Search results for "traje"
showing 10 items of 382 documents
Hierarchical fuzzy/Lyapunov control for horizontal plane trajectory tracking of underactuated AUV
2010
A new hierarchical closed loop fuzzy control system for horizontal plane trajectory tracking of underactuated Autonomous Underwater Vehicles (AUV) is presented. A model for the AUV is formulated introducing a polar coordinates transformation for the velocities in the body fixed frame. It is employed to control the unactuated sway direction, the longitudinal position and the yaw by using the surge force and the yaw torque only. The highest level control is developed by employing a fuzzy inference system for obtaining the guidance control laws. The properties of the fuzzy system ensure forward surge velocity, fast convergence and Lyapunov's stability of the motion errors. A new low level kine…
Numerical analysis of dynamical systems: unstable periodic orbits, hidden transient chaotic sets, hidden attractors, and finite-time Lyapunov dimensi…
2018
In this article, on the example of the known low-order dynamical models, namely Lorenz, Rossler and Vallis systems, the difficulties of reliable numerical analysis of chaotic dynamical systems are discussed. For the Lorenz system, the problems of existence of hidden chaotic attractors and hidden transient chaotic sets and their numerical investigation are considered. The problems of the numerical characterization of a chaotic attractor by calculating finite-time time Lyapunov exponents and finite-time Lyapunov dimension along one trajectory are demonstrated using the example of computing unstable periodic orbits in the Rossler system. Using the example of the Vallis system describing the El…
A new fuzzy robust dynamic controller for autonomous vehicles with nonholonomic constraints
2005
Abstract In this paper a novel algorithm with a dynamic fuzzy controller applied to the control of trajectory of vehicles with two independent wheels is proposed. An automatic control of trajectory of a vehicle can behave in a not efficient way. It is necessary to consider the friction of the actuators and possible perturbations coming from the outside environment, as for instance the variable characteristics of the ground where the vehicle moves. These perturbations, which depend also on the contact between the wheel and the ground, involve violations of nonholonomic constraints. Thus it is necessary to compensate for these perturbations to obtain a robust control system. The controller sy…
Trajectory Decentralized Fuzzy Control of Multiple UAVs.
2008
This paper considers a complete position and heading rate control system for multiple unmanned aerial vehicles (UAVs) with constant altitude. A decentralized trajectory planning algorithm is proposed, where the UAVs will avoid collisions while moving. In order to stabilize the UAVs in the reference planned trajectories and ensure the boundedness of the control velocities, a fuzzy control law is proposed with Lyapunov's stability proof. Simulation experiments developed in Matlab environment confirm the effectiveness and the robustness of the proposed control algorithm with respect to possible turbulence disturbances perturbing the nominal motion of the UAVs.
The relationship between Polypharmacy and Trajectories of Cognitive Decline in People with Dementia: a large representative cohort study
2019
Polypharmacy, defined through the number of medications prescribed, has been linked to a range of adverse health outcomes in people with dementia. It is however unclear whether a numerical threshold of concurrently prescribed drugs is a suitable predictor for cognitive decline. We aimed to test associations between polypharmacy and both short-term (six months) and long-term (three years) cognitive trajectories in patients with incident dementia. Using data from a large mental health and dementia care database in South London, a cohort of 12,148 patients (mean age = 80.7 years, 61.1% female, mean MMSE = 18.6) clinically diagnosed with dementia was identified. We determined the number of medi…
Midlife Cardiovascular Status and Old Age Physical Functioning Trajectories in Older Businessmen
2019
Objectives The associations between cardiovascular disease (CVD) risk and later physical functioning have been observed, but only a few studies with follow-up into old age are available. We investigated the association between cardiovascular status in midlife and physical functioning trajectories in old age. Design Prospective cohort study. Setting Helsinki Businessmen Study. Participants We studied white men born between 1919 and 1934 in the Helsinki Businessmen Study (HBS, initial n = 3490). Measurements Three CVD status groups were formed based on clinical measurements carried out in 1974: signs of CVD (diagnosed clinically or with changes in ECG, chronic disease present or used medicati…
A data mining approach for grouping and analyzing trajectories of care using claim data: the example of breast cancer
2013
International audience; BACKGROUND: With the increasing burden of chronic diseases, analyzing and understanding trajectories of care is essential for efficient planning and fair allocation of resources. We propose an approach based on mining claim data to support the exploration of trajectories of care. METHODS: A clustering of trajectories of care for breast cancer was performed with Formal Concept Analysis. We exported Data from the French national casemix system, covering all inpatient admissions in the country. Patients admitted for breast cancer surgery in 2009 were selected and their trajectory of care was recomposed with all hospitalizations occuring within one year after surgery. Th…
Life-course leisure-time physical activity trajectories in relation to health-related behaviors in adulthood: the Cardiovascular Risk in Young Finns …
2021
Background Evidence on whether leisure-time physical activity (LTPA) facilitates individuals’ adoption of multiple healthy behaviors remains scarce. This study investigated the associations of diverse longitudinal LTPA trajectories from childhood to adulthood with diet, screen time, smoking, binge drinking, sleep difficulties, and sleep duration in adulthood. Methods Data were drawn from the Cardiovascular Risk in Young Finns Study. Participants were aged 9–18 years (N = 3553; 51% females) in 1980 and 33–49 years at the latest follow-up in 2011. The LTPA trajectories were identified using a latent profile analysis. Differences in self-reported health-related behaviors across the LTPA trajec…
Longitudinal physical activity trajectories from childhood to adulthood and their determinants: The Young Finns Study
2018
Determining lifelong physical activity (PA) trajectories and their determinants is essential to promote a physically active lifestyle throughout the life-course. We aimed to identify PA trajectories from childhood to midlife and their determinants in a longitudinal population-based cohort. This study is a part of the Cardiovascular Risk in Young Finns Study. From 1980, a population-based cohort (N = 3596; 1764 boys/1832 girls, age 3-18 years) has been followed up for 31 years. PA indices were formed based on self-reported data (between age 9-49 years) on frequency, duration, and intensity of leisure (during childhood) or high-intensity (at later age) PA and on sports club participation/comp…
Associations of Leisure-Time Physical Activity Trajectories with Fruit and Vegetable Consumption from Childhood to Adulthood: The Cardiovascular Risk…
2019
A physically active lifestyle and a diet rich in vegetables and fruits have a central role in promoting health. This study examined the associations between leisure-time physical activity (LTPA) trajectories and fruit and vegetable consumption (FVC) from childhood to middle age. The data were drawn from the Cardiovascular Risk in Young Finns Study with six age cohorts. Participants were 9 to 18 years (n = 3536