650 research outputs found
Direct Visual Servoing Framework based on Optimal Control for Redundant Joint Structures
This paper presents a new framework based on optimal control to define new dynamic visual controllers to carry out the guidance of any serial link structure. The proposed general method employs optimal control to obtain the desired behaviour in the joint space based on an indicated cost function which determines how the control effort is distributed over the joints. The proposed approach allows the development of new direct visual controllers for any mechanical joint system with redundancy. Finally, authors show experimental results and verifications on a real robotic system for some derived controllers obtained from the control framework.This work was funded by the Spanish Ministry of Economy, the European FEDER funds and the Valencia Regional Government, through the research projects DPI2012-32390 and PROMETEO/2013/085
Control of Redundant Joint Structures Using Image Information During the Tracking of Non-Smooth Trajectories
Visual information is increasingly being used in a great number of applications in order to perform the guidance of joint structures. This paper proposes an image-based controller which allows the joint structure guidance when its number of degrees of freedom is greater than the required for the developed task. In this case, the controller solves the redundancy combining two different tasks: the primary task allows the correct guidance using image information, and the secondary task determines the most adequate joint structure posture solving the possible joint redundancy regarding the performed task in the image space. The method proposed to guide the joint structure also employs a smoothing Kalman filter not only to determine the moment when abrupt changes occur in the tracked trajectory, but also to estimate and compensate these changes using the proposed filter. Furthermore, a direct visual control approach is proposed which integrates the visual information provided by this smoothing Kalman filter. This last aspect permits the correct tracking when noisy measurements are obtained. All the contributions are integrated in an application which requires the tracking of the faces of Asperger children
Infant Responding to Joint Attention, Executive Processes, and Self-Regulation in Preschool Children
Infant joint attention is related to behavioral and social outcomes, as well as language in childhood. Recent research and theory suggests that the relations between joint attention and social–behavioral outcomes may reflect the role of executive self-regulatory processes in the development of joint attention. To test this hypothesis two studies were conducted. The first, cross-sectional study examined the development of responding to joint attention (RJA) skill in terms of increasing executive efficiency of responding between 9 and 18 months of age. The results indicated that development of RJA was characterized by a decreased latency to shift attention in following another person\u27s gaze and head turn, as well as an increase in the proportion of correct RJA responses exhibited by older infants. The second study examined the longitudinal relations between 12-month measures of responding to joint attention and 36-month attention regulation in a delay of gratification task. The results indicated that responding to joint attention at 12-months was significantly related to children\u27s use of three types of self-regulation behaviors while waiting for a snack reward at 36 months of age. These observations are discussed in light of a developmental theory of attention regulation and joint attention in infancy
Is the vessel fishing? Discrimination of fishing activity with low-cost intelligent mobile devices through traditional and heuristic approaches
Knowing the activity of fishing vessels accurately and in real time means a leap in quality in the management of fishing activity. This paper presents the development of a new fishing activity monitoring integral system (FAMIS) that can complement and overcome the limitations of current fishing vessel monitoring systems (VMS). FAMIS is developed on the basis of a low-cost mobile device with GPS sensors, accelerometer, gyroscope and magnetic field and integrates different statistical methods (discriminant functions) and heuristics (artificial neural networks and vectorial support machines) as techniques to classify the information recorded by the sensors of a mobile device during fishing activity. The results obtained with FAMIS indicate that, in general, heuristics have a high degree of discrimination of each of the phases of fishing operation and that, in particular, multilayer perceptrons (MLPs) are capable of correctly identifying 96.3% of towing phases using only GPS and gyro sensors
Dynamic visual servo control of a 4-axis joint tool to track image trajectories during machining complex shapes
A large part of the new generation of computer numerical control systems has adopted an architecture based on robotic systems. This architecture improves the implementation of many manufacturing processes in terms of flexibility, efficiency, accuracy and velocity. This paper presents a 4-axis robot tool based on a joint structure whose primary use is to perform complex machining shapes in some non-contact processes. A new dynamic visual controller is proposed in order to control the 4-axis joint structure, where image information is used in the control loop to guide the robot tool in the machining task. In addition, this controller eliminates the chaotic joint behavior which appears during tracking of the quasi-repetitive trajectories required in machining processes. Moreover, this robot tool can be coupled to a manipulator robot in order to form a multi-robot platform for complex manufacturing tasks. Therefore, the robot tool could perform a machining task using a piece grasped from the workspace by a manipulator robot. This manipulator robot could be guided by using visual information given by the robot tool, thereby obtaining an intelligent multi-robot platform controlled by only one camera.This work was funded by the Ministry of Science and Innovation of Spain Government through the research project DPI2011-22766 and DPI2012-32390
First approach to automatic performance status evaluation and physical activity recognition in cancer patients
The evaluation of cancer patients’ recovery is still under the big subjectivity of physicians. Many different systems have been successfully implemented for physical activity evaluation, nonetheless there is still a big leap into Performance Status evaluation with ECOG and Karnofsky’s Performance Status scores. An automatic system for data recovering based on Android smartphone and wearables has been developed. A gamification implementation has been designed for increasing patients’ motivation in their recovery. Furthermore, novel and without-precedent algorithms for Performance Status (PS) and Physical Activity (PA) assessment have been developed to help oncologists in their diagnoses
Lung tumorspheres as a drug screening platform against cancer stem cells
Treatment resistance and metastasis are linked to cancer stem cells (CSCs). This population represents a promising target, but remains unexplored in lung cancer. The main objective of this study was to characterize lung CSCs and discover new therapeutic strategies
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