An approach to task coordination for hyperflexible robotic workcells

2014 - 2015The manufacturing industry is very diverse and covers a wide range of specific processes ranging from extracting minerals to assembly of very complex products such as planes or computers, with all intermediate processing steps in a long chain of industrial suppliers and customers. It is well know that the introduction of robots in manufacturing industries has many advantages. Basically, in relation to human labor, robots work to a constant level of quality. For example, waste, scrap and rework are minimized. Furthermore they can work in areas that are hazardous or unpleasant to humans. Robots are advantageous where strength is required, and in many applications they are also faster than humans. Also, in relation to special-purpose dedicated equipment, robots are more easily reprogrammed to cope with new products or changes in the design of existing ones. In the last 30-40 years, large enterprises in high-volume markets have managed to remain competitive and maintain qualified jobs by increasing their productivity with the incremental adoption and use of advanced ICT and robotics technologies. In the 70s, robots have been introduced for the automation of a wide spectrum of tasks such as: assembly of cars, white goods, electronic devices, machining of metal and plastic parts, and handling of workpieces and objects of all kinds. Robotics has thus soon become a synonym for competitive manufacturing and a key contributing technology for strengthening the economic base of Europe . So far, the automotive and electronics industries and their supply chains are the main users of robot systems and are accounting for more than 60% of the total annual robot sales. Robotic technologies have thus mainly been driven by the needs of these high-volume market industries. The degree of automation in the automotive industries is expected to increase in the future as robots will push the limits towards flexibility regarding faster change-over-times of different product types (through rapid programming generation schemes), capabilities to deal with tolerances (through an extensive use of sensors) and costs (by reducing customized work-cell installations and reuse of manufacturing equipment). There are numerous new fields of applications in which robot technology is not widespread today due to its lack of flexibility and high costs involved when dealing with varying lot sizes and variable product geometries. In such cases, hyper-flexible robotic work cells can help in providing flexibility to the system and making it adaptable to the different dynamic production requirements. Hyper-flexible robotic work cells, in fact, can be composed of sets of industrial robotic manipulators that cooperate to achieve the production step that characterize the work cell; they can be programmed and re-programmed to achieve a wide class of operations and they may result versatile to perform different kind of tasks Related key technology challenges for pursuing successful long-term industrial robot automation are introduced at three levels: basic technologies, robot components and systems integration. On a systems integration level, the main challenges lie in the development of methods and tools for instructing and synchronising the operation of a group of cooperative robots at the shop-floor. Furthermore, the development of the concept of hyper flexible manufacturing systems implies soon the availability of: consistent middleware for automation modules to seamlessly connect robots, peripheral devices and industrial IT systems without reprogramming everything (”plug-and-play”) . In this thesis both innovative and traditional industrial robot applications will be analyzed from the point of view of task coordination. In the modeling environment, contribution of this dissertation consists in presenting a new methodology to obtain a model oriented to the control the sequencing of the activities of a robotic hyperflexible cell. First a formal model using the Colored Modified Hybrid Petri Nets (CMHPN) is presented. An algorithm is provided to obtain an automatic synthesis of the CMHPN of a robotic cell with detail attention to aircraft industry. It is important to notice that the CMHPN is used to model the cell behaviour at a high level of abstraction. It models the activities of each cell component and its coordination by a supervisory system. As more, an object oriented approach and supervisory control are proposed to implement industrial automation control systems (based on Programmable Logic Controllers) to meet the new challenges of this field capability to implement applications involving widely distributed devices and high reuse of software components. Hence a method is proposed to implement both controllers and supervisors designed by Petri Nets on Programmable Logic Controllers (PLCs) using Object Oriented Programming (OOP). Finally preliminary results about a novel cyber-physical approach to the design of automated warehouse systems is presented. [edited by author]XIV n.s

Industrial Applications: New Solutions for the New Era

This book reprints articles from the Special Issue "Industrial Applications: New Solutions for the New Age" published online in the open-access journal Machines (ISSN 2075-1702). This book consists of twelve published articles. This special edition belongs to the "Mechatronic and Intelligent Machines" section

