Usage of the MANTIS Service Platform Architecture for servo-driven press machine maintenance
A forming press, is a machine tool that changes the shape of a workpiece by the application of pressure. Throughout MANTIS project, FAGOR ARRASATE’s servo-driven press machine is being analysed, in order to set up strategies that will permit to carry out an online predictive maintenance of the press machine.
The proposed solution advocates for soft sensor based algorithms. The soft sensing algorithms provide information about the physical status of the components, as well as information about the performance of the systems. These algorithms take advantage of existing or available internal signals of the systems. The objective is to estimate inaccessible states and parameters of the systems using as few physical sensors as possible to acquire the necessary signals to work with.
Currently a characterization of the system components has been done, in a scaled test bench of real press machine. A servomotor has been analysed in order to extract information about its performance during press machine work cycles, such as the applied current, voltages and generated torque. Besides, the applied soft sensor algorithm has proven to be suitable for estimating the desired magnitudes of systems when some of the system parameters are unknown.
At the same time, the mechanical part of the press machine has been analysed in order to elaborate an analytical model of the mechanical part of the system. The purpose of this development is to relate the torque generated by the servomotor with the force applied by the press ram.
This information will be used to detect effects that occur during metal forming processes, such as unbalanced forces and the cutting shock effect, allowing to carry out the maintenance of the system.
Press machine manufacturers are confronted with increasing technological and cost pressure: Many customers demand faster and ever more precise presses. The more precisely force is applied in a press machine, the higher the quality of the manufactured part is. This is why, increasing the press machines accuracy is one of the most important challenges for manufacturers of these assets. In addition, the market requires increasingly faster press machines that, at the same time, offer higher bandwidth to increase production output in existing systems.
Nowadays, the torque of the press gear shaft is measured indirectly from the force that is applied in the connecting rod. This measure is quite precise but it needs to be continuously recalibrated to obtain the accurate quality. To solve this problem, the technological answer is to measure the torque directly by using wireless sensors placed in the press gear shaft.
As a solution, IKERLAN has designed and manufactured a prototype of a shaft-adapted wireless sensor node which comprises a transducer based on torque oriented gauges, a signal conditioning circuit and a signal processing software, the latter allowing a local preprocessing and treatment of the collected data, by means of intelligent functions.
The design process has been made following two main phases:
Phase 1: Testbed validation
Before starting the development of the wireless torque sensor, a previous validation was made in testbeds both in IKERLAN. This was an initial requirement to ensure the proper functioning of gauges, generic electronics and wireless for working in press-based conditions.
With regards to wireless communications, two main challenges were tested: (i) signal attenuation due to the rotation of the emitter around the shaft and (ii) multipath fading due to RF signal reflections in the metallic (steal) elements of the head of the press in which the torque sensor is to be installed. Tests were successful being outlined that depending on the angular position of the shaft, and therefore, on the relative position of the transmission and reception antennas, more or less amount of power is received periodically.
A similar test has been performed in the Try-Out press machine from FAGOR ARRASATE. In this case, both the emitter and the reception antenna have been placed in a realistic place within the head of the press machine as in can be seen in the next figure.
Once the top cover is closed, creating a complete metallic case, it was observed how the received signal was not as clean as the one in the previous measurements due to multipath reflections. The statistical features obtained from this signals were used in the selection of the most suitable wireless communication technology to be used in the torque sensor.
Phase 2: Design and development
Once the concept and the elements of the device (gauges, conditioning and processing, radio) were validated in a rotational environment, the system design and development was started. A prototype of the wireless sensor node was designed and developed. It consists of a single PCB with the necessary interfaces to attach torque gauges, besides the conditioning, processing and wireless communication electronics. The whole system is powered by a rechargeable lithium ion polymer battery and it is encapsulated and protected by a plastic cover in the shape of the press’ secondary driving shaft, which is prepared to avoid oil leakage.
