Multi-touch technology comes to HMI/SCADA systems
Multi-touch screen manipulation is three times faster than with a keyboard and a pointing device, greatly increasing operator efficiency and productivity.
Multi-touch screens have become an everyday part of life, starting with smartphones and progressing to tablets. With smartphones, multi-touch allows designers to eliminate the keypad, freeing limited phone space for a bigger screen. With tablets, multi-touch eliminates the need for a keyboard and mouse or other pointing device, greatly reducing overall size and increasing portability (Figure 1).
Unlike traditional touchscreen designs, multi-touch systems are able to recognize the position of several touch contacts at once to perform user-requested actions. The combination of touches and finger movements are called gestures. Using gestures, the user can command an entire system, with no need for a keyboard or point device. Typical examples of gestures are zoom and pan, which are commonly used to navigate the web from smartphones and tablet devices.
Although this technology is now very common in the consumer electronics market, it is still relatively new to automation. However, automation users have begun to see the advantages of multi-touch technology, primarily its much faster operation. Gestures are intuitive, easy to learn, and fast to execute. On average, a multi-touch screen user, through gestures, can complete an action three times faster than with a keyboard and pointing device. The table lists compares advantages of multi-touch to keyboard-and-pointing device combinations.
Because of these advantages, users are demanding more hardware and software for industrial multi-touch solutions. As a result, multi-touch is becoming a reality for HMI users. Most HMI/SCADA systems are now PC-based and support certain tablet user-friendly interfaces. Furthermore, with the introduction of Windows 7, Microsoft added gesture Application Programming Interfaces, which offer multi-touch screen functionality, thus enabling certain HMI/SCADA suppliers to incorporate this functionality in a seamless and cost-effective manner.
Not just another gadget
Although some see multi-touch screens as a gimmick or a “me too” product, there are real benefits to be gained from this technology. One of the areas most overlooked when considering multi-touch HMI is its ability to keep HMI hardware free from contaminants by eliminating the keyboard and pointing device.
Keyboards and pointing devices in industrial settings must be kept free of dirt and dust, extreme temperatures, chemicals, and vibrations. Existing solutions are expensive and often unwieldy, despite years of effort to improve these components. In contrast, the simplicity and minimum of parts in multi-touch screens make them much more suited for use in harsh industrial environments.
Because multi-touch systems generally eliminate the need for a keyboard and pointing device, less hardware needs to be purchases. In addition, the lifespan of the HMI is potentially lengthened by reducing the number of moving parts. Touchscreens of all types are also much easier to clean than keyboards and pointing devices, promoting the more sanitary operation critical in pharmaceutical, food and beverage, and other similar operations.
In hazardous areas such as Zones 1 or 2, keyboards and pointing devices can present further problems, and adapting these components for use in these areas is often prohibitively expensive. Multi-touch systems are inherently safer in these areas, with cost of modifications for hazardous area use low to non-existent.
A proven, user-friendly technology
Multi-touch technology for HMI systems is based on the same analog resistive or projected capacitive platforms that have been used for years in touchscreen devices such as smartphones and point-of-sale terminals. Multi-touch technology is built using these proven technologies as a foundation, with functionality extended as required to accommodate new touch features. Adapting multi-touch for industrial applications, however, can be more difficult because of the additional demands of reliability, security, and safety in these environments. As with industrial PCs, multi-touch screens must be protected and be more durable than those used for personal and commercial applications. A protective overlay of glass or polycarbonate is used to safeguard the screen from damage caused by exposure to vibrations, scratches, splashes, and extreme temperatures. The protective overlay also must be able to detect touch from bare or even gloved hands.
Along with hardware protective measures, software considerations must be taken into account. Software functionality needs to be written specifically for industrial multi-touch HMI applications because user interaction in these cases is much different than with a keyboard and pointing device. For instance, with a pointing device and keyboard, the user can acknowledge alarms through a pre-defined shortcut or by clicking specific buttons. A multi-touch implementation can define a gesture, such as drawing the letter “V” with a finger to perform the same acknowledgment. The ability to recognize gestures also allows developers to enable additional measures for safety and security, such as pushing an external hard-wired button or performing a two-handed operation to prevent critical commands from being issued accidentally.
To give a multi-touch HMI application the look and feel of familiar operations, developers must make the HMI usability similar to smartphones, tablets, and other consumer multi-touch devices. Software programs must be written for recognizing and processing touch movements involving various contact points, which are very different than those for keystrokes or pointing device. For example, software developers need to give users the ability to employ the zoom gesture to reduce or expand screen size in the same manner they do with their personal devices.
In addition, other common touch functionalities, such as tap and swipe, are needed so that the user can page through screens, lists, directories, and such. Some of these gestures are already recognized by the operating system and can be easily incorporated into the HMI. Others can be pre-defined by the HMI implementation. A modern HMI package should also provide mechanisms that enable specific HMI applications to be defined by a user’s own gestures to make executed operations more intuitive (Figure 2).