Jordi Palacín

Universitat de Lleida, Lérida, Catalonia, Spain

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Publications (72)68.08 Total impact

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    ABSTRACT: This paper presents the measurement of gas concentration and wind intensity performed with a mobile robot in a custom turbulent wind tunnel designed for experimentation with customizable wind and gas leak sources. This paper presents the representation in different information layers of the measurements obtained in the turbulent wind tunnel under different controlled environmental conditions in order to describe the plume of the gas and wind intensities inside the experimentation chamber. The information layers have been generated from the measurements gathered by individual onboard gas and wind sensors carried out by an autonomous mobile robot. On the one hand, the assumption was that the size and cost of these specialized sensors do not allow the creation of a net of sensors or other measurement alternatives based on the simultaneous use of several sensors, and on the other hand, the assumption is that the information layers created will have application on the development and test of automatic gas source location procedures based on reactive or nonreactive algorithms.
    Preview · Article · Jan 2016 · Journal of Sensors
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    ABSTRACT: This paper presents the implementation of a soccer mobile robot agent that uses vision based object detection procedures. The soccer mobile robot is based on a Google Android smartphone and takes advantage of its computation and sensing capabilities. The agent implementation uses a multithreading methodology to generate different agent processes such as the vision sense, the decisionmaking, and the application manager. The vision sense thread captures images from the smartphone camera and provides environment information using Renderscript computation while the decision-making thread provides effective soccer agent behavior. This paper presents and discusses the agent implementation and the effectiveness of the vision based object detection procedures.
    No preview · Article · Aug 2015
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    ABSTRACT: This paper presents a method for vineyard yield estimation based on the analysis of high-resolution images obtained with artificial illumination at night. First, this paper assesses different pixel-based segmentation methods in order to detect reddish grapes: threshold based, Mahalanobis distance, Bayesian classifier, linear color model segmentation and histogram segmentation, in order to obtain the best estimation of the area of the clusters of grapes in this illumination conditions. The color spaces tested were the original RGB and the Hue-Saturation-Value (HSV). The best segmentation method in the case of a non-occluded reddish table-grape variety was the threshold segmentation applied to the H layer, with an estimation error in the area of 13.55%, improved up to 10.01% by morphological filtering. Secondly, after segmentation, two procedures for yield estimation based on a previous calibration procedure have been proposed: (1) the number of pixels corresponding to a cluster of grapes is computed and converted directly into a yield estimate; and (2) the area of a cluster of grapes is converted into a volume by means of a solid of revolution, and this volume is converted into a yield estimate; the yield errors obtained were 16% and −17%, respectively.
    Preview · Article · Apr 2015 · Sensors
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    ABSTRACT: This paper presents the preliminary results obtained when using a mobile robot to measure gas and wind intensity in an indoor area by means of several attached sensors such as a LIDAR, an e-nose, and an anemometer. The robot navigation was performed by means of a random path planning and the robot self location was performed by means of an SLAM procedure. This paper presents the first preliminary results obtained in a set of measurement experiments. In all cases, the indoor area has a fixed artificial simulated airflow and an induced gas leak source placed in different locations of the experimentation area. Results have shown different gas diffusion profiles in the different experiments performed.
    No preview · Article · Jan 2015
  • E. Clotet · D. Martínez · J. Moreno · M. Tresanchez · J. Palacín
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    ABSTRACT: This paper presents the development of an Assistant Personal Robotic (APR) designed with the objective of creating a high reliable robot that can be used in several home applications such as: home safety, elder people supervision and remote assistance, remote presence, etc. In this proposal the APR is remotely controlled by a smartphone or portable tablet with Wi-Fi connectivity. The APR design has taken into consideration safety factors, mobility and physical restrictions of an average home; including opened doors, tight turns, and narrow corridors. The APR design includes several onboard sensors in order to protect the robot and avoid collisions with fixed or moving surrounding objects.
    No preview · Article · Jan 2015
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    ABSTRACT: This paper presents the experimental application of an autonomous mobile robot for gas leak detection in indoor environments. The application is focused to automatize a human-risky operation in indoor areas. The goal of the autonomous mobile robot is the localization of a toxic gas leak source. So, the mobile robot has to explore the whole area and perform an auto-localization procedure based on a SLAM method and a LIDAR sensor. The mobile robot measures gas concentration by using a photoionization detector. The experimentation was realized in a large indoor environment in a university facility with a simulated gas leak source. The combination of the results from the auto-localization procedure with the information of the sensors allows the estimation of the gas leak source location.
    No preview · Article · Oct 2014
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    ABSTRACT: This paper proposes the assessment of different methods designed for time domain detection of pure vowel sounds in order to develop future devices with simplified computer interaction focused on people with physical disabilities. The time domain detection method is based on filter the sound, detect periodic information and then compute the average periodic amplitude of the filtered and non-filtered signals. This detection method has been applied to pure Spanish vowels which have a similar pronunciation in different languages. The periodic information of the different vowels has been stored in reference databases in order to assess the different time domain detection methods proposed. The best detection results obtained showed a 100% detection success for the /a/, /e/, /i/ and /o/ phonemes and a 90% detection success for the /u/ phoneme when using the periodic time domain description of the signals.
