28 research outputs found
Worker Skills and Equipment Optimization in Assembly Line Balancing by a Genetic Approach
No full textThe Assembly Line Balancing Problem (ALBP) is to determine the optimal allocation of assembly operations to a set of workstations, with respect to precedence constraints. This paper proposes a multi-objective optimization to solve the ALBP using a Genetic Algorithm (GA) approach. The aim is to minimize, besides the number of workstations, two aspects, very important from an economic point of view, but poorly treated in literature: the number of high skilled workers needed to correctly accomplish the operations and the number of assembly equipment along the line. A case study was finally discussed in order to demonstrate the capability of the proposed method in finding optimized solutions in different scenarios
Improving ergonomics in mixed-model assembly lines balancing noise exposure and energy expenditure
No full textIn the manufacturing industry, assembly processes involve most of the workforce to deal with the many manual operations. Thus, the design of workplaces must take into account ergonomics to promote workers well-being and safeguard their health and safety, also enhancing productivity. The occupational ergonomic risk not only depends on the physical workload of a task, but also on environmental characteristics of the workplace, including noise, the assessment of which may contribute to prevent workers from possible health issues associated to hearing injuries. In this regard, the present study proposes a software tool based on a genetic algorithm for solving the mixed-model assembly line balancing problem with job rotation and collaborative robots to improve workers’ ergonomics, for the evaluation of which noise exposure is also considered. In particular, the objectives of the problem concern economic aspects, which are taken into account through the optimization of the cost of the line, and ergonomics, which is pursued by reducing and smoothing both workers’ energy expenditure and noise exposure for performing operations on the line. To test the effectiveness of the proposed approach, an industrial case study is finally discussed
A proposal of an assembly workstation for car panel fitting aided by an augmented reality device
No full textIn the automotive sector, panel fitting operations represent a delicate phase of the assembly process, during which car bodywork components are manually aligned attempting to comply with spacing tolerances. Digital technologies currently promoted by the Industry 4.0 approach, such as collaborative robots and augmented reality (AR), could assist workers for reducing execution times of this "trial and error"procedure. On the one hand, human-robot collaboration (HRC) can enhance assembly process efficiency, by combining human dexterity and cognitive capabilities with robot repetitiveness and support in heavy load handling; on the other, AR can provide interactive instructions to guide workers during the process. In this regard, the present paper is focused on the development of a novel assembly workstation using HRC and AR to support workers during car panel fitting operations. The system is based on the implementation of an algorithm able to convert the values on panel spacing, which are measured by laser gauge positioned on the collaborative robot, in the instructions for the worker to correctly carry out the panel fitting operation. The paper finally presents the application of the system to a real assembly example
An Integrated Environment Based on Augmented Reality and Sensing Device for Manual Assembly Workstations
No full textOne of the main problems encountered in manual assembly workstations is human error in performing the operations. Several approaches are currently used to face this problem, such as intensive training of personnel, poka-yoke devices or invasive sensing systems (e.g. sensing gloves) used for monitoring the process and detect wrong procedures or errors in joining the parts. This paper proposes an innovative system based on the interaction between a force sensor and an augmented reality (AR) equipment used to give to the worker the necessary information about the correct assembly sequence and to alert him in case of errors. The force sensor is placed under the workbench and it is used to monitor the assembly process by collecting force and torque data with respect to an XYZ reference system; a pattern recognition technique allows the error identification and the selection of the appropriate recovery procedure. Two AR devices have been tested in this application: a video-mixing spatial display and an optical see-through apparatus, comparing the pro and cons of these two solutions. The first device includes a CCD camera positioned over the workstation and an LCD display used by the worker as a support for the correct execution of assembly operations and receiving instructions about recovery procedures. The latter consists of a head mounted display (HMD) having the capability of reflecting projected images in front of the worker’s eyes, allowing a real-world view with the superimposition of virtual objects. The CCD camera is also used for identifying errors that are not detectable by the force sensor. At the end, a case study concerning a typical assembly procedure is presented and discussed
Enhancing Ergonomics in Assembly Lines by a Genetic Approach
No full textErgonomics represents nowadays a key feature to be considered while designing manual assembly lines, as it may affect both productivity and human factor issues. Repetitive movements and handling of high weight components are frequent during assembly processes and may result in operator’s overload. To enhance ergonomics on manual stations, assembly tasks should be distributed on the line so as to smooth the workload among the different workers, based on their physiological limits given by individual characteristics. The aim of this work is to present and validate a software tool that uses a genetic algorithm for solving a multi-objective version of the assembly line balancing problem, in which one of the objective is the optimization of ergonomic aspects. In the developed system, the assignment of workers available in a company to the stations of an assembly line considers physical capabilities and limits of workers, from an energy expenditure point of view. The other objectives of the problem are the minimization of the number of stations and the distribution of assembly tasks to stations according to worker technical skills. To demonstrate the efficacy of the system, tests for different case studies are presented and discussed
Laser machining of glass microreactors: a first experimental study
No full textThe use of microreactors is one of the latest innovations in the chemical and pharmaceutical industry. One of the main issues in the fabrication of microreactors is the use of a proper technique to obtain the micro channels, in order to give them the desired shape and section so that reactants flowing inside are correctly fed through inlet branches and mixed. This paper proposes an experimental study on glass machining for the fabrication of microreactor channels through the use of a CO2 laser source. The aim of the experiments is to analyse the effects of a CO2 laser beam on glass and to study the influence of process parameters, such as laser power, focal distance and scanning speed, on the shape of the channel section and on the surface finish
An experimental analysis of laser machining for dental implants
No full textIn the recent years, the scientific progress in both technological and medical sectors has led to an evolution of materials and fabrication techniques used for dental prosthetics. This paper proposes laser subtractive process to manufacture dental implants and explores the behavior of a CO2 laser beam effects on biocompatible materials, namely zirconia and PMMA. The aims of the experiments are the study of CO2 laser beam effects on biocompatible materials and the creation of a mathematical model to relate the process parameters with groove geometry and surface finish
Critical Barriers to Industry 4.0 Adoption in Manufacturing Organizations and Their Mitigation Strategies
No full textThe fourth industrial revolution, fueled by automation and digital technology advancements, enables us to manage manufacturing systems effectively. Its deployment in enterprises has now become increasingly important in developed and emerging economies. Many experts believe that barriers associated with Industry 4.0 implementation are critical to its success. Therefore, this study aimed to identify the major hurdles to Industry 4.0 adoption and reveal their interrelationships. Initially, the literature was thoroughly studied to determine the sixteen barriers impeding I4.0 adoption. Then, based on experts’ opinions, an integrated fuzzy-DEMATEL approach was utilized to examine the most significant challenges to I4.0 deployment. The results demonstrated the distribution of barriers in which the economic dimension played a decisive role, affecting technological, regulatory, and organizational dimensions. As observed in the barrier mapping, the lack of qualified workforce was a typical adoption barrier. Finally, the mitigation strategies developed would help managers to overcome the identified critical obstacles
Real life augmented reality for maintenance
No full textA major challenge for Augmented Reality (AR) in
real life maintenance is varying lighting conditions. This
research developed a novel registration technique to use AR
effectively in real life lighting conditions, where registration
is the accurate alignment of real and virtual images. The
study has demonstrated that the registration technique can
register shiny samples and implements image enhancements
on dim samples within a Non-Destructive Testing
environment. The experimental set-up included recognition
efficiency testing on shiny and dim samples. A detailed
aerospace maintenance case study has been used to validate
the registration technique. The results show the duration of
registration reduced and the accuracy improved for both
shiny and dim samples
