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(IAI) Artículos post-print
Mostrando recursos 1 - 20 de 67
Tibialis Anterior muscle coherence during controlled voluntary activation in patients with spinal cord injury: diagnostic potential for muscle strength, gait and spasticity - Bravo-Esteban, Elisabeth; Taylor, Julian; Aleixandre, Manuel; Simon-Martínez, Cristina; Torricelli, Diego; Pons, José L; Gómez-Soriano, Julio
Abstract Background Coherence estimation has been used as an indirect measure of voluntary neurocontrol of residual motor activity following spinal cord injury (SCI). Here intramuscular Tibialis Anterior (TA) coherence estimation was performed within specific frequency bands for the 10-60 Hz bandwidth during controlled ankle dorsiflexion in subjects with incomplete SCI with and without spasticity. Methods In the first cohort study 15 non-injured and 14 motor incomplete SCI subjects were recruited to evaluate TA coherence during controlled movement. Specifically 15-30 Hz EMG was recorded during dorsiflexion with: i) isometric activation at 50, 75 and 100% of maximal voluntary torque (MVT), ii)...
Computer vision system for estimating and controlling the weight of glass gobs during their industrial formation process - Jiménez, Antonio R.; Laizola Loinaz, Eskarne; Morgado Rodríguez, Fernando; Calvache Sánchez, Mar; Seco, Fernando
We present a computer vision system for measuring the weight of gobs during a glass-forming process, and a control strategy to automatically correct any weight deviation from a given set point. The system is based on a reliable gob area estimation using image-processing algorithms. A monochrome CCD high-resolution camera and a photodetector for synchronizing acquisition are used for registering gob images. Assuming that the gob has symmetry of revolution about the vertical axis, the proposed system estimates the weight of gobs with accuracy better than ±0.75%. A learning weight control strategy is proposed based on a proportional-integral (PI)-repetitive control scheme....
Thrust control, stabilization and energetics of a quadruped running robot - Estremera, Joaquín; Waldron, K.J.
In order to achieve powered autonomous running robots it is essential to develop efficient actuator systems, especially for generating the radial thrust in the legs. In addition, the control of the radial thrust of the legs can be a simple, effective method for stabilizing the body pitch in a running gait. This paper presents the mechanical systems, models and control strategies employed to generate and control leg thrust in the KOLT quadruped running robot. An analytical model of the electro-pneumatic leg thrusting system is presented and analyzed to evaluate its performance and to facilitate the design of control strategies. Several...
Analysing and solving body misplacement problems in walking robots with round rigid feet - Guardabrazo, T.; Jiménez, María Antonia; González de Santos, Pablo
Round rigid feet for multi-legged robots offer a number of advantages over flat feet, and even over flat feet with articulated ankles. The main benefits are low cost, low complexity and robustness. A round rigid foot of small radius works well on hard terrain; however, it is prone to sink into soft terrain. Sinking can be avoided by increasing the radius of the foot, but in that case a round foot will roll during the leg-support phase, causing the hip to become misplaced and the robot to assume an incorrect attitude. This paper analyses this problem and provides a hip-control...
Methodology for zero-moment point experimental modeling in the frequency domain - Caballero, R.; Armada, Manuel; Alarcón, Pedro
Frequency domain methodology is applied to obtain a nominal model for the Zero-Moment Point (ZMP) stability index of a biped robot in an attempt to establish a relationship between the robot trunk trajectories and the stability margin of the contact surface of the foot (or feet) touching the supporting soil. To this end the biped robot trunk is excited with a variable frequency sinusoidal signal around several operating points. These input oscillations generate other output oscillations that can be analyzed with the help of the ZMP measurement system. The proposed ZMP modeling approach not only considers classical rigid body model...
Reliable, built-in, high-accuracy force sensing for legged robots - Montes, Héctor; Nabulsi, Samir; Armada, Manuel
An approach for achieving reliable, built-in, high-accuracy force sensing for legged robots is presented, based on direct exploitation of the properties of a robot's mechanical structure. The proposed methodology relies on taking account of force-sensing requirements at the robot design stage, with a view to embedding force-sensing capability within the mechanical structure of the robot itself. The test case is ROBOCLIMBER, a bulky, quadruped climbing and walking machine whose weighty legs enable it to carry out heavy-duty drilling operations. The paper shows that, with finite-element analysis of ROBOCLIMBER's mechanical configuration during the design stage, candidate positions can be selected for...
Dealing with internal and external perturbations on walking robots - García Armada, Elena; González de Santos, Pablo; Matía, Fernando
Up to now, walking robots have been working outdoors under favorable conditions and using very large stability margins to cope with natural environments and intrinsic robot dynamics that can cause instability in these machines when they use statically-stable gaits. The result has been very slow robots prone to tumble down in the presence of perturbations. This paper proposes a novel gait-adaptation method based on the maximization of the Normalized Dynamic Energy Stability Margin. This method enables walking-machine gaits to adapt to internal (robot dynamics) and external (environmental) perturbations, including the slope of the terrain, by finding the gait parameters that...
Location of legged robots in outdoor environments - Cobano, José A.; Estremera, Joaquín; González de Santos, Pablo
Knowledge of a robot's position with an accuracy of within a few centimeters is required for potential applications for legged robots, such as humanitarian de-mining tasks. Individual sensors are unable to provide such accuracy. Thus information from various sources must be used to accomplish the tasks. Following this trend, this paper describes the method developed for estimating the position of legged robots in outdoor environments. The proposed method factors in the specific features of legged robots and combines dead-reckoning estimation with data provided by a Differential Global Positioning System through an extended Kalman filter algorithm. This localization system permits accurate...
