Performance analysis of Ethernet Powerlink protocol: Application to a new lift system generation

International audienceTo ensure control, present lifts use the Controller Area Network (CAN) bus for transmitting commands between components. Although it is largely adopted in the industrial process, CAN is not able to guarantee a sufficient throughput to transmit multimedia data or to meet the requirements of some safety standards. In this paper, we present a transition case from electrical/electromechanical components to a networked control system. The main element we focus on in the lift system is the safety chain. We propose to build the lift communication system around real-time Ethernet for more efficiency, smartness and safety. Furthermore, the use of the openSAFETY protocol as a safety layer over the real-time Ethernet allows the achievement of the required Safety Integrity Level (SIL). This adopted solution should meet the adopted standard IEC 61508 requirements

IIoT Based Efficiency Optimization in Logistics Applications

The Industrial Internet of Thing (IIoT) approach to an Industry plant design, devises a comprehensive interconnection of the system components, from sections up to single devices, in order to get a general and punctual understanding of the process. Such an intelligent network, mostly based on Ethernet basic layers, when properly conceived, should be able to add relevant value to the plant operation. This paper shows how, within the IIoT frame topics, the plant efficiency can be addressed and bring relevant improvement. The reason is that variables directly related to the energy consumption, such as current, electric power, actuator and motor torque, speed, etc., can be timely and easily monitored in the entire plant, since they are already conveyed on the network, due to real time control and diagnostics purpose. A power consumption diagram can be derived, and give hints on how to optimize operations, based on some efficiency index. The paper, after a general discussion, proves it with practical examples based on a Gantry robot, driven in an EtherCAT based automation network, and on the stacker cranes of an automated warehouse

Real-Time Ethernet Networks: a practical approach to cycle time influence in control applications

Vivemos num mundo cada vez mais digital e informatizado onde existe uma constante necessidade de interligação entre tudo e todos. Os sistemas robóticos modernos não escapam a esta necessidade e, por isso, é preciso adaptá-los. Existem no mercado várias soluções de redes de comunicação de tempo real, já bem estabelecidas, mas em todas se encontra a mesma lacuna: a escassez de material educativo acerca delas. Este documento pretende apresentar as duas soluções propostas para colmatar um pouco esta lacuna na rede EtherCAT e demonstrar o trabalho de pesquisa e estudo preliminar efetuado para suportar e servir de ponto de partida para o desenvolvimento aprofundado de uma das soluções. Nos capítulos seguintes será explicitado o contexto e motivação para a realização deste projeto, os objetivos que propomos alcaçar, uma descrição do problema incluindo a sua caraterização, uma apresentação não exaustiva da tecnologia por detrás da rede EtherCAT, a explicação das soluções propostas e, por fim, um planeamento de tarefas e objetivos com calendarização dos mesmos

A new method for motion synchronization among multivendor’s programmable controllers

This paper is aimed at increasing the number of possible architectures of distributed control systems by investigating and developing novel methods for the synchronization of axes between PLCs and iPCs of different vendors. In order to find a global solution to this problem, particular attention has been focused on programmable controllers that can manage axes by means of point-by-point control or motion instructions. Two synchronization algorithms have been developed and validated for real and virtual axes; they differ in computational load so that they can be used with programmable controllers having high or low computational performances

Formal Modeling and Verification of Motor Drive Software for Networked Motion Control Systems

Abstract: This paper presents a model-based approach to the design and verification of motor drive software for networked motion control systems. We develop a formal model for an Ethernetbased motion system, where, using timed automata, we describe the concurrent and synchronized behaviors of the components, i.e., motion controller, motor drives, and communication links. The drive, in particular, is modeled in enough detail to accurately reflect the software implementation used in a real drive. We use the design of multitasked drive software with fixed-priority preemptive scheduling. With UPPAAL model checking, we verify the precision and accuracy of the rendered motion in terms of the requirements on the actuation delay at each drive and the actuation deviation between different drives, respectively. The analysis results demonstrate the benefits of our model-based approach in the safety verification and design space exploration of motor drive software. We show that it is possible to verify deadlock freeness and real-time schedulability in an early design phase. And, for varying number of drives and size of messages, we can successfully determine the combination of task periods that leads to the best precision and accuracy

Toward a Holistic Delay Analysis of EtherCAT Synchronized Control Processes

This paper analyzes the end-to-end delay of EtherCAT-based control processes that use the events of message frames and global clock for synchronized operation. With the end-to-end delay defined as the time interval between the start of a process cycle and the actual input or output, we develop a holistic delay model for control processes in EtherCAT, by taking into account the time for in-controller processing, message delivery, and slave-local handling. Based on the measurements from a real EtherCAT control system, we discuss the average and deviation of the process delay as we vary the number of slaves and process cycle time. The experiment results show that the output delays are mainly increased by the average controller delay, whereas the input delays are more affected by the deviation rather than the average of the controller delay. Our in-depth analysis on the controller reveals that DMA time chiefly enlarges the controller delay for increasing number of slaves, while task release jitter is the main cause of the increased delay for longer cycle time. The presented delay model and evaluation results can be essentially used for the design of EtherCAT-based automation that requires highly synchronized operations, such as for coordinated motion and high-precision data sensing

A distributed framework for the control and cooperation of heterogeneous mobile robots in smart factories.

Doctoral Degree. University of KwaZulu-Natal, Durban.The present consumer market is driven by the mass customisation of products. Manufacturers are now challenged with the problem of not being able to capture market share and gain higher profits by producing large volumes of the same product to a mass market. Some businesses have implemented mass customisation manufacturing (MCM) techniques as a solution to this problem, where customised products are produced rapidly while keeping the costs at a mass production level. In addition to this, the arrival of the fourth industrial revolution (Industry 4.0) enables the possibility of establishing the decentralised intelligence of embedded devices to detect and respond to real-time variations in the MCM factory. One of the key pillars in the Industry 4.0, smart factory concept is Advanced Robotics. This includes cooperation and control within multiple heterogeneous robot networks, which increases flexibility in the smart factory and enables the ability to rapidly reconfigure systems to adapt to variations in consumer product demand. Another benefit in these systems is the reduction of production bottleneck conditions where robot services must be coordinated efficiently so that high levels of productivity are maintained. This study focuses on the research, design and development of a distributed framework that would aid researchers in implementing algorithms for controlling the task goals of heterogeneous mobile robots, to achieve robot cooperation and reduce bottlenecks in a production environment. The framework can be used as a toolkit by the end-user for developing advanced algorithms that can be simulated before being deployed in an actual system, thereby fast prototyping the system integration process. Keywords: Cooperation, heterogeneity, multiple mobile robots, Industry 4.0, smart factory, manufacturing, middleware, ROS, OPC, framework