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(IAI) Artículos post-print
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Walking machines - initial testbeds, first industrial applications and new research - González de Santos, Pablo; Armada, Manuel; Jiménez, María Antonia
Walking locomotion theory has been drastically improved during the last decade and now the technology seems to be ready for industrial applications. More than 60 different climbing and walking machines developed in research laboratories and universities have been catalogued, but industrial applications are emerging very slowly. This article covers some of the activity and production run at the Institute for Industrial Automation (CSIC) related to development of prototypes for both research purposes and industrial applications as well.
Development of walking machines at IAI-CSIC - González de Santos, Pablo; Armada, Manuel; Jiménez, María Antonia
Describes 2 walking robots developed at CSIC, Madrid: RIMHO, an experimental quadruped robot with insect-like legs; and ROWER, a ship-building robot consisting of the robot body surrounded by 4 legs which each grip rigid bars both below and above the body. Also discusses SILO, a project considering outstanding problems in walking robots.
High-Resolution Indirect Feet–Ground Interaction Measurement for Hydraulic-Legged Robots - Nabulsi, Samir; Sarriá, Javier F.; Montes, Héctor; Armada, Manuel
Abstract: Feet–ground interactions influence the legged robot’s
stability. In this paper, a high-resolution indirect force measurement
for hydraulic-legged robots is presented. The use of pressure
transducers placed at one or both chambers of the robot’s
double-effect hydraulic actuators is investigated, and conclusions
are drawn regarding their capability for indirectly measuring
the contact forces between the feet and the ground. Because of
the nonlinear dynamic properties of hydraulic cylinders, friction
modeling is essential to determine at all times the true forces of
each foot against the soil. The test case is called ROBOCLIMBER,
which is a bulky quadruped climbing and walking machine able
to carry heavy-duty drilling equipment for landslide consolidation
On finding the relevant dynamics for model based controlling walking robots - García, Elena; Gálvez, J. A; González de Santos, Pablo
Leg dynamics are often ignored in the real-time control of walking
robots because of the high gearing used in leg transmissions. However, the use of a
gear reduction high enough to discount Coriolis and centripetal components yields
additional non-desired dynamics, which are friction, backlash and elasticity. In such
cases, simplifying robot dynamics without considering the effect of gear dynamics
leads to unavoidable errors. In order to make dynamic equations reflect the reality
of the physical system, it is of paramount importance to model the most significant
effects acting on the system. Robot dynamics could then be analyzed and related
to trajectory parameters for motion-control purposes. In this paper,...
A Computational Method to Calculate the Longitudinal Wave Evolution Caused by Interfaces Between Isotropic Media - Buiochi, Flávio; Martínez, Óscar; Ullate, Luis G.; Montero de Espinosa, Francisco
This paper presents a computational method to calculate the reﬂected and transmitted ultrasonic ﬁelds at interfaces of complex geometry. The method is performed in two steps. As ﬁrst step, the velocity potential impulse response from an arbitrary aperture is determined at the interface using the Rayleigh integral and considering the reﬂection and transmission coeﬃcients. In a second step, the simulated ﬁelds are calculated by applying the Rayleigh-Sommerfeld integral to the whole, extended interface. In order to validate the method, some experimental cases as, for instance, plane and cylindrical concave surfaces between two media (water-acrylic) were tested. The experimental ultrasonic ﬁelds...
A Comparative Study of Stability Margins for Walking Machines - García, Elena; Estremera, Joaquín; González de Santos, Pablo
Several static and dynamic stability criteria have been defined in the course of walking robot history. Nevertheless, different applications may require different criteria and, to the authors' best knowledge, there is no qualitative classification of such stability measurements. Using the wring stability criterion to control a robot gait may prevent the task from succeeding. Furthermore, if the optimum criterion is found, the robot gait can also be optimized. In this paper, the stability criteria that have been applied to walking robots with at least four legs are examined in terms of their stability margins in different static and dynamic situations....