Once the design and fabrication of the wireless torque sensor was finished, the sensor was installed in the Try-Out press machine from FAGOR ARRASATE.
First tests regarding the overall performance of the sensor were successful providing signals with the torque measurements were sent to an external laptop were they could be visualised. Later, the complete validation process was carried out. This process aimed to test the accuracy of the sensor’s measurement against several torque and speeds and the robustness of the wireless communication protocol employed.
Several tests were carried out combining different values of the nominal torque and speed of the press as well as several configurations of the sensing electronics. These results were compared with an estimation of the torque at the drive shaft obtained from an overload pressure evolution analysis. Besides, some measurements regarding the performance of the wireless communication were also taken. As an example of it, Figure 6, shows the results of the test in which the maximum torque (87%) and the maximum speed (100%) were configured at the press machine.
The measured torque values at almost each stroke are close to 60kN•m which corresponds to the estimated torque values. Moreover, the clutch brake engage and disengage events are still captured.
In general terms, it is considered that the obtained results are valid, taking into account that they are compared with estimated values and not with another measurement obtained by a commercial system. However, regarding the amount of data shown at the measured torque values, some data can be missed either on the positive or the negative peaks, as the same amplitude should be acquired for each stroke. With regards to wireless communications, in general the expected performance in terms of data throughput and network availability has been achieved. However, the loss of some data packets has been detected which should be corrected in future versions.
As an important upgrade of the system, it is expected that the inclusion of antenna diversity inside the shell of the press machine will improve the communication between emitter and receiver. This new configuration should decrease the number of packets lost.
Another point of improvement is the detection of low depths of penetration. To achieve this, new tests will be performed modifying the gain parameter of the wireless sensor node and the obtained results will be analyzed.
Last but not least, the energy management of the system is a key feature if it is pretended to leave it permanently attached to the press machine’s drive shaft. With this in mind, a more energy efficient redesign will be carried out together with the development of an energy harvesting system to power up the wireless sensor node
Limit checking of measured variables in a monitored system is a method frequently used for fault detection. 3E uses it as a first step on its protocol of fault detection and diagnosis to know at which stage of a Photovoltaic plant actions need to be taken before any further deep analysis on the characteristics of the problems. Here, 3E illustrates the methodology used to apply it in their use case.
Photovoltaic (PV) plants are energy conversion systems which convert sunlight into electricity that is fed into the public utility grid. The physical structure and the important process variables of a PV plant measured when monitoring the performance of a photovoltaic (PV) plant are illustrated in Figure 1. The input variables of the process model are: the solar irradiance in the plane of the PV array (GPOA) and the ambient temperature (Tamb). Output variables from the process model point of view are: the PV module temperature (Tmod); the Direct Current voltage(VDC) and current (IDC) at the output of the PV array; the Alternating Current voltage (VAC); the power factor (PF); and the electric AC power to the grid (PAC).
Normalized performance parameters can be derived from the previously mentioned measurements and allow to quantify the energy flow and losses through the PV array per loss type. They are:
LA,V = YA,T – YA
with LA,I, LA,T, LA,V, the conversion losses due to current, temperature and voltage, respectively and Yr, YA,I, YA,T, YA the normalized energy yield from reference yield (based on irradiation from the sun), array yield after current losses, array yield after temperature losses and array yield after all array losses, respectively.
The main variables used for limit checking are solar irradiance in the plane of the PV array (GPOA), ambient temperature (Tamb), PV module temperature (Tmod), DC voltage and current at the output of the PV array (VDC, IDC) and electric AC power to the grid (PAC). The AC voltage (VAC) and power factor (PF) are not used for limit checking.
For checking the operational performance over different energy conversion steps, a performance loss ratio per step is defined. This performance loss ratio is computed for a given time span, e.g., a day up to several months. It is the useful energy lost over the energy conversion step divided by the energy available, i.e. the incoming solar energy on the PV array as represented by the solar irradiance in the plane of the PV array (GPOA); all normalized to standard rating conditions of the PV array. Accordingly, the overall performance of a PV plant is described by the performance ratio (PR), i.e., 100% minus the sum of all performance losses.