Simulation of a low voltage customer microgrid using petri nets

With renewable energy coming to the forefront of how power is generated and delivered to the modern consumer, Microgrids are emerging as an optimal and efficient method for implementing renewables and changing the infrastructure of the dated transmission and distribution grid. This thesis work presents mathematical models of Petri Nets for the simulation of a low voltage customer Microgrid. Using previous work created in this specific field, a Hybrid Petri Net is modified such that it consists of multiple distributed generators, storage, and the utility which is referred to as the main distribution grid in this thesis. A Discrete Petri Net is developed for load shedding which is critical for simulation purposes. Two types of Scheduling are developed, heuristic and reliability ones for the Microgrid to operate. Equations for firing rates are obtained for continuous transitions. Input weather data is obtained from outside sources and modified for the simulation. Computer programs are created for the microgrid simulation and the creation and presentation of the reachability graphs. A total of twelve simulations are run with the data analyzed and reachability graphs for the hybrid and discrete load shedding Petri nets developed for two simulations

Safety and Reliability - Safe Societies in a Changing World

The contributions cover a wide range of methodologies and application areas for safety and reliability that contribute to safe societies in a changing world. These methodologies and applications include: - foundations of risk and reliability assessment and management - mathematical methods in reliability and safety - risk assessment - risk management - system reliability - uncertainty analysis - digitalization and big data - prognostics and system health management - occupational safety - accident and incident modeling - maintenance modeling and applications - simulation for safety and reliability analysis - dynamic risk and barrier management - organizational factors and safety culture - human factors and human reliability - resilience engineering - structural reliability - natural hazards - security - economic analysis in risk managemen

Synthesis of nanocomposites of difference architectures and applications based on copper, nickel and alumina

Considering that nanostructural materials are expected to have special physical and mechanical properties, in the recent years the examinations of synthesis and characterization of the nanocomposite system attracts even greater scientific interest. This paper presents production of sintered contacts materials produced from nanocomposite powders obtained by combination of thermochemical synthesis of Cu-Al2O3 powder and mechanical alloying of atomized copper powder with previously sinthetized Cu-Al2O3 powder. Produced powders were characterized by X-ray diffraction and Analytical Electron Microscopy. Characterization of sintered samples included Scanning Electron Microscopy (SEM), Energy Dispersive Spectrometry (EDS), measurement of hardness and specific electrical conductivity. By thermochemical method of Cu-Al2O3 nanocomposite synthesis, i.e. deposition from aqueous solutions, in combination with mechanical alloying, significant effects of reinforcement were achieved as a result of homogenous distribution of alumina in the nanocomposite system. In combination with conventional methods, thermochemical process of nanocomposite powders synthesis could be successfully applied for synthesis of new nanocomposite catalysts, which are characterized by a high degree of dispersion of the catalytically active component, respectively the catalyst with high activity and selectivity. The high degree of dispersion is the result of uniform distribution of the catalytically active component into alumina suspension, realized during the thermochemical treatment in the synthesis of nanocomposite catalysts. In accordance with this, the paper shows the synthesis of Ni/Al2O3 and Ni-Pd/Al2O3 nanocomposite catalysts with homogeneously dispersed Ni particles, as catalytically active component, and Pd, as activity modifier, supported on ceramic Al2O3 based foam. Namely, the previous synthesized monolith was soaked in a mixed alumina suspension with NiCl2, PdCl2 and appropriate organic additives in order to obtain a nanocomposite catalysts with homogeneous distribution of catalytically active components. Characterization of obtained Al2O3 foam, as the active catalytic components primary carrier, and synthesized nanocomposite catalysts included SEM, EDS, gas permeability and mechanical properties. Synthesis of nanocomposite materials with homogeneous distribution of particles on the nanometer level may lead to formation of new materials with improved or even unexpected properties

Modeling and Conflict Detection of Crude Oil Operations for Refinery Process Based on Controlled Colored Timed Petri Net

International audienceRecently, there has been a great interest in the modeling and analysis of process industry, and various models are proposed for different uses. It is meaningful to have a model to serve as an analytical aid tool in short-term scheduling for oil refinery process. However, in oil refinery process, there are special constraints and requirements, and the existing models cannot be applied directly. Thus, as an application in this paper, we extend the hybrid Petri net to model the crude-oil operations in oil refinery process. This Petri net is called controlled colored timed Petri net (CCTPN). In this model, a token carries both discrete and continuous properties. A token in a discrete place shows its discrete properties, while the continuous properties are captured when it is in a continuous place. A discrete transition treats a token just as a discrete one, and a continuous transition deals with it as a continuous one. In this way, we integrate the discrete and continuous processes together in the CCTPN. Based on the CCTPN, liveness for CCTPN is defined, and with the liveness definition we show how to detect conflicts in scheduling the system by using this model