The Progressive Focusing Correction Technique for Ultrasound Beamforming - Fritsch Yusta, Carlos; Parrilla Romero, Montserrat; Ibáñez Rodríguez, Alberto; Giacchetta, Roberto Carlos; Martínez Graullera, Óscar
This work presents a novel method for digital ultrasound beamforming based on programmable table look-ups, in which vectors containing coded focusing information are eﬃciently stored, achieving an information density of a fraction of bit per acquired sample. Timing errors at the foci are within half the period of a master clock of arbitrarily high frequency to improve imaging quality with low resource requirements. The technique is applicable with conventional as well as with ∆Σ converters.
The bit-width of the focusing code and the number of samples per focus can be deﬁned to improve both memory size and F# with controlled...
Beam Steering with Segmented Annular Arrays - Ullate, Luis G.; Godoy, Gregorio; Martínez, Óscar; Sánchez, Teresa
Two-dimensional (2-D) arrays of squared matrix have maximum periodicity in their main directions; consequently, they require half wavelength (λ/2), interelement spacing to avoid grating lobes. This condition gives rise to well-known problems derived from the huge number of array elements and from their small size. In contrast, 2-D arrays with curvilinear conﬁguration produce lower grating lobes and, therefore, allow the element size to be increased beyond λ/2. Using larger elements, these arrays have the advantage of reducing the number of elements and of increasing the signal-to-noise ratio (SNR).
In this paper, the beamforming properties of segmented annular phased arrays are...
An Improved Energy Stability Margin for An Improved Energy Stability Margin for - García, Elena; González de Santos, Pablo
Several static and dynamic stability criteria have been defined
in the course of walking-robot history. Nevertheless, previous work
on the classification of stability criteria for statically stable walking
machines (having at least four legs) reveals that there is no stability
margin that accurately predicts robot stability when inertial and
manipulation effects are significant. In such cases, every momentum-
based stability margin fails. The use of an improper stability criterion
yields unavoidable errors in the control of walking robots. Moreover,
inertial and manipulation effects usually appear in the motion of these
robots when they are used for services or industrial applications.
A new stability margin that accurately measures robot stability
Using Soft Computing Techniques for Improving Foot Trajectories in Walking Machines - García, Elena; González de Santos, Pablo
Walking machines have been investigated during the last 40 years and some basic
techniques of this field are already well known. However, some aspects still need
to be optimized. For instance, speed seems to be one of the major shortcomings of
legged robots; thus, improving leg speed has been chosen as the main aim of this
work. Although some algorithms for optimizing trajectory control of robot manipulators
already exist, we propose a more computationally efficient method that employs
fuzzy set theory to involve real dynamic effects over leg motion instead of an inaccurate
mathematical model. In this article, we improve leg speed by automatically tuning
the acceleration of...
Dealing with internal and external perturbations on walking - García, Elena; González de Santos, Pablo; Matia, F
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 gaitadaptation
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 maximize robot stability. The adaptation method
is inspired in the natural gait adaptation...
On the Improvement of Walking Performance in Natural Environments by a Compliant Adaptive Gait - García, Elena; González de Santos, Pablo
It is a widespread idea that animal-legged locomotion
is better than wheeled locomotion on natural rough terrain.
However, the use of legs as a locomotion system for vehicles and
robots still has a long way to go before it can compete with wheels
and trucks, even on natural ground. This paper aims to solve
two main disadvantages plaguing walking robots: their inability
to react to external disturbances (which is also a drawback of
wheeled robots); and their extreme slowness. Both problems
are reduced here by combining: 1) a gait-parameter-adaptation
method that maximizes a dynamic energy stability margin and 2)
an active-compliance controller with a new term that compensates
for stability variations,...
Velocity Dependence in the Cyclic Friction Arising with Gears - García, Elena; González de Santos, Pablo; Canudas de Wit, Carlos
Recent research on friction in robot joints and transmission systems
has considered meshing friction a position-dependent friction component.