In practice, we compare the performance loss ratios from measurements to model-based performance loss ratios and thresholds. The model is fed with measured values of GPOA and Tamb. The model parameters can be set from data sheet parameters of the devices in the PV plant or identified from measurements from the plant in a healthy state. Accordingly, adequate limits can be derived either from tolerances on the data sheet parameters or from choosing percentiles from the healthy plant. Both the model-based performance loss ratios and their limit values vary depending on the PV plant and the weather during the evaluation period.
Figure 2 illustrates this application of limit checking for a PV plant located in Belgium. The current-related array losses (‘Array (current)’) in Figure 2a by far exceed the threshold. During a thorough maintenance action after this problem was detected, several smaller PV module failures were fixed. After maintenance action, all performance loss ratios were back within their expected ranges, yielding a much higher PR of 82.9% (Figure 2b).
In the frame of Mantis, the three Belgian partners (Sirris, Ilias Solutions and 3E) focused their work on exploiting intelligent data-driven technologies for failure detection and root-cause analysis. In this video we will show the work done and the results obtained within the Mantis project by the Belgian consortium:
The virtual reality and augmented reality market is developing fast both in Finland and on a global level. These technologies are emerging markets, especially on the consumer side, and are likely to affect maintenance related work in one form or another. These technologies also have a lot of innovation potential. Virtual reality and augmented reality technologies has been used in the advanced HMI approaches for the Finnish conventional energy production use case. Operation and Maintenance team of the Lapland University of Applied Sciences (LUAS) has made a technical implementation as a part of that use case. Mantis project and the VR/AR demo will be on display at the two different kind of industrial business events in Finland.
Industrial events in Kemi and Oulu during spring 2018
AR and VR demonstrators related to the Fortum use case will be presented at the “Rikasta Pohjoista 2018” (Rich North 2018) event and “Northern Industry 2018” events for industry professionals. “Rikasta Pohjoista 2018” seminar will be held in Kemi on 18th and 19th of April 2018. “Rikasta Pohjoista 2018” is the Operation & Maintenance and Mining industry event, where the theme changes every year. The theme of 2018 is “Reliability & International Mining Industry and Recycling Economy”. The event will bring together over 100 industrial professionals from mining, steel, forest, energy and recycling industry from Finnish companies. The two-day event has been arranged since 2015 at the Lapland University of Applied Sciences. Before that, the event was a one-day event, and only centered on maintenance.
“Northern Industry 2018” is the largest and only industrial trade fair in northern part of Finland. It will be held in Oulu at the 23rd and 24th of May 2018. Event gathers 5000 professionals from mining, steel and forest industry as well as from energy sector, chemical industry and from numerous service providers and equipment manufacturers. The event organizer is Expomark Oy.
Virtual Reality, Augmented Reality as Human Machine Interface
The distinction between industrial maintenance related usage of VR and AR approaches can be roughly defined between factory-floor and back-office usage, where AR is more applicable for factory-floor and on the field maintenance tasks and guidance and as well as the use in maintenance monitoring. VR is inherently more suited for back-office and other office activities such as training and planning. VR is not so handy and applicable being mobile device at the factory floor. Both AR and VR solutions could be utilized as a part of collaborative decision-making. Experts around the world could for example communicate with each other using avatars in a virtual space. AR could be used, for instance locally to observe machinery status. It could allow for new business opportunities in maintenance related support and collaboration.
LUAS first made an AR approach to the use case due to it being more suitable for use in maintenance monitoring on the field and factory floor. The AR approach was done using the Google Tango platform that consisted of a comprehensive Unity compatible AR SDK and a special hardware platform that comprised of an IR dot matrix projector and a special camera capable of measuring the time-of-flight of the independent dots projected onto a shape. The combination of the SDK and the hardware platform was used to mitigate inherent drift in any solely IMU (Inertial Measurement Unit) based positioning solution.
