By Heiko Stichweh and Matthias Theßeling
The interconnection of production systems has become common practice in industry. In systems used to control material flows, for example, this serves to ensure a continuous supply of the materials and components required. The fact that all materials are available at the right place and at the right time also means increased efficiency and productivity. The downside of these systems is that the entire plant comes to a standstill when only one component fails, leading to cost-intensive production downtime. In addition, the subsequent implementation of changes to the routing of material flows can be very cost-intensive and time-consuming. With this in mind, future material flow systems need to be capable of flexibly adapting to changes and failures, and they must be connected seamlessly to ensure competitive production.
New warehouse logistics
Production and logistics processes will experience a fundamental change in the next decades as a result of the new technical possibilities arising from the 4th industrial revolution. Connected machines, warehouse systems, products and devices will merge into cyber-physical systems (CPS). They will exchange information, trigger actions and control one another independently, thus unlocking a completely new production logic.
With horizontal material flows in particular, centrally controlled, inflexible solutions may soon be a thing of the past, given that in the future, goods and materials will be able to make their way through production processes on their own. The research project "networked cognitive production systems" (netkoPs) funded by the Federal Ministry of Education and Research (BMBF) aims to develop such a novel material flow system with decentralized control for production and intralogistics. In collaboration with their project partners Continental, Dream Chip, Gigatronik, ITA, Transnorm and Lenze as specialists in the field of motion centric automation, the Institut für Integrierte Produktion Hannover (IPH) and the Institute of Transport and Automation Technology (ITA) of the University of Hanover work together to turn this goal a reality.
The fundamental element of the netkoPs material flow system is the consistent networking of conveying and production equipment, enabling a parallel flow of materials and information. The material flow is controlled via an innovative, decentralized product routing solution that is integrated into every conveying element, planning the routing of the goods while exchanging information with the respective adjacent devices. This eliminates the need for a higher-level, central material flow control system.
Flexible material handling thanks to the conveying matrix
In conjunction with routing, networking and data communication, the conveying matrix with its decision-making capabilities is one of the central elements of cyber-physical conveyor technology. The conveying matrix (Figure 1, left-hand side) consists of many small-scale conveying modules that are capable of interacting with one another (Figure 1, right-hand side) and triggering conveying and swivel movements independently. Each of the conveying modules is equipped with one conveyor drive and one swivel drive. By connecting several conveying modules in one matrix network, it is possible to implement local decision-making and situation-specific routing and thus achieve a smooth flow of materials. As a result, the conveying matrix allows for new intralogistic degrees of freedom, offering the possibility of conveying, infeeding and outfeeding, turning, aligning, congesting, separating, merging, sequencing and storing the goods and materials. In addition to routing, networking and data communication, the research project also focuses on developing, implementing and validating a new drive system.
The implementation of intralogistic functions and the economic usability and feasibility of the conveying matrix results in high requirements for the actuators and the drive and control technology of the individual conveying modules. In addition, limited space means that highly integrated drive concepts with high performance and efficiency are required in order to mitigate the effects of heat loss (motors and converters). And of course, the drives also need to comply with the relevant technical requirements to make sure that they are capable of implementing the intralogistic functions in a precise manner. This includes a dynamic, speed-synchronous operation of several conveyor drives (for example for conveying and sequencing) and exact aligning/positioning of swivel drives (for example for turning). Due to the great variety of individual conveying modules, another important factor is that the modules may not be too cost-intensive in order to be able to operate the system in a profitable manner.
Newly developed conveyor drive
Figure 2 shows the prototype of the newly developed conveyor drive. The motor of the conveyor technology was developed further based on the fundamental principle of the vernier motor. A vernier motor is a combination of a magnetic drive and a synchronous motor, which enables an extremely high torque density. With this motor, an elaborate mechanical drive is no longer necessary, as the motor can be used as a direct drive.
This technology makes it possible to achieve high torques even at low speeds, making it ideally suited to the requirements for conveyor technology. Drives are no longer necessary, and the motor is also designed as an external-rotor motor. This means that the center motor axle is fixed, while the rotatory energy can be transferred directly to the conveyed goods via the motor's rotating outer shell. This and other special design features, such as the design option for good sensorless control and monitoring, make up a compact direct drive with particularly high performance density, overload capacity and excellent energy efficiency.
The motor is fed by an equally innovative converter or inverter that is integrated in the lower part of the conveying module. The dedicated sensorless motor control makes it possible to do without a rotary and position sensor. Such a sensor would not only put the system's economic viability at risk, but it also takes up a lot of space and is very susceptible to interferences. Another advantage of the sensorless motor control is that it complies with the requirements for high speed accuracy, positioning capabilities and dynamics, thus enabling the speed and position-synchronous movement and positioning of several modules in the network.
The individual conveyor drives are connected to each other and to the conveyor elements in the conveying matrix to enable an exchange of information and decentralized product routing. In addition to the exchange of data, the system also allows for an optimized exchange of energy - the braking energy of conveyed goods can be converted and directly used to accelerate other products and materials. The system cost can be significantly reduced by omitting drives and sensors, and thanks to the innovative motor and converter design, bringing the vision of operating a conveying matrix economically within reach.
Summary and outlook
In order to ensure competitive production processes in the future, material flow systems need to be flexible and seamlessly networked. The netkoPs research project aims to develop a material flow system with decentralized control for this purpose. Based on human cognitive capabilities, machinery, handling and conveyor systems will use this solution to communicate, and react and adapt to new conditions in an intelligent manner.
The conveying matrix can be retrofitted to existing plants and integrated into new factories. Inflexible production processes at the conveyor belt will thus soon be a thing of the past. The solution also boasts advantages in other areas, such as parcel distribution centers - spacious sorting devices, in which goods circle around until they reach their destination via tilt trays, are no longer necessary.
Background: Lower Saxony researching factories that think for themselves
The "networked, cognitive production systems" (netkoPs) research project was initiated on November 1, 2013 and runs for three years. As part of the "Industrie 4.0" research program, it is funded by the Federal Ministry of Education and Research (BMBF) and supported by the project sponsor Karlsruhe. The drive technology that is used to drive and control each of the conveying elements individually is developed by Lenze SE. The Institute of Transport and Automation Technology (ITA) of the Leibniz University of Hanover writes the algorithms that are needed to ensure independent routing, and Dream Chip Technologies GmbH (Garbsen) implements and integrates them into the hardware. Transnorm System GmbH (Harsum) then builds the prototype of the conveying matrix, which is to be tested by several application partners, including Continental Automotive GmbH. Continental supports the project from the very start with its vast production experience, contributing to defining requirements and checking them subsequently. The findings of the research project are set to offer numerous advantages to manufacturing companies across all industries. The researchers’ goal includes making the conveying matrix available for retrofitting to existing plants and integration into new factories - factories that think for themselves.
Heiko Stichweh (left), Displinary Manager of the Innovation division at Lenze, and Matthias Theßeling, PhD student at Lenze.
NetkoPS: material flow system with decentralized control for production and intralogistics © VDMA
Research and innovation are vital if Industrie 4.0 is to be integrated successfully into companies' everyday activities. The netkoPs research project implements one of the core aspects of Industrie 4.0: the idea that machines and work pieces can control their production independently. To do this, the project is developing a locally-controlled material flow system that is based on the cognitive skills of humans and can even be retrofitted to existing systems. The results of the project are particularly of interest to VDMA members because they enable flexible and uncoupled production processes.