Eduardo Jose Lima

Development of a robot for orbital welding

Purpose – This work demonstrates the development of a robot, which was designed for the orbital welding of pipes.Design/methodology/approach – The robot consists of a small car pressed against the pipe by means of chains, which are used by the robot to move around it. To provide all necessary torch movements, the robot must have four degrees of freedom: torch travel speed, stick‐out, torch angle and lateral motion. Thus, using a look‐up table‐which was specially designed to this application‐it is possible to follow the optimal parameters (voltage, current, welding speed, torch angle and stick‐out) for each welding position (flat, vertical and overhead).Findings – The robotization of the orbital welding process brings enhancement in the final product quality, considerable increase of repeatability, reduction of rework and reduction of the weld execution time. At the very least, the robot is capable to reproduce the weld bead of the best human welder, through the use of the same paramenters contained in a t...

Trajectory generation in robotic shielded metal arc welding during execution time

Purpose – Shielded metal arc welding (SMAW) is a typical manual process with many important but dangerous applications for the welder. The purpose of this paper is to present a methodology developed for execution time trajectory generation for robotic SMAW which offers greater safety and improved weld quality and repeatability.Design/methodology/approach – The study presents a methodology developed for execution time trajectory generation for the robotic SMAW. In this methodology, while the electrode is melted the robot makes the diving movement, keeping the electric arc length constant. The trajectory is generated during execution time as a function of melting rate and independent of the welding speed, given by the welding parameters. The proposed methodology uses a variable tool center point (TCP) model where the covered electrode is considered a prismatic joint, whose displacement is determined by the melting rate.Findings – The proposed methodology was implemented in a KUKA robot. The electrode meltin...

Synthesis and PLC Implementation of Supervisory Control via Place Invariants for a Manufacturing Cell

Abstract Based on the concept of place invariants of Petri Nets, supervisors for discrete-event systems can be synthesized so as to have a set of operation constraints respected by the controlled system. The implementation of this technique in a manufacturing cell is presented, with detailed description of modeling, supervisor design and programming, in STL language, of the PLC which controls the cell. Important issues such as: supervisor permissiveness, comparative analysis with techniques based on automata, as well as the systematization of the procedure for application to other systems are also discussed.

Conversion methodologies from Signal Interpreted Petri Nets to Ladder Diagram and C language in Arduino

With the advent of electronics in the last decades, automation is becoming a wide and strong area to be studied. Its applications go from industrial machinery and robotics processes to home illumination and security system processes. Electronic components are becoming more efficient, more productive, safer and cheaper, which justifies its growing usage. Inside automation’s area is an area called discrete event systems, which presents an organized and graphical way to represent these events through a tool called Signal Interpreted Petri Nets. The purpose of this paper is to formally define Signal Interpreted Petri Net and to develop two didactic methodologies to be used in laboratory classes: to convert Signal Interpreted Petri Net into Ladder Diagram for Programmable Logic Controller and to convert Signal Interpreted Petri Net into C language for Arduino microcontroller. These methodologies will be illustrated by applying the formal Signal Interpreted Petri Net’s definition on an example.