The AR application was named AHMI (Advanced HMI) and it would enable users to create a virtual representation of the flue gas recirculation blower at Fortum’s Järvenpää power plant and retrieve real-world measurement data onto the measurement points attached to the virtual, 3D model. It also supports adding virtual measurement points to real-world objects using real-world measurement data retrieved from MIMOSA database. The measurement data comes from Nome’s sensors that are stored in the common MIMOSA database. The measurement data is retrieved through a REST interface developed by LUAS. Figure 1 presents the 3D model of flue gas recirculation blower placed at a meeting room table.
The VR application was built solely on the HTC Vive platform, however it could be transferred to other VR hardware platforms such as Oculus, possibly even the Microsoft mixed reality platform. HTC Vive controllers were used at first, but they were replaced with Leap Motion controls, which is a structured light-based IR projection camera system intended for recognizing hand positions and gestures. This was incorporated into the VR demo system to replace the hindrance of the controllers to allow for an immediately more intuitive approaching using the user’s bare hands as a control tool. The VR version creates a virtual world that consists of the same elements used in the AR approach with added VR only features. The VR application could be used to monitor the measurement data and as a training tool for maintenance professionals for example to guide in machine disassembly.
Figure 2 shows the windows displaying real-world vibration data in the VR application. In the virtual world, the users can open and reposition these windows to their own preferences. They also have a snap functionality that allows for neat alignment of all windows. Users can manipulate these windows naturally using their own hands rendered in VR with the Leap Motion.
VR/AR -world offer new kind of experience to the operation and maintenance work and to the people who work in the factory-floor or back office. We at LUAS believe we have a good opportunity to introduce this Fortum’s Järvenpää use case demo and VR/AR technology to industry professionals in events at Kemi and Oulu. It also gives a fantastic opportunity to disseminate what we have learned during the Mantis project to a wider audience.
This use case studied the analysis of sensor data from a brake press in order to facilitate its maintenance. Brake forming is the process of deforming a sheet of metal along an axis by pressing it between clamps. A single sheet metal may be subject to a sequence of bends resulting in complex metal parts such as electrical lighting posts and metal cabinets.
These machines require very accurate control so as to ensure the required bending precision that is in the order of tens of microns. They have stringent safety requirements that also impose certain restriction on its operation. In addition to this, the production efficiency is also a very important factor in its operation.
In order to ensure production quality under these stringent requirements, it is important to make sure that all of the machines’ components are in perfect working order. The goal of this use case in the MANTIS project is to use a set of sensors to detect failures and then inform the maintenance staff of these events. In this work we used a top of the line Greenbender model to implement and test a system that could accomplish these goals.
A multi-disciplinary team participated in the research and development of this use case. The use case owner is the machine tool manufacturer ADIRA that sells machines worldwide. ADIRA’s main goal is to improve the maintenance services they provide to their customers.
Research and development in the area of communications was jointly done by ISEP and UNINOVA. This included the IoT architecture, sensors, communication’s hardware and infrastructure deployment. Data processing and analytics was performed by INESC and ISEP. INESC focused on root cause analysis (RCA), remaining useful life (RUL) forecasting and anomaly detection. ISEP worked on knowledge based techniques for failure detection by developing and testing a decision support system. In addition to this ISEP also developed a Human Machine Interface (HMI) application that provides access to IoT infrastructure and several MANTIS services, which includes the notification of failures.
JSI and XLAB also provided valuable input and feedback concerning the initial research and design tasks of the communications infrastructure (real time data transmission) and the HMI (usability).
