Alzheimer's disease and related dementias. Most caregivers for ...Hispanic patients are family relatives who are less likely to use health care and community resources and experience high caregiver burden. We adapted a culturally tailored patient navigator (PN) intervention to provide support and improve PC outcomes for Hispanics with Alzheimer's disease and related dementias and their family caregivers (FCGs).
To explore Hispanic FCGs' experiences and perceptions of caregiving for a loved one, and how our PN intervention impacted their needs.
Qualitative descriptive.
FCG participants (
= 10) from our randomized control trial's intervention group were recruited from academic and safety net hospitals and community-based clinics across urban and rural Colorado in the United States.
Data obtained from individual, semistructured, 30-minute telephone interviews were recorded, transcribed, translated, and analyzed using NVivo and qualitative thematic analyses.
Four major themes emerged:
and
. Subthemes highlighted differing definitions of "contributing," role resentment, and interpersonal issues. Varying familial expectations underscore FCG strain when the burden of caregiving is not shared. Participants used various coping strategies as necessary support and gained awareness through education, guidance, and referrals to resources.
PNs helped FCGs and patients beyond the intervention's scope. Providing support and awareness to FCGs, and incorporating cultural beliefs, may improve PC access to disparate populations and guide future interventions. Clinical Trial Registration Number NCT03181750.
This paper focuses on the role of hyperbolicity on pattern formation in the subcritical regime for a class of hyperbolic models with cross-diffusion. A weakly nonlinear analysis up to the fifth order ...is employed to describe the time evolution of the pattern amplitude close to the instability threshold. The effects of the inertial times on the pattern formation as well as on the transient subcritical regime are investigated, both analitically and numerically, in the case of the hyperbolic Schnakenberg model.
We describe the design and 3D sensing performance of an omnidirectional stereo (omnistereo) vision system applied to Micro Aerial Vehicles (MAVs). The proposed omnistereo sensor employs a monocular ...camera that is co-axially aligned with a pair of hyperboloidal mirrors (a vertically-folded catadioptric configuration). We show that this arrangement provides a compact solution for omnidirectional 3D perception while mounted on top of propeller-based MAVs (not capable of large payloads). The theoretical single viewpoint (SVP) constraint helps us derive analytical solutions for the sensor's projective geometry and generate SVP-compliant panoramic images to compute 3D information from stereo correspondences (in a truly synchronous fashion). We perform an extensive analysis on various system characteristics such as its size, catadioptric spatial resolution, field-of-view. In addition, we pose a probabilistic model for the uncertainty estimation of 3D information from triangulation of back-projected rays. We validate the projection error of the design using both synthetic and real-life images against ground-truth data. Qualitatively, we show 3D point clouds (dense and sparse) resulting out of a single image captured from a real-life experiment. We expect the reproducibility of our sensor as its model parameters can be optimized to satisfy other catadioptric-based omnistereo vision under different circumstances.
A hyperbolic model to study effects of industrialization and urbanization on air pollution propagation is proposed.
The existence of smooth and discontinuous traveling wave-like solutions, related to ...the spread of both the pollution in the atmosphere and the level of urbanization, is discussed. Validation of the model in point is also accomplished by searching for numerical solutions of the system of PDEs.
The role played by magnetoelastic effects on the properties exhibited by magnetic domain walls propagating along the major axis of a thin magnetostrictive nanostrip, coupled mechanically with a thick ...piezoelectric actuator, is theoretically investigated. The magnetostrictive layer is assumed to be a linear elastic material belonging to the cubic crystal classes
4
¯
3m, 432 and m
3
¯
m and to undergo isochoric magnetostrictive deformations. The analysis is carried out in the framework of the extended Landau–Lifshitz–Gilbert equation, which allows to describe, at the mesoscale, the spatio-temporal evolution of the local magnetization vector driven by magnetic fields and electric currents, in the presence of magnetoelastic and magnetocrystalline anisotropy fields. Through the traveling-wave transformation, the explicit expression of the key features involved in both steady and precessional regimes is provided and a qualitative comparison with data from the literature is also presented.
•A Stirling rated at 1kWe and 8kWth is analyzed experimentally and numerically.•The developed model is an extension of the work by Urieli and Berchowitz.•The initial pressure of the working fluid ...(nitrogen) is varied from 9 to 24barg.•The initial pressure influences strongly the fuel input and the electrical power.•Major losses: wall heat conduction and non-unitary regenerator effectiveness.
Micro-cogeneration Stirling units are promising for residential applications because of high total efficiencies, favorable ratios of thermal to electrical powers and low CO as well as NOx emissions. This work focuses on the experimental and the numerical analysis of a commercial unit generating 8kW of hot water (up to 15kW with an auxiliary burner) and 1kW of electricity burning natural gas. In the experimental campaign, the initial pressure of the working fluid is changed in a range from 9 to 24barg – 20barg being the nominal value – while the inlet temperature of the water loop and its mass flow rate are kept at the nominal conditions of, respectively, 50°C and 0.194kg/s. The experimental results indicate clearly that the initial pressure of the working fluid – Nitrogen – affects strongly the net electrical power output and efficiency. The best performance for the output and efficiency of 943W and 9.6% (based on the higher heating value of the burnt natural gas) are achieved at 22barg. On the other hand, the thermal power trend indicates a maximum value of 8420W at the working pressure of 24barg, which corresponds to a thermal efficiency of 84.7% (again based on higher heating value). Measurements are coupled to a detailed model based on a modification of the work by Urieli and Berchowitz. Thanks to the tuning with the experimental results, the numerical model allows investigating the profiles of the main thermodynamic parameters and heat losses during the cycle, as well as estimating those physical properties that are not directly measurable. The major losses turn to be the wall parasitic heat conduction from heater to cooler and the non-unitary effectiveness of the regenerator.
This work discusses the design and the development of a Laboratory of Micro-Cogeneration (LMC) at Politecnico di Milano. The LMC laboratory is a unique structure devoted to small-scale power ...generation, with the main goals of testing and improving the performance of systems that produce or utilize electric and thermal (hot and/or cold) power in a very general sense, spanning from combined heat and power (CHP) units to heaters, from absorption chillers to heat pumps, but also able to perform tests on fuel processors and electrolyzers. The laboratory features a supply of natural gas as well as H2 and O2 from a high pressure electrolyzer and of CO, CO2 and N2 from bottles, permitting to carry out experiments with simulated synthesis fuels. The maximum allowable electrical power produced, exported to the grid or to an electronic loadbank, or consumed by the system under test is 100 kW; maximum allowable thermal power is roughly 200 kW with variable temperature water circuits (from chilled water up to a 150 °C at 8 bar superheated water loop). This work outlines also the instruments used for on-line recording of thermodynamic properties, emissions and power, aiming at monitoring and reconstructing mass and energy balances.
One of the first experimental campaign has been carried out on a CHP system based on polymer electrolyte membrane fuel cells (PEM), a promising candidate for distributed CHP thanks to low pollutant emissions and good efficiency, rapid startup and flexibility, although affected by a rather complex fuel processing section to provide the appropriate fuel to the PEM. This work presents the experimental analysis of a 20 kW prototype PEM CHP system complete of natural gas processor. The prototype is operated at LMC to characterize the processing section and the thermodynamic performances of the overall system. Despite its non-optimized layout, the unit has shown encouraging total efficiency (76%) and primary energy saving index (6%).
•It is presented a new Laboratory of Micro-cogeneration systems.•Laboratory layout, infrastructure and instrumentation is discussed.•Test conceptual operation and circuit arrangement are presented.•Test results on a 30 kW CHP unit based on PEM are presented.
PDF
