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Publications

Publications by Luís Freitas Rocha

2010

Flexible internal logistics based on AGV system's: A case study

Authors
Rocha, LF; Moreira, AP; Azevedo, A;

Publication
IFAC Proceedings Volumes (IFAC-PapersOnline)

Abstract
Automated Guided Vehicles (AGV) are self-driven vehicles used to transport material between workstations in the shop floor without the help of an operator, although they can also be applied in security and exploration. They are widely used in material handling systems and flexible manufacturing systems, where production orders are constantly changing. Today, and due to the constant development of technology, sophisticated machinery is increasingly available, thus enabling manufacturing firms to achieve significant process and setup time reductions. With this development, enterprises are encouraged to leave mass production approaches and start adopting small productions lot sizes, leading to constant changes in the production operation's sequences as well as changes in the factory layout. As a consequence of the development of technology, products started to spend a big percentage of time in the queue line or being transported from one workstation/storage to another. With the introduction of AGVs production process flexibility may increase, which, in many productions processes, is still below the expectations due to the used transportation system (ex: conveyors). At the same time, with the AGVs it is possible, to decrease transportations times and costs. In this article, we will study by means of simulation, the impact of the use of an AGV transportation based system in an industrial coating application. The AGV will be responsible for transporting the parts from the system's entrance to the workstations. With this, flexibility in the production process will increase, which will be reflected in system's productivity. © 2010 IFAC.

2014

Object Recognition and Pose Estimation in Flexible Robotic Cells

Authors
Rocha, LF;

Publication

Abstract

2023

Sensor Placement Optimization using Random Sample Consensus for Best Views Estimation

Authors
Costa, CM; Veiga, G; Sousa, A; Thomas, U; Rocha, L;

Publication
2023 IEEE INTERNATIONAL CONFERENCE ON AUTONOMOUS ROBOT SYSTEMS AND COMPETITIONS, ICARSC

Abstract
The estimation of a 3D sensor constellation for maximizing the observable surface area percentage of a given set of target objects is a challenging and combinatorial explosive problem that has a wide range of applications for perception tasks that may require gathering sensor information from multiple views due to environment occlusions. To tackle this problem, the Gazebo simulator was configured for accurately modeling 8 types of depth cameras with different hardware characteristics, such as image resolution, field of view, range of measurements and acquisition rate. Later on, several populations of depth sensors were deployed within 4 different testing environments targeting object recognition and bin picking applications with increasing level of occlusions and geometry complexity. The sensor populations were either uniformly or randomly inserted on a set of regions of interest in which useful sensor data could be retrieved and in which the real sensors could be installed or moved by a robotic arm. The proposed approach of using fusion of 3D point clouds from multiple sensors using color segmentation and voxel grid merging for fast surface area coverage computation, coupled with a random sample consensus algorithm for best views estimation, managed to quickly estimate useful sensor constellations for maximizing the observable surface area of a set of target objects, making it suitable to be used for deciding the type and spatial disposition of sensors and also guide movable 3D cameras for avoiding environment occlusions.

2024

Automating Lateral Shoe Roughing through a Robotic Manipulator Programmed by Demonstration

Authors
Ventuzelos, V; Petry, MR; Rocha, LF;

Publication
2024 IEEE INTERNATIONAL CONFERENCE ON AUTONOMOUS ROBOT SYSTEMS AND COMPETITIONS, ICARSC

Abstract
The footwear industry is known for its longstanding traditional production methods that require intense manual labor. Roughing, for example, is regarded as one of the significant and critical operations in shoe manufacturing and consists of using abrasive tools to remove a thin layer of the shoe's surface, creating a slightly roughened texture that provides a better surface area for adhesion. As such, workers are typically subjected to hazardous substances (i.e., dust, chromium), repetitive strain injuries, and ergonomic challenges. Although robots can automate repetitive tasks and perform with high precision and consistency, the footwear industry is usually reluctant to employ industrial robots due to the need for restructuring. This paper addresses the challenge of re-designing the lateral roughing of uppers to allow robot-assisted manufacturing with minimal modifications in the manufacturing process. The proposed innovative system employs a robotic manipulator to perform roughing based on data collected from preceding manufacturing steps. Workers marking the mesh line of each sole-upper pair can simultaneously teach the manipulator path for that same pair, using a programming-by-demonstration approach. Multiple paths were collected by outlining a piece of footwear, converted into robot instructions, and deployed on a simulated and real industrial manipulator. The key findings of this research showcase the capability of the proposed solution to replicate collected paths accurately, indicating potential applications not only in roughing processes but also in similar tasks like primer and adhesive application.

2024

6D pose estimation for objects based on polygons in cluttered and densely occluded environments

Authors
Cordeiro, A; Rocha, LF; Boaventura-Cunha, J; de Souza, JPC;

Publication
2024 IEEE INTERNATIONAL CONFERENCE ON AUTONOMOUS ROBOT SYSTEMS AND COMPETITIONS, ICARSC

Abstract
Numerous pose estimation methodologies demonstrate a decrement in accuracy or efficiency metrics when subjected to highly cluttered scenarios. Currently, companies expect high-efficiency robotic systems to close the gap between humans and machines, especially in logistic operations, which is highlighted by the requirement to execute operations, such as navigation, perception and picking. To mitigate this issue, the majority of strategies augment the quantity of detected and matched features. However, in this paper, it is proposed a system which adopts an inverse strategy, for instance, it reduces the types of features detected to enhance efficiency. Upon detecting 2D polygons, this solution perceives objects, identifies their corners and edges, and establishes a relationship between the features extracted from the perceived object and the known object model. Subsequently, this relationship is used to devise a weighting system capable of predicting an optimal final pose estimation. Moreover, it has been demonstrated that this solution applies to different objects in real scenarios, such as intralogistic, and industrial, provided there is prior knowledge of the object's shape and measurements. Lastly, the proposed method was evaluated and found to achieve an average overlap rate of 89.77% and an average process time of 0.0398 seconds per object pose estimation.

2024

Enhancing Cobot Design Through User Experience Goals: An Investigation of Human-Robot Collaboration in Picking Tasks

Authors
Pinto, A; Duarte, I; Carvalho, C; Rocha, L; Santos, J;

Publication
HUMAN BEHAVIOR AND EMERGING TECHNOLOGIES

Abstract
The use of collaborative robots in industries is growing rapidly. To ensure the successful implementation of these devices, it is essential to consider the user experience (UX) during their design process. This study is aimed at testing the UX goals that emerge when users interact with a collaborative robot during the programming and collaborating phases. A framework on UX goals will be tested, in the geographical context of Portugal. For that, an experimental setup was introduced in the form of a laboratory case study in which the human-robot collaboration (HRC) was evaluated by the combination of both quantitative (applying the User Experience Questionnaire [UEQ]) and qualitative (semistructured interviews) metrics. The sample was constituted by 19 university students. The quantitative approach showed positive overall ratings for the programming phase UX, with attractiveness having the highest average value (M=2.21; SD=0.59) and dependability the lowest (M=1.64; SD=0.65). For the collaboration phase, all UX ratings were positive, with attractiveness having the highest average value (M=2.46; SD=0.78) and efficiency the lowest (M=1.93; SD=0.77). Only perspicuity showed significant differences between the two phases (t18=-4.335, p=0.002). The qualitative approach, at the light of the framework used, showed that efficiency, inspiration, and usability are the most mentioned UX goals emerging from the content analysis. These findings enhance manufacturing workers' well-being by improving cobot design in organizations.

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