The MANTIS project has provided INESC with the opportunity to research, test and apply machine learning techniques in a real-world setting. Tasks included the detailed study of the machine tools’ processes and components, eliciting requirements and information from the domain experts and evaluating several machine learning algorithms. Due to the many challenges that were faced in identifying, collecting and using sensor data, only anomaly detection is currently being deployed in this use case.
A set of 11 conditions are being continually monitored for anomalies. For each anomaly two thresholds are being used to identify respectively small and large deviations from the expected behavior. Whenever such a deviation is detected, an alert is dispatched to the HMI where the users are notified. These monitoring conditions should allow ADIRA to detect failures in the hydraulic system, numeric controller and several electric components. In addition to this, oil temperature and machine vibrations are also being monitored.
The MANTIS system, which includes INESC’s analytics module, has been deployed as a set of services in the Cloud. Initial tests show good false positive rates. We are now in the process of performing on-line evaluations of the detection rates. We are confident that these results will serve as an important firsts step for ADIRA to enhance its products by using more sophisticated and effective data analytics methods.
The Finnish use-case under the MANTIS project concentrates on proactive maintenance solutions in the field of conventional energy production. The industry is moving towards smaller distributed plants with less on-site staff and thus, the ability to deploy conventional CBM strategies has declined. However, availability is still a major factor in power generation efficiency and plant feasibility. Therefore, new kind of energy production asset maintenance solutions applicable also for less critical components are required.
Five industrial and academic partners, namely Fortum, Lapland University of Applied Sciences (LUAS), Nome, VTT and Wapice, form the Finnish consortium in the MANTIS project. The Finnish use-case of conventional energy production is centered on a flue gas blower in Fortum’s Järvenpää power plant. Power plants have a large array of rotating machinery, whose reliability greatly affect on the overall reliability of the plant. As such, the blower offers a valid testing environment for collaborative maintenance solutions developed by the Finnish partners. The blower has been instrumented with vibration sensors, virtual sensors and local data collectors provided by Nome, Wapice and VTT. The measurement data is stored in the MIMOSA data model based MANTIS database via REST interface developed by LUAS. The collected data can be distributed to individual systems across organizational boundaries for analysis purposes. The partners of the conventional energy production use-case have integrated their own analytic tools, such as Fortum’s TOPi, Nome’s NMAS and Wapice’s IoT-Ticket, to the MANTIS database, as illustrated in figure 1, and tested the system architecture successfully in practice.
The MANTIS project has offered a great opportunity for the conventional energy production use-case partners to develop their own HMIs that can be integrated to different fields of proactive maintenance. The development work continues in the third and last phase of the MANTIS project, as some advanced visualization approaches, including virtual reality and augmented reality applications, are piloted and integrated to the HMIs. The piloted cloud architecture from Fortum’s Järvenpää power plant will also be tested in larger scale in another entire power plant. The data collection will be extended to cover a wider range of equipment and process variables to enable plant-wide monitoring of assets and proactive maintenance strategies. In addition, the partners are developing their analytic tools further to provide solutions capable of diagnostics and prognostics required in advanced maintenance.
As we do very 4 months, we had a new consortium meeting in January. This time we met at the beautiful Ghent city, and were fantastically hosted by our partner SIRRIS.
We are approaching to the end of the project, and thus, decided not to make more parallel sessions, so everyone would perfectly be aware of the activities of all Work Packages. Also, the Open Sessions, where we always showroom our last developments in an interactive way, showed no posters but plenty of live demos.
Of course, we continue working hard till the end of April!
Next, and last meeting, in Budapest, hosted by BMU & AITIA!
MANTIS; Cyber Physical System based Proactive Collaborative Maintenance.
This project has received funding from the ECSEL Joint Undertaking under grant agreement No 662189. This Joint Undertaking receives support from the European Union’s Horizon 2020 research and innovation programme and Spain, Finland, Denmark, Belgium, Netherlands, Portugal, Italy, Austria, United Kingdom, Hungary, Slovenia, Germany.