Service Robots - Aracil, Rafael; Armada, Manuel; Balaguer, Carlos
[EN]The term Service Robots appears at the end of 80s as the necessity of development machines and equipments able to work in environments different to manufacturing. Service Robots must be work in non structural environments, in changing ambient conditions and with close interaction with humans. The IEEE Robotics and Automation Society created in 1995 the Technical Committee on Service Robots which defined in 2000 the fields of applications of Service Robots which can be divided in two big groups: 1) non manufacturing production sectors such as construction, agriculture, ship making, mining, medicine, etc. and 2) service sector itself: assistance and...
A scanning robotic system for humanitarian de-mining activities - Ponticelli, Roberto; García Armada, Elena; González de Santos, Pablo; Armada, Manuel
[Purpose]Humanitarian de-mining tasks require the use of specific detecting sets to detect landmines. These sets are normally based on a one-point sensor, which must be moved over the infested terrain by a combination of a scanning manipulator and a mobile platform. The purpose of this paper is to present the development of the sensor head and the scanning manipulator.
Power assist devices for installing plaster panels in construction - González de Santos, Pablo; Estremera, Joaquín; García Armada, Elena; Armada, Manuel
Building construction is a very interesting field for automation, but the incorporation of fully automated systems is a very slow matter because of the inherent difficulties of its unstructured and changing environment. However, this industry produces a large number of accidents and injuries in workers and government agencies are demanding protection for them. An intermediate solution is to provide the workers with new tools capable of supplying power to carry the heavy loads while the workers are still providing their sensor system and intelligence. This is just the concept of a power assist device. This paper presents two versions of...
Motor modules in robot-aided walking - Gizzi, Leonardo; Nielsen, Jørgen F; Felici, Francesco; Moreno, Juan C.; Pons, José L; Farina, Dario
Abstract Background It is hypothesized that locomotion is achieved by means of rhythm generating networks (central pattern generators) and muscle activation generating networks. This modular organization can be partly identified from the analysis of the muscular activity by means of factorization algorithms. The activity of rhythm generating networks is described by activation signals whilst the muscle intervention generating network is represented by motor modules (muscle synergies). In this study, we extend the analysis of modular organization of walking to the case of robot-aided locomotion, at varying speed and body weight support level. Methods Non Negative Matrix Factorization was applied on...
A new vision-based approach to differential spraying in precision agriculture - Tellaeche, A.; Burgos Artizzu, Xavier P.; Pajares, G.; Ribeiro Seijas, A.; Fernández Quintanilla, César
One of the objectives of precision agriculture is to minimize the volume of herbicides by
using site-specific weed management systems. To reach this goal, two major factors need
to be considered: (1) the similarity of spectral signatures, shapes, and textures between
weeds and crops and (2) irregular distribution of weeds within the crop. This paper outlines
an automatic computer vision method for detecting Avena sterilis, a noxious weed growing
in cereal crops, and differential spraying to control the weed. The proposed method
determines the quantity and distribution of weeds in the crop fields and applies a decisionmaking
strategy for selective spraying, which forms the main focus of...
Biologically based design of an actuator system for a knee–ankle–foot orthosis - Cullell, A.; Moreno, Juan C.; Rocon, Eduardo; Forner-Cordero, A.; Pons Rovira, José Luis
Knee–ankle–foot orthosis are systems used to restore human gait, providing stability during
stance phase. A concept of actuator for knee–ankle–foot orthosis was developed based
on biomechanical data. The actuator is conceived to provide mechanical means to reproduce
the normal kinematics during human gait at joint level. Behaviour of the joints of
the lower limb was approximated by elastic means and an actuator for each joint was
designed and constructed. The rationale of the design process is presented, considering
the functional aspects and aiming at a lightweight solution with low power demand. Tests
performed with one patient suffering from post-poliomyelitis syndrome are presented and
evidence of functional compensation during...
Improving weed pressure assessment using digital images from an experience-based reasoning approach - Burgos Artizzu, Xavier P.; Ribeiro Seijas, A.; Tellaeche, A.; Pajares, G.; Fernández Quintanilla, César
One of the main goals of Precision Agriculture is site-specific crop management to reduce
the production of herbicide residues. This paper presents a computer-based image analysis
system allowing users to input digital images of a crop field, and to process these by a
series of methods to enable the percentages of weeds, crop and soil present in the image
to be estimated. The system includes a Case-Based Reasoning (CBR) system that, automatically
and in real time, determines which processing method is the best for each image. The
main challenge in terms of image analysis is achieving appropriate discrimination between
weeds, crop and soil in outdoor field images...
A new manipulator structure for power-assist devices - González de Santos, Pablo; García Armada, Elena; Sarria, Javier F.; Ponticelli, Roberto; Reviejo, Jesús
Purpose – This paper introduces a new manipulator structure to configure power-assist
devices in order to protect operators from musculoskeletal disorders. The
mechanical structure and the control system are presented, along with their main
Design/methodology/approach – The new structure is designed under the criterion of
minimizing the torques required for handling payloads of up to 75 kg in an
easily controlled system.
Findings – A new structure is provided, based on electrical AC motors and capable of
handling high payloads yet exerting low motor torque.
Originality/value – The application of the criterion of minimizing the required torques
to handle he