Nuno Mendes

Universidade NOVA de Lisboa | NOVA · Department of Mechanical and Industrial Engineering (DEMI)

The detection of internal defects, not visible to the naked eye from the outside of materials, using non-destructive testing (NDT) are increasingly requested by industrial processes. This study proposes a novel methodology for acquisition and processing of images from a thermographic camera using computer vision methods to test composite materials...

The human–robot collaboration (HRC) solutions presented so far have the disadvantage that the interaction between humans and robots is based on the human’s state or on specific gestures purposely performed by the human, thus increasing the time required to perform a task and slowing down the pace of human labor, making such solutions uninteresting....

The interaction between humans and collaborative robots in performing given tasks has aroused the interest of researchers and industry for the development of gesture recognition systems. Surface electromyography (sEMG) devices are recommended to capture human hand gestures. However, this kind of technology raises significant challenges. sEMG signal...

An innovative pilot installation and eddy current testing (ECT) inspection system for laser-brazed joints is presented. The proposed system detects both surface and sub-surface welding defects operating autonomously and integrated with a robotized arm. Customized eddy current probes were designed and experimentally validated detecting pore defects...

Automobile laser brazing remains a complex process whose results are affected by several process variables that may result in nonacceptable welds. A multisensory customized inspection system is proposed, with two distinct non-destructive techniques: the potential drop method and eddy current testing. New probes were designed, simulated, produced, a...

In this paper we present a novel strategy and implementation of autonomous navigation for the Pepper robot. The proposed solution is modular and relies on the proper integration of existing Pepper functionalities. The human interacts with the robot using voice and/or gesture commands to setup the robot functionalities. An example use case demonstra...

The use of gestures as interface between humans and robots to facilitate communication between them is a long-sought goal. Although many gesture solutions have been presented, none of them cope entirely with wrong gesture recognition. This study proposes a novel electromyography (EMG) prototype sensor to capture gestures and also algorithms and pro...

This paper presents a literature review on pattern recognition of electromyography (EMG) signals and its applications. EMG technology is introduced and the most relevant aspects for the design an EMG-based system are highlighted, including signal acquisition and filtering. EMG-based systems have been used with relative success to control upper-and...

The paradigm for robot usage has changed in the last few years, from a scenario in which robots work isolated to a scenario where robots collaborate with human beings, exploiting and combining the best abilities of robots and humans. The development and acceptance of collaborative robots is highly dependent on reliable and intuitive human-robot int...

A flexible programming and orchestration system for human-robot collaborative tasks is proposed. Five different interaction modes are suggested to test two Task-Managers (TMs) acting as orchestrators between a human co-worker and a robot. Both TMs rely on the task-based programming concept providing modular and scalable capabilities, allowing robot...

This paper presents an intuitive human-robot interaction (HRI) framework for gesture and human behavior recognition. It relies on a vision-based system as interaction technology to classify gestures and a 3-axis accelerometer for behavior classification (stand, walking, etc.). An intelligent system integrates static gesture recognition recurring to...

The ability of efficient and fast calculation of the minimum distance between humans and robots is vitally important for realizing a safe human robot interaction (HRI), where robots and human co-workers share the same workspace. The minimum distance is the main input for most of collision avoidance methods, HRI, robot decision making, as well as ro...

Gesture recognition is more reliable with a proper motion segmentation process. In this context we can distinguish if gesture patterns are static or dynamic. This study proposes a gesture segmentation method to distinguish dynamic from static gestures, using (Inertial Measurement Units) IMU and Electromyography (EMG) sensors. The performance of the...

A solution for intuitive robot command and fast robot programming is presented to assemble pins in car doors. Static and dynamic gestures are used to instruct an industrial robot in the execution of the assembly task. An artificial neural network (ANN) was used in the recognition of twelve static gestures and a hidden Markov model (HMM) architectur...

This survey presents a literature review on the machine and control systems applied in friction stir welding (FSW) with a special focus on the new trends, i.e., using robots and force control. The physical process of FSW is described and the main parameters that are relevant to select a machine and establish a control system are highlighted. The pa...

Purpose – The purpose of this paper is to achieve reliable estimation of yaw angles by fusing data from low-cost inertial and magnetic sensing. Design/methodology/approach – In this paper, yaw angle is estimated by fusing inertial and magnetic sensing from a digital compass and a gyroscope, respectively. A Kalman filter estimates the error produce...

The relevance and importance of industrial robots in manufacturing has increased over the years, with applications in diverse new and non-traditional manufacturing processes. This paper presents the concept and design of a novel friction stir welding (FSW) robotic platform for welding polymeric materials. It was conceived to have a number of advant...

The aim of this study is to examine the main factors affecting friction stir welding (FSW) of acrylonitrile butadiene styrene (ABS) plates, performed by a robotic system developed to this purpose. Welds were carried out using a tool with stationary shoulder and an external heating system. The welding parameters studied were the axial force, rotatio...

The relevance, importance and presence of industrial robots in manufacturing have increased over the years, with applications in diverse new and nontraditional manufacturing processes. This paper presents the complete concept and design of a novel friction stir welding (FSW) robotic platform for welding polymeric materials. It was conceived to have...

The aim of this study is to examine the effect of main friction stir welding (FSW) parameters on the quality of acrylonitrile butadiene styrene (ABS) plate welds. Welds were carried out in a FSW machine, using a tool with a stationary shoulder and no external heating system. The welding parameters studied were the tool rotational speed which varied...

This paper presents a method for robot self-recognition and self-adaptation through the analysis of the contact between the robot end effector and its surrounding environment. Often, in off-line robot programming, the idealized robotic environment (the virtual one) does not reflect accurately the real one. In this situation, we are in the presence...

robotic friction stir welding - video

Purpose The purpose of this paper is to present a CAD‐based human‐robot interface that allows non‐expert users to teach a robot in a manner similar to that used by human beings to teach each other. Design/methodology/approach Intuitive robot programming is achieved by using CAD drawings to generate robot programs off‐line. Sensory feedback allows...

More and more, new ways of interaction between humans and robots are desired, something that allow us to program a robot in an intuitive way, quickly and with a high-level of abstraction from the robot language. In this paper is presented a CAD-based system that allows users with basic skills in CAD and without skills in robot programming to genera...

Increasingly, robot programs are generated off-line, for example, through a virtual model of a robotic cell. However, when the virtual model does not reproduce exactly the real scenario or the calibration process is not performed correctly it is difficult to generate reliable robot programs. In order to circumvent this problem, it was introduced se...

Today, industrialized countries are facing a major problem, the lack of skilled engineers. Despite the increasing demand for engineers in the labor market, the number of students going to engineering courses has been declining. This paper reports some initiatives carried out by the industrial robotics laboratory of the University of Coimbra (Portug...