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Robotics and Autonomous Systems

At CRAS, our mission is to develop innovative robotic solutions for complex environments and multiple operations, including data gathering, inspection, mapping, surveillance, and intervention.

We work in four main areas of research: autonomous navigation; long-term deployments; sensing, mapping, and intervention; multiple platform operations.

Latest News
Robotics

INESC TEC part of pilot experiment for underwater noise monitoring

South of São Miguel, in the archipelago of the Azores, three buoys spent 24 hours at sea collecting data - in this case, noise related to human activities that has an impact on the behaviour of cetaceans. For the first time, it was possible to collect information about underwater noise off São Miguel - more than 10 kilometres from the coast; INESC TEC joined this initiative.

02nd December 2024

Robotics

INESC TEC researchers organised underwater location challenge at the Breaking the Surface 2024 conference

INESC TEC researchers organised and carried out a technical challenge at the international conference Breaking the Surface 2024 (BTS), which took place from September 30 to October 7 in Biograd na Moru, Croatia. This interdisciplinary event (currently in the 16th edition) focuses on robotics and marine technology. This year's edition brought together 198 experts and researchers from different areas (representing more than 20 countries), who exchanged knowledge and experiences in the field of marine robotics and associated applications.

28th October 2024

Robotics

Once again, INESC TEC broke the Portuguese record with robots descending to a depth of 830m in the largest robotic exercise in the world

REPMUS - Robotic Experimentation and Prototyping with Maritime Unmanned Systems, the largest operational experimentation exercise of unmanned systems in the world, took place in Portugal yet again, between September 9 and 27 (Troia and Sesimbra).

17th October 2024

Robotics

Portugal at the forefront with new technology for measuring radon gas and improving global climate projections

For the next four years, INESC TEC will lead an international consortium with a budget of €2.6M, aimed at using advanced techniques to measure environmental radioactivity. According to estimates, by 2028, new technological solutions will be available that can improve both climate research - particularly in estimating greenhouse gas emissions - and radiological protection for the population and the environment.

02nd October 2024

The story of eight women who conquered the "unknown" – a session promoted by INESC TEC at the Glex Summit

Under the scientific coordination of Ana Pires, INESC TEC researcher, the SOE'24 event - Space, Ocean, and Earth Insights – returned to the stage of the Glex Summit, the world's largest summit in the field of space exploration. This year, the SOE focused on "Women in Exploration: Breaking Boundaries", challenging eight women to share their stories and how they have conquered the "unknown".

27th June 2024

Team
001

Laboratories

Robotics and Autonomous Systems Laboratory

Publications

CRAS Publications

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2025

DBD plasma-treated polyester fabric coated with doped PEDOT:PSS for thermoregulation

Authors
Magalhães, C; Isabel Ribeiro, A; Rodrigues, R; Meireles, Â; Alves, C; Rocha, J; Pedroso de Lima, F; Martins, M; Mitu, B; Satulu, V; Dinescu, G; Padrão, J; Zille, A;

Publication
Applied Surface Science

Abstract
The manufacturing process of thermoregulation products with polyester (PES) fabric and conductive polymers such as poly(3,4-ethylenedioxythiophene) doped with poly(styrene sulfonate) (PEDOT:PSS) with proper wearability, comfort, and high performance is still a challenge due to low adhesion, environment instability and non-uniform coatings. This study presents a simple and effective method for producing thermoregulatory PES fabrics using the Joule heating effect. Textiles treated with dielectric barrier discharge (DBD) plasma were functionalized with PEDOT:PSS incorporating secondary dopants, such as dimethyl sulfoxide (DMSO) and glycerol (GLY). PEDOT:PSS was used because it does not compromise the mechanical properties of base materials. DBD plasma treatment was applied to PES to improve the substrate's functional groups and consequently increase adhesion and homogeneity of the PEDOT:PSS on the substrate. The polymer were applied to the textiles by dip-pad-dry-cure method ensuring uniform distribution and homogeneous heating of the materials. The samples’ conductivity, impedance, potential and Joule effect, and their morphological, chemical and thermal properties were studied. Control samples without plasma treatment and secondary dopants were also prepared. The results showed that the DBD-treated samples, coated with 5 layers of PEDOT:PSS, doped with DMSO 7 % (w/v), displayed the best conductivity and Joule effect performance reaching 44.3 °C after 1 h. © 2024 The Author(s)

2024

Probabilistic Positioning of a Mooring Cable in Sonar Images for In-Situ Calibration of Marine Sensors

Authors
Oliveira, AJ; Ferreira, BM; Cruz, NA; Diamant, R;