POLIBOT – POwer Lines Inspection RoBOT

Several studies have aimed to develop robotic systems which move in transmission lines. Until this moment, all of them have a high weight and cost associated with the equipment and reduced battery autonomy time. In this context, this paper aims to propose the POLIBOT (POwer Lines Inspection roBOT) with low cost and weight, enabling the movement over the lines and an easier installation and remove.,The designed robot uses the Profiles Manufacturing Methodology (PMM). The construction of the robot mechanical structure uses modularized aluminum parts built through square profiles. Thus, it’s possible a drastic reduction in production time as well as cost reduction and weight when comparing this method with other manufacturing processes like foundry, for example. For hardware and software systems, the use of free and open source software causes a significant reduction in cost and project execution time. The benefits of using open source systems are immeasurable, both from academic and industrial applications.,The POLIBOT platform is one solution to the problem of inspection in power lines. With this robot, more lines are maintained with lower time. In its constructive aspect, the robotic mechanism is designed using principles of bioengineering. The use of this principle was successful, considering that obstacle transposition is performed with stability and low energy consumption.,The suggestion for future researches is to replace the battery for solar energy and construction in polymeric material to avoid high magnetic fields.,The commercial application is evident because manual inspections are inefficient, very expensive and dangerous. Thus, it is growing the number of researches that develop mechatronics systems for this kind of inspection.,The impact is the reduction of accidents because the present procedure requires precision of movements, where the pilot and electrical technician are close to high electrical and magnetic fields. In addition, for some tasks, the worker has to walk on the line to reach some important points. Thus, those tasks involve high risk of death.,The PMM methodology represents an innovation to the state of the art because others robotic mechanisms proposed for inspection tasks present total structure mass between 50 and 100 kg and POLIBOT has only 9 kg. Other fact is its price for implementation as this robot used the robot operating system (ROS) framework, what dispense the use of licenses. Other important features are that the robot performs the tasks autonomously, which reduces errors introduced by the operator and its low manufacturing cost as compared with other projects.

Autonomic Computing in a Biomimetic Algorithm for Robots Dedicated to Rehabilitation of Ankle

Human mobility is the key element of everyday life, its reduction or loss deeply affects daily activities. In assisted rehabilitation, robotic devices have focuses on the biomechanics of motor control. However, biomechanics does not study the neurological and physiological processes related to normal gait. Biomimetics combined with biomechanics, can generate a more efficient stimulation of the motor cortex and the locomotor system. The highest efficiency obtained through torque generation models, based on the physiological response of muscles and bones to reaction forces, together with control techniques based on autonomic computation. An autonomic control algorithm has a self-adjusting behaviour, ensuring patient safety and robot operation without the continuous monitoring of the physiotherapist. Thus, this work will identify the elements that characterize the physiological stimuli related to normal human gait, focusing on the ankle joint, aiming the development of biomimetic algorithms for robots for rehabilitation of the lower limbs. KeywoRDS Autonomic Computing, Biomechanics, Biomimetics, Mechanotransduction, Rehabilitation, Robotics

Methodology for remanufacturing of industrial robotic manipulators using open control architecture

Currently, an increasing number of robotic manipulators are discarded on the factory floor, because they are classified as unserviceable equipment, while still being able to be re-used. This problem occurs due to the fact that robot manufacturers use fully closed architecture control to their hardware and software systems. Thus, there is no interchangeability between the control cabinets and the programming languages used to generate kinematics, which make the repairs, modifications and implementations to system more expensive, due to these processes being dependent of each manufacturer. Therefore this paper proposes a methodology for the implementation of remanufacturing industrial robotic manipulators. In this methodology electronic components and electromechanical robot original can be re-used and its control systems are adapted to new technologies, using a fully open control architecture. Thus, the hardware devices are interchangeable with other processes and the programming language is not proprietary and can be modified or replaced by another.

Implementation of a SCADA System for Flexible Manufacturing Systems using object-oriented Petri nets model

Abstract This work proposes the implementation of a Supervisory, Control and Data Acquisition (SCADA) System for a Flexible Manufacturing System (FMS) based on an object-oriented Petri Net model of the plant. Considering the complexity of a FMS (different types of parts and raw materials, different schedules, processes and programs to deal with, ways of handling parts, etc.), the implementation of a SCADA System to manage and control the plant is complex and susceptible to errors, even deadlocks. The creation of a program based on a formal model capable of dealing with such complexity and problems minimizes mistakes and allows such a model to be simulated, anticipating error situations and its possible solutions. The editing and debugging processes are also facilitated, as well as the inclusion of new types of parts or processes that can be easily performed by the definition of new attributes and methods according to the model. The analysis of the program performance is carried out using a formal methodology based on the model. A case-study implementation is shown for demonstration and validation purposes.