HMI systems in processing and food storage
A process for well thought out, fails when you are subjected to manipulation by means of often low-skilled workers. If we add to this the temporality of jobs, we find that up to 35% of incidents or causative factors of a low 'KPI' (Key Performance Indicator) in machines and processes could have been avoided if operators had understood what I said "the machine", or if the machine would have understood what the operator wanted to do. And this is basically a problem of communication between the operator and the machine. The HMI are responsible for this "translation" of intenciones-órdenes. Screens pushbuttons, indicators, now replaces the nonios, levers and mechanical devices before. Everything should be clear now, we have better resources, and more intuitive. Should we then have this high incidence of "man-machine communication" failures?
The response passes through analyzing the requirements to be met by an efficient HMI system in general, and more specifically to be used in the industry of processing and food storage. But as a preamble, let's say that they are not worth the large screens, or more detailed process graphics, if not they have been "designed" to the mentality of the operator. Many of the facilities and food processing machines are made by foreign companies, by staff who does not speak our language, and that means less even with the operators who handle our machines. It is very common to find in well-known companies of the sector with applications where the screens or signs of selectors, have terms in English or German, and when they are translated, are so bad that distort their meaning.
Requirements of an HMI system dedicated to the food industry
An efficient HMI system must comply with requirements that in the first instance can be divided into two groups: constructive factors and safety factors.
In the first case, when we speak of an HMI system to be used in food industry, we talk about equipment installed in environments where sanitary conditions are controlled. The equipment must be so easily limpiable, must prevent the entry to the interior from elements that allow the growth of bacteria. Its exterior shape should be designed by avoiding at all times the surfaces or horizontal, responsible flanges often create areas of accumulation of liquids and common breeding ground for microorganisms.
In its construction, stainless steel is the most widely used material, although some polymers began to use successfully. There are also quite a few considerations on the porosity of surfaces, gaskets, tapas, cracks etc, which force to intensify the construction details.
In addition to all this, these systems must support (during the cleaning process) direct exposure to high pressure water jets and chlorinated or acidic detergents.
We can summarize that constructively, an appropriate HMI to be used in food facilities, should be a box of stainless, little porous material of horizontal surfaces sloping, with a smooth front, if possible without departing, and with a protection minimum degree IP65 (protected the entrance of solids)(, dust and jets of water in any direction).
With regard to the factors of security, traceability is a most sought-after requirement in all processes, but even more so in all those related to human food. More and more the society requires semi-finished foods, which have less preservatives, and is cooked or heated very quickly, and this increases the risk of survival or growth of hazardous to health agencies. Cases of salmonellosis in semi-finished products or cases of poisoning from bromates in mineral water are high-profile.
Although the measures applied to the control of the production are large, this does more than reduce the chances of error, so the entire production system should be "fault tolerant". And, here is where the HMI plays its important role, not only the team, but the application itself, must be able to identify what batch was produced, under what conditions, at what times, what lots of raw material usedWhat operator intervened in the process, proportions, physical parameters, etc. This information must be recoverable in an efficient manner, and must be stored, at a minimum, a comparatively large time with respect to the cycle of use of the product made (to the date of expiration for example). All this requires the HMI, not only physical characteristics and appropriate capacities, but and more importantly still, in a clearly structured and based on the concept of traceability application.
Past and current systems
As we quote initially, the HMI is responsible for the "dialogue" between the operator and the machine. Use is basically makes of the image to send information to the operator and the touch to receive orders from this. Previously used buttons with labels, controllers with discrete buttons for certain magnitudes or levers of mechanical drives with texts. Obviously all sanitation requirements collide with these technologies.
Touch screens are currently most viewed items, with much or little intelligence, screens or touch computers translate into an image they want to say to the operator, and this is expressed by clicking on certain sites of the screen.
Not just any touch screen system is suitable for use in the food industry. According to the requirements expressed before, a smooth front is ideal, so initially we rule out already to a large part of the existing. In addition, the majority of these screens use tactile crystals of resistive technology, that have design a useful keystrokes or limited life cycle.
HMI A & R systems
On the basis of the above criteria, A & R develops mixed HMI systems, specifically designed to enrich the "dialogue" with the operator. These modular vision systems integrate a 7, 10, 15-inch touch screen or older, and also a bright pulsantería of capacitive type, all in a same front without or outgoing recesses. The use of the illuminated pushbuttons allow management more frequent or priority of the proceso-máquina, is made by these pushbuttons, eliminating the need for repeated keystrokes onscreen and increasing also the life of the same. Each push button includes an outdoor light band in yellow, green, red or blue, which can rotate to right or left, fast or slow, to intermittent fast or slow, indicate directions, staying power, etc.
They also grant the possibility of integrating pseudo-analógicos commands, such as the Rotary or linear dials of capacitive activation and lighting. These possibilities of visualization, are teaching for the operator and considerably reduces the risks of operation error, to associate light States to function or dysfunction of the machine.
These HMI screens, are offered in traditional 4: 3 format, and optionally, in the 16: 9 format, allowing an efficient playback of videos in original format.
The retro-iluminación of the screens is by LED technology, which gives a superior brightness, while minimizing the problems of lack of clarity (common problem on the screens of traditional aging lamp). Optionally these HMI can incorporate RFID readers, for fast and secure items and operator identification. A & R HMI systems are customizable and are dedicated to manufacturers of machines and facilities seeking to Excel in quality and image.
Application and software
As we quote initially, not enough big screens to make the process of efficient communication. Forms and the methodology to assign images and associated symbols States, make an application to be easily understandable and intuitive. In addition to this the possibility of viewing videos on aid or assistance in screen, give the programador-integrador, the possibilities of making a user-friendly system. The premise of traceability should be send on the entire application. From the outset, screens or States of management should plan with restricted access that memorize conveniently. The use of SQL, in records and storages of States and incidents is quite common.
But all this without losing sight of who handles the machine is not the programmer. It is usual in the programadores-integradores, to give for granted basic issues that in many cases are not for operators. In these cases, a technique that is giving excellent results, is integrated into the application, a small video of introduction, to clarify the concepts with which the application was created.
Trends and future
This is what comes:
· HMI increasingly large and Visual, seems far better method for information input to the operator, screens and more graphic and luminous state indicators.
· In the opposite direction, the push-buttons and command of capacitive type are increasingly helping to the touch. The diversity and versatility is growing exponentially.
· Touch with ability to click on more than one site simultaneously (double touch or multitouch) grant already vast new resources for the entry of data and orders.
· Camera integrated in the HMI, is another form of data entry not inconsiderable, since automatic recognition of operators, until graphic codes interpreted by the same camera, or storage of images and situations.