Publication
IEEE TRANSACTIONS ON MOBILE COMPUTING

Abstract
The calibration of sensors stationed along a cable in marine observatories is a time-consuming and expensive operation that involves taking the mooring out of the water periodically. In this paper, we present a method that allows an underwater vehicle to approach a mooring, in order to take reference measurements along the cable for in-situ sensor calibration. We use the vehicle's Mechanically Scanned Imaging Sonar (MSIS) to identify the cable's reflection within the sonar image. After pre-processing the image to remove noise, enhance contour lines, and perform smoothing, we employ three detection steps: 1) selection of regions of interest that fit the cable's reflection pattern, 2) template matching, and 3) a track-before-detect scheme that utilized the vehicle's motion. The later involves building a lattice of template matching responses for a sequence of sonar images, and using the Viterbi algorithm to find the most probable sequence of cable locations that fits the maximum speed assumed for the surveying vessel. Performance is explored in pool and sea trials, and involves an MSIS onboard an underwater vehicle scanning its surrounding to identify a steel-core cable. The results show a sub-meter accuracy in the multi-reverberant pool environment and in the sea trial. For reproducibility, we share our implementation code.

2024

Depth Control of an Underwater Sensor Platform: Comparison between Variable Buoyancy and Propeller Actuated Devices

Authors
Carneiro, JF; Pinto, JB; de Almeida, FG; Cruz, NA;

Publication
SENSORS

Abstract
Underwater long-endurance platforms are crucial for continuous oceanic observation, allowing for sustained data collection from a multitude of sensors deployed across diverse underwater environments. They extend mission durations, reduce maintenance needs, and significantly improve the efficiency and cost-effectiveness of oceanographic research endeavors. This paper investigates the closed-loop depth control of actuation systems employed in underwater vehicles, focusing on the energy consumption of two different mechanisms: variable buoyancy and propeller actuated devices. Using a prototype previously developed by the authors, this paper presents a detailed model of the vehicle using both actuation solutions. The proposed model, although being a linear-based one, accounts for several nonlinearities that are present such as saturations, sensor quantization, and the actuator brake model. Also, it allows a simple estimation of the energy consumption of both actuation solutions. Based on the developed models, this study then explores the intricate interplay between energy consumption and control accuracy. To this end, several PID-based controllers are developed and tested in simulation. These controllers are used to evaluate the dynamic response and power requirements of variable buoyancy systems and propeller actuated devices under various operational conditions. Our findings contribute to the optimization of closed-loop depth control strategies, offering insights into the trade-offs between energy efficiency and system effectiveness in diverse underwater applications.

2024

Comparison of Pallet Detection and Location Using COTS Sensors and AI Based Applications

Authors
Caldana, D; Carvalho, R; Rebelo, PM; Silva, MF; Costa, P; Sobreira, H; Cruz, N;

Publication
ROBOT 2023: SIXTH IBERIAN ROBOTICS CONFERENCE ADVANCES IN ROBOTICS, VOL 1

Abstract
Autonomous Mobile Robots (AMR) are seeing an increased introduction in distinct areas of daily life. Recently, their use has expanded to intralogistics, where forklift type AMR are applied in many situations handling pallets and loading/unloading them into trucks. One of the these vehicles requirements, is that they are able to correctly identify the location and status of pallets, so that the forklifts AMR can insert the forks in the right place. Recently, some commercial sensors have appeared in the market for this purpose. Given these considerations, this paper presents a comparison of the performance of two different approaches for pallet detection: using a commercial off-the-shelf (COTS) sensor and a custom developed application based on Artificial Intelligence algorithms applied to an RGB-D camera, where both the RGB and depth data are used to estimate the position of the pallet pockets.

2024

Variable Structure Controller for Energy Savings in an Underwater Sensor Platform

Authors
Carneiro, JF; Pinto, JB; de Almeida, FG; Cruz, NA;

Publication
SENSORS

Abstract
This paper introduces a new variable structure controller designed for depth control of an autonomous underwater sensor platform equipped with a variable buoyancy module. To that end, the prototype linear model is presented, and a finite element-based method is used to estimate one of its parameters, the hull deformation due to pressure. To manage potential internal disturbances like hull deformation or external disturbances like weight changes, a disturbance observer is developed. An analysis of the observer steady-state estimation error in relation to input disturbances and system parameter uncertainties is developed. The locations of the observer poles according to its parameters are also identified. The variable structure controller is developed, keeping energy savings in mind. The proposed controller engages when system dynamics are unfavorable, causing the vehicle to deviate from the desired reference, and disengages when dynamics are favorable, guiding the vehicle toward the target reference. A detailed analysis determines the necessary switching control actions to ensure the system reaches the desired reference. Finally, simulations are run to compare the proposed controller's performance with that of PID-based controllers recently developed in the literature, assessing dynamic response and energy consumption under various operating conditions. Both the VBM- and propeller-actuated vehicles were evaluated. The results demonstrate that the proposed controller achieves an average energy consumption reduction of 22% compared to the next most efficient PID-based controller for the VBM-actuated vehicle, though with some impact on control performance.

Facts & Figures

11Academic Staff

2020

7Proceedings in indexed conferences

2020

15Senior Researchers

2016

Contacts