This work focuses on the control of a camera mounted on a differential drive robot via a VPC (Visual Predictive Control) scheme. First, an exact model of the visual feature prediction is presented ...for this robotic system. Next, relying on the equivalent command vector concept, a parallel implementation on a GPU (Graphics Processing Unit) of the computation of the cost function and its gradient is presented. Finally, results show that the proposed approach is more accurate than the ones classically used and can be up to six times faster than CPU-based (Central Processing Unit) one for large prediction horizons and numerous visual features. It then becomes possible to implement a VPC controller running sufficiently fast to perform a navigation tasks, while guaranteeing the closed-loop stability by relying on large prediction horizons.
•An image processing to extract the flesh and the calyx from an image is proposed.•It relies on image color segmentation in a two dimensional color space.•Results are improved thanks to a blob ...detection and selection stage.•The algorithm is to tune and allows accurate extraction of the areas of interest.•It deals with natural variation in strawberry shape and visual appearance.
This paper presents an image processing algorithm that automatically extracts the flesh and calyx areas from strawberry images. Images are captured by a camera included in a strawberry de-capping machine. Lighting is controlled and the background is known, conditions that are typical of postharvest processing. The goal is to extract as many flesh and calyx pixels as possible while rejecting any pixels belonging to the background. The proposed approach relies on image color segmentation in a two-dimensional color space, followed by a blob detection and selection stage. A set of 250 images is used to analyze the sensitivity of the algorithm with respect to user-defined parameters, and evaluate the performance of the approach. The algorithm appears to be easy to tune and allows accurate extraction of the areas of interest despite natural variation in strawberry shape and visual appearance. More than 98% of the flesh area was successfully extracted by the algorithm with less than 1% of the background pixels falsely included. Moreover, up to 79% of the calyx area could be extracted with less than 0.25% erroneous background pixels. Finally, the algorithm has been implemented using the C++ and Cuda languages and can be executed in real-time.
In the literature devoted to them, the diagnosis of their "depoliticization" is dominant. Theories of international relations confined them to a "below" of politics. Under the heading of ...functionalism, David Mitrany proposed, in the mid-twentieth century, a vision still prevailing today.
The impacts of disaster events such as earthquakes on economic and human lives are increasing every year, in particular due to the growing urbanization. Until recently, stakeholders involved in ...disaster risk management focused their efforts mainly on the response phase, immediately after the crisis. Following the recommendations of several recent studies and in order to minimize the increasing impacts of natural disasters, decision-makers and major stakeholders have showed an increasing interest in mitigation activities. Earth Observation (EO) data from space could bring a significant added value to the various phases of the seismic risk management cycle from the mitigation and preparedness phases. Space agencies need to better contribute to the management of geohazards in response to the growing request from the community of users (e.g. seismologists, insurance companies, urban planners). To foster the use of EO remote sensing data, satellite data providers have to take the appropriate measures to remove the policy and technical barriers related to the data access. They have also to increase the awareness of the community of users on the potential benefits that could be gained from the use of EO satellite data. This paper will provide examples of areas where EO remote sensing data from space could bring an added value to the current management of risks and crisis related to earthquakes. Then, the paper will describe the strategic measures undertaken by the European Space Agency in an international framework, to foster the use of satellite data by the various relevant stakeholders.
Because of the pervasive influence of theories about the normative ‘devaluation of war’ and about the ‘preference’ of Europeans for ‘norms over force’, it is commonly assumed that Europeans have ...‘repudiated’ the use of force in international relations. However, European governments – especially France and the UK – have participated in a number of important military operations in the post-Cold War era, based on various justifications: sanctions against an aggressive state, protecting civilian populations from large scale crimes, fighting non-state radical armed groups. Most of these operations were multilateral in nature but France has also engaged in several national operations over the last years in Africa. The level of domestic support that these military interventions generally enjoy – as revealed by numerous surveys – indicates that Europeans do not systematically prefer ‘norms over force’ but still believe in just war norms.
The balance sheets of foreign policy heads of state are internationalists that elections are the specialists in electoral sociology: an exercise requires. The subject itself as an object of research, ...even in its thematic and chronological delimitations declinations. One can fear a result a priori waited long enough. The richness and diversity of the themes explored in this book devoted to the foreign policy of Jacques Chirac as well as the expertise of the authors mobilis's on each of the themes used to avoid overall it through. Once closed, the book gives the impression of diplomatic density at which the presidency Chirac, long twelve years (1995-2007) and marked by cohabitation with Jospin government has faced, both in Europe (wars in former Yugoslavia , treaties of Amsterdam and Nice, enlargement of the European Union, failure of the Constitutional Treaty) and internationally (September 11, 2001, wars in Afghanistan and Iraq). Adapted from the source document.
We address the problem of multi-sensor-based navigation in a cluttered environment for a non-holonomic robot. To perform such a successful and safe navigation, three controllers realizing, ...respectively, nominal vision-based navigation, obstacle bypassing and occlusion avoidance have
been designed using the task function approach. Then it suffices to sequence them to realize the complete mission. To guarantee the control continuity when switching between two successive controllers, two sequencing approaches have been used and compared. Simulation results validate our work.
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