    No preview · Article · Oct 2014
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    ABSTRACT: This paper presents an automatic method for counting red grapes from high-resolution images of vineyards taken under artificial lighting at night. The proposed method is based on detecting the specular reflection peaks from the spherical surface of the grapes. These intensity peaks are detected by means of a morphological peak detector based on the definition of one central point and several radial points. The morphological condition applied is that the intensity of the central point must be higher than all the radial points. The grape counting results obtained in different occlusion conditions were compared with a manual labeling procedure. On average, the percentage of extremely occluded grapes (occlusion higher than 75%) in the clusters was 33%, whereas the average counting detection error obtained with the automatic method proposed was −14% with only 7% of false positives, confirming that this proposal can count even highly occluded grapes.
    No preview · Article · Oct 2014 · Computers and Electronics in Agriculture
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    ABSTRACT: This paper proposes the development of an automatic fruit harvesting system by combining a low cost stereovision camera and a robotic arm placed in the gripper tool. The stereovision camera is used to estimate the size, distance and position of the fruits whereas the robotic arm is used to mechanically pickup the fruits. The low cost stereovision system has been tested in laboratory conditions with a reference small object, an apple and a pear at 10 different intermediate distances from the camera. The average distance error was from 4% to 5%, and the average diameter error was up to 30% in the case of a small object and in a range from 2% to 6% in the case of a pear and an apple. The stereovision system has been attached to the gripper tool in order to obtain relative distance, orientation and size of the fruit. The harvesting stage requires the initial fruit location, the computation of the inverse kinematics of the robotic arm in order to place the gripper tool in front of the fruit, and a final pickup approach by iteratively adjusting the vertical and horizontal position of the gripper tool in a closed visual loop. The complete system has been tested in controlled laboratory conditions with uniform illumination applied to the fruits. As a future work, this system will be tested and improved in conventional outdoor farming conditions.
    Preview · Article · Jul 2014 · Sensors
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    ABSTRACT: The use of an autonomous mobile robot to locate gas-leaks and air quality monitoring in indoor environments are promising tasks that will avoid risky human operations. However, these are challenging tasks due to the chaotic gas profile propagation originated by uncontrolled air flows. This paper proposes the localization of an acetone gas-leak in a 44 m-length indoor corridor with a mobile robot equipped with a PID sensor. This paper assesses the influence of the mobile robot velocity and the relative height of the PID sensor in the profile of the measurements. The results show weak influence of the robot velocity and strong influence of the relative height of the PID sensor. An estimate of the gas-leak location is also performed by computing the center of mass of the highest gas concentrations.
    Full-text · Article · Jun 2014 · Sensor Letters
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    ABSTRACT: This paper proposes the use of an autonomous assistant mobile robot in order to monitor the environmental conditions of a large indoor area and develop an ambient intelligence application. The mobile robot uses single high performance embedded sensors in order to collect and geo-reference environmental information such as ambient temperature, air velocity and orientation and gas concentration. The data collected with the assistant mobile robot is analyzed in order to detect unusual measurements or discrepancies and develop focused corrective ambient actions. This paper shows an example of the measurements performed in a research facility which have enabled the detection and location of an uncomfortable temperature profile inside an office of the research facility. The ambient intelligent application has been developed by performing some localized ambient measurements that have been analyzed in order to propose some ambient actuations to correct the uncomfortable temperature profile.
    Full-text · Article · Apr 2014 · Sensors
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    ABSTRACT: This paper presents an image processing method for in-line automatic and individual nectarine variety verification in a fruit-packing line based on the use of feature histogram vectors obtained by concatenating the histograms computed from different color layers of a circular central area of the skin of the nectarines processed. The verification procedure requires the definition of a small dataset with the feature histogram vectors corresponding to some reference nectarines (manually selected) whose skin clearly identifies the variety being processed. The in-line variety verification of each nectarine processed is then done by computing and comparing its current feature histogram vector with the reference dataset. This paper compares experimentally different alternatives for computing the feature histogram vectors and two methods for feature comparison and variety verification. The experimental validation consists of the automatic in-line processing of nectarine samples from different mixed varieties. The results show an 86% success rate in the case of an expert human operator and 100% when using feature histogram vectors computed in the Rg (red and gray) or YR‾ (luminance and normalized red) intensity color layers and when using correlation to compare the feature vectors.
    No preview · Article · Mar 2014 · Computers and Electronics in Agriculture
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    ABSTRACT: This paper presents an autonomous agent for gas leak source detection. The main objective of the robot is to estimate the localization of the gas leak source in an indoor environment without any human intervention. The agent implements an SLAM procedure to scan and map the indoor area. The mobile robot samples gas concentrations with a gas and a wind sensor in order to estimate the source of the gas leak. The mobile robot agent will use the information obtained from the onboard sensors in order to define an efficient scanning path. This paper describes the measurement results obtained in a long corridor with a gas leak source placed close to a wall.
