Multi-touch technology comes to HMI/SCADA systems
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).
A safer, more efficient operation
As has been noted, a multi-touch screen user can complete an action much faster than with a keyboard and a pointing device. Industrial users often need to zoom in and out on a particular screen. With multi-touch, this can be accomplished with simple and quick pinch in and pinch out operations. With a keyboard and pointing device, a user needs to click on a zoom command from a toolbar, and then select a percent zoom in or out using a keyboard. After the percent zoom is selected, the user can then view the new screen, which may not be what was expected, forcing the user to repeat the zoom operations.
Multi-touch technology offers a multitude of advantages
- User input three times faster than with a keyboard and pointing device
- Longer life cycle as moving parts are eliminated
- Lower costs and smaller footprint due to fewer components
- Much more suited for use in hazardous areas
- Familiar usability, similar to smartphones and tablets
- Much quicker access to information
- Reduced operator response time
- Fewer screens minimizing “back-and-forth” actions that can result in human error
- Improved safety from two-handed operation for certain procedures
- Reduced training time and costs
Additionally, simplified interfaces make it faster and easier for operators to view what they need to see by eliminating complex screen layers. Multi-touch enables menus and submenus to be replaced with symbols for key applications and screens. The ability to condense screen layers also helps reduce the need move between pages, decreasing the likelihood of error and speeding actions. For example, a user can obtain an overview of the entire command list by scrolling, which dramatically reduces required search times. Or s/he can also change pages faster and more intuitively by using swipe touches, instead of performing the sequential steps required by the traditional keystroke and pointing device commands.
Safety is a priority for industrial facilities and automation suppliers. Therefore, multi-touch HMI must incorporate measures to reduce accidents, such as requiring a second button be pressed simultaneously with the command button for the command to be initiated. This button can either be an external hard-wired push button or an on-screen button.
Two-handed operation for a multi-touch application is very helpful in industrial environments. By requiring the use of two hands for critical operations, an accidental touch won’t result in errors from changed values or parameters, or inadvertent activation of critical operations. This is particularly important with multi-touch because of its ease and speed of screen manipulation. If a machine command requires an operator have both hands away from the machine during a certain function, the multi-touch HMI screen for this application can be written to require buttons be pressed on both sides of the screen to ensure the operator can’t have hands near the machine during that particular function.
Quick and simple training
A big problem facing today’s automated plants is the rate at which they are replacing large numbers of retiring workers. Not only do new skilled workers need to be found, but these workers must be trained to use the equipment and systems they will operate.
The majority of the new users are already familiar with and adept at using industrial HMI multi-touch screens because most of them are using this technology in consumer devices. In fact, many younger workers are less savvy when it comes to keyboards and traditional pointing devices. With gestures, it is possible to define actions that are more intuitive and easier to execute. As a result, multi-touch HMI systems significantly reduce the time and cost involved in training. For more experienced personnel, multi-touch will also be a boon, as its speed and ease-of-use will simplify operator interaction.
Like many other devices and functionalities that originated in the consumer electronics world and have become standard in automation, multi-touch HMI technology offers distinct improvements in efficiency, safety, and training. Multi-touch HMI hardware and software systems are being designed specifically for the rigors of the industrial world. Their capabilities and functionality offer real benefits to automation, improving response times and ensuring certain operations are only possible after proscribed safety procedures are performed. Although we may never see a plant controlled solely by multi-touch devices, they are fast becoming an integral part of the industrial automation operator interface landscape.
Lourenco Teodoro holds a B.S. degree in computer science from the University of Texas and has more than 15 years’ experience in industrial automation. He has been with InduSoft more than 10 years and has been vice president of engineering at the company since 2008.