However, in this paper we show experimental evidence that
meshing friction depends highly on joint speed.We identify the meshing
friction in the gearboxes of a robotic leg, and we propose a new
mathematical model that considers the rate dependency of meshing
friction. The resulting model is validated through experimentation.
Results show that meshing friction is responsible for friction torque
oscillations with an amplitude up to 25 percent of the average friction
torque at low speeds. Therefore, this friction component should
be taken into account if an accurate friction model is desired.
Using Fuzzy Logic in Automated Vehicle Control - Naranjo, José E.; González, Carlos; García, Ricardo; Pedro, Teresa de; Sotelo, Miguel A.
of a mass-produced
vehicle use fuzzy logic
techniques to both
into the vehicle control
Comparative study of chained systems theory and fuzzy logic as a solution for the nonlinear lateral control of a road vehicle - Sotelo, Miguel Angel; Naranjo, Eugenio; García, Ricardo; Pedro, Teresa de; González, Carlos
This paper presents a comparative study of
different lateral controllers applied to the autonomous
steering of automobiles. The nonlinear nature of vehicle
dynamics makes it a challenging problem in
the Intelligent Transportation Systems (ITS) field, as
long as a stable, accurate controller is compulsorily
needed in order to ensure safety during navigation.
The problem has been tackled under two different approaches.
The first one is based on chained systems theory,
while the second controller relies on fuzzy logic.
A comparative analysis has been carried out based
on the results achieved in practical trials. Real tests
were conducted using a DGPS-driven electric Citroen
Berlingo in a private test circuit located at the Industrial
Lane-Change Fuzzy Control in Autonomous Vehicles for the Overtaking Maneuver - Naranjo, José E.; Gonzalez, Carlos; García, Ricardo; Pedro, Teresa de
Abstract—The automation of the overtaking maneuver is considered
to be one of the toughest challenges in the development
of autonomous vehicles. This operation involves two vehicles (the
overtaking and the overtaken) cooperatively driving, as well as
the surveillance of any other vehicles that are involved in the
maneuver. This operation consists of two lane changes—one from
the right to the left lane of the road, and the other is to return
to the right lane after passing. Lane-change maneuvers have been
used to move into or out of a circulation lane or platoon; however,
overtaking operations have not received much coverage in the
literature. In this paper, we present an...
Distributed production system : a framework to solve the printed circuit board routing - Pedro, Teresa de; Ribeiro, A.; Pedraza, José Luis
Production systems (PSs), based on a very general idea (condition-action pairs),
are widely used in artificial intelligence for modeling intelligcnt behavior and
building expert systems. However, PS programs are very computation-intensive
and ron quite slowly. This precludes the use of PSs in many domains that require
real-time response and high performance. Our approach for speeding up the
execution of PSs is to design special message-handling machines, with architectures
matched with the characteristics of the algorithms. In this line, a model that
allows one to describe a PS as a set of concurrent processes, operating in a
cooperative way and communicating through channels, is developed. To prove its
A vision-based method for weeks identification through the Bayesian decision theory - Tellaeche, A.; Burgos Artizzu, Xavier P.; Pajares, G.; Ribeiro, A.
One of the objectives of precision agriculture is to minimize the volume of herbicides that are applied to the fields through the use of
site-specific weed management systems. This paper outlines an automatic computer vision-based approach for the detection and differential
spraying of weeds in corn crops. The method is designed for post-emergence herbicide applications where weeds and corn plants display
similar spectral signatures and the weeds appear irregularly distributed within the crop’s field. The proposed strategy involves two processes:
image segmentation and decision making. Image segmentation combines basic suitable image processing techniques in order to extract cells
from the image as the low...
A new vision-based approach to differential spraying in precision agriculture - Tellaeche, A.; Burgos Artizzu, Xavier. P.; Pajares, G.; Ribeiro, A.; Fernández-Quintanilla, C.
A b s t r a c t :
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