    No preview · Article · Jan 2014
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    ABSTRACT: This paper presents an outdoor mobile robotic companion that is guided by GPS. The robotic companion is a wheeled mobile robot that uses a Google Android smartphone as a central processing unit. The mobile robot takes advantage of the integrated smartphone features such as wireless connectivity, USB interface for external electronic boards, and the GPS sensor. Moreover, the mobile robot companion can be controlled by another smartphone in order to define companion behaviors such as "go to location", "follow me", and "keep close" all of them based on the use of GPS information. The mobile robot has been tested as in long walks in order to evaluate the effectiveness of the artificial companion effect.
    No preview · Article · Jan 2014
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    ABSTRACT: This paper proposes a combined approach to the problem of opening a door with a mobile robot. In one hand, the detection of the doors and the doors handles is performed by means of a dedicated onboard camera. In the other hand, the mechanical interaction with the door handle is performed by means of a DC motor. Both devices have been designed in order to be included in the design of an assistive mobile robot. This combined proposal has been tested in a university facility where the contrast between the texture colors used in the structural elements has simplified the implementation of the visual detection procedures.
    No preview · Article · Jan 2014
  • M. Tresanchez · T. Palleja · M. Teixido · J. Palacin

    No preview · Article · Feb 2013
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    ABSTRACT: This paper presents the evaluation of the image segmentation capabilities of a mobile robot agent based on a Google Android Smartphone. The mobile agent was designed to operate autonomously in an environment inspired in a soccer game. The pixel-based color image segmentation capabilities was performed by testing different two-dimensional look up tables created from twodimensional color histograms of the objects appearing in the scenario. The best segmentation alternative was obtained when using of a two-dimensional look up table based on the H (hue) and V (value) color image description. The final conclusion is that a Google Android Smartphone has enough potential to define an autonomous mobile robot agent and play a game that requires color-based image segmentation capabilities.
    No preview · Article · Jan 2013
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    ABSTRACT: This paper proposes a practical methodology to implement a mobile robot agent based on a Google Android Smartphone. The main computational unit of the robot agent is a Smartphone connected through USB to a control motor board that drives two motors and one stick. The agent program structure is implemented using multi-threading methods with shared memory instances. The agent uses the Smartphone camera to obtain images and to apply image processing algorithms in order to obtain profitable information of its environment. Moreover, the robot can use the sensors embedded in the Smartphone to gather more information of the environment. This paper describes the methodology used and the advantages of developing a robot agent based on a Smartphone.
    No preview · Chapter · Jan 2013
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    ABSTRACT: This paper presents the use of an external fixed two-dimensional laser scanner to detect cylindrical targets attached to moving devices, such as a mobile robot. This proposal is based on the detection of circular markers in the raw data provided by the laser scanner by applying an algorithm for outlier avoidance and a least-squares circular fitting. Some experiments have been developed to empirically validate the proposal with different cylindrical targets in order to estimate the location and tracking errors achieved, which are generally less than 20 mm in the area covered by the laser sensor. As a result of the validation experiments, several error maps have been obtained in order to give an estimate of the uncertainty of any location computed. This proposal has been validated with a medium-sized mobile robot with an attached cylindrical target (diameter 200 mm). The trajectory of the mobile robot was estimated with an average location error of less than 15 mm, and the real location error in each individual circular fitting was similar to the error estimated with the obtained error maps. The radial area covered in this validation experiment was up to 10 m, a value that depends on the radius of the cylindrical target and the radial density of the distance range points provided by the laser scanner but this area can be increased by combining the information of additional external laser scanners.
    Full-text · Article · Dec 2012 · Sensors
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    ABSTRACT: This work proposes the detection of red peaches in orchard images based on the definition of different linear color models in the RGB vector color space. The classification and segmentation of the pixels of the image is then performed by comparing the color distance from each pixel to the different previously defined linear color models. The methodology proposed has been tested with images obtained in a real orchard under natural light. The peach variety in the orchard was the paraguayo (Prunus persica var. platycarpa) peach with red skin. The segmentation results showed that the area of the red peaches in the images was detected with an average error of 11.6%; 19.7% in the case of bright illumination; 8.2% in the case of low illumination; 8.6% for occlusion up to 33%; 12.2% in the case of occlusion between 34 and 66%; and 23% for occlusion above 66%. Finally, a methodology was proposed to estimate the diameter of the fruits based on an ellipsoidal fitting. A first diameter was obtained by using all the contour pixels and a second diameter was obtained by rejecting some pixels of the contour. This approach enables a rough estimate of the fruit occlusion percentage range by comparing the two diameter estimates.
    Full-text · Article · Dec 2012 · Sensors