Your Scope Needs a Natural User Interface

By Tom Lecklider, Senior Technical Editor

Before going to work this morning, you may have replied to a few e-mail messages, downloaded help pages related to your latest domestic appliance problem, and rearranged images for today’s design review presentation—all on your iPad™. Later, in the lab at work, you pushed buttons and turned knobs on your oscilloscope to achieve the desired signal acquisition conditions and trace display.

The scope and iPad represent just two of the many types of interfaces we work with. Fueling the range of variation is the trend toward natural user interfaces (NUIs) found in several consumer devices. Why does the iPad operate in the way it does? Are features such as scrolling momentum and gesture-controlled scaling just marketing gimmicks, or do they provide actual benefits?

According to Steve Ballmer, Microsoft CEO, NUIs represent a major step forward. “I believe we will look back on 2010,” he said, “as the year we expanded beyond the mouse and keyboard and started incorporating more natural forms of interaction such as touch, speech, gestures, handwriting, and vision—what computer scientists call NUI.”¹

Mr. Ballmer stated that the goal of incorporating NUI-based technologies has long been one of the most challenging problems in computer science. Indeed, Microsoft, Apple, and many other companies and academic researchers have been working on NUI-based technology for decades.

Table 1. Required Interface Characteristics Source: Nielsen and Norman Group

The many separate approaches taken to NUIs have not all resulted in systems with operations that are discoverable, consistent, and reliable. And these are only three of several attributes listed in Table 1 that are associated with a well-designed machine interface according to Dr. Jakob Nielsen and Dr. Don Norman, cofounders of the Nielsen Norman Group (NN/g).

In their article, these experts in product usability critiqued the control strategies in today’s latest consumer products with emphasis on the iPad. They argued that “in the rush to develop gestural or natural interfaces, well-tested and understood standards of interaction design were being overthrown, ignored, and violated.”²

NUI Evolution

Today, most human-computer interaction takes place via graphical user interfaces (GUIs). Succinctly, the authors explained, “The true advantage of the GUI was that commands no longer had to be memorized. Instead, every possible action in the interface could be discovered through systematic exploration of the menus.”²

During the time GUIs were becoming popular, research into aspects of NUIs was growing, much of the work on multitouch systems originating during the mid to late ’80s. In particular, Bill Buxton, principal researcher at Microsoft Research, credited Myron Krueger’s 1983 video place/video desk work with introducing many forms of rich gestural interaction—more than a decade ahead of its time. Dr. Krueger appears to be the source of the hand motions commonly used today including the pinch gesture to scale and translate objects.³

As NUI-based consumer devices have become more widely available, NN/g’s research has found them lacking in comparison to a GUI’s visibility, discoverability, consistency, and reliability. In part, these comments were based on findings from an iPad usability study that NN/g conducted shortly after the product was launched. It found that users often didn’t know what control options existed, nor could they be certain the options would work in the same way among a group of application programs.⁴

The NN/g article suggests that icons describing the gestures appropriate for the current system state should be visible. Unless some indication like this is used, the authors asked, “How is anyone to know, first, that this magical gesture exists, and second, in which settings it operates?”²

Nevertheless, NN/g did not decide that a NUI was inappropriate for iPads and similar kinds of devices, but rather that the NUI implementation was incomplete. In fact, the article on usability concluded by praising the positive aspects of NUIs:

“The new interfaces can be a pleasure to use and a pleasure to see…. The new displays promise to revolutionize media: News and opinion pieces can be dynamic, with short video instead of still photographs and…figures that can be adjusted instead of static diagrams…. The new devices also are fun to use: Gestures add a welcome feeling of activity to the otherwise joyless ones of pointing and clicking.”²

Oscilloscope UI Evolution

Benchtop Scopes

Professional-grade oscilloscopes provide several means of control including conventional front-panel buttons and knobs as well as a menu-based GUI. They do not offer true NUIs, but the graphical content of the GUIs has been enhanced by many manufacturers to create a more intuitive and informative user experience.

For example, there are lots of trigger modes and several interacting conditions that determine operation in each mode. Descriptive icons unambiguously display the relationships among these elements and allow you to make the most appropriate choice. Sometimes, the icons are dynamic as well, changing in response to control settings rather than simply indicating a certain type of trigger setup.

Chris Loberg, senior technical marketing manager at Tektronix, explained, “We support both a screen-based UI with touchscreen or mouse control and knob-based methods. Users like being able to directly move cursors and trigger points. It’s intuitive and improves productivity.

“Items related to measurement analysis, such as result reporting and mask test setups, are menu-driven and similar to the familiar PC environment. For quick evaluation of signal performance, many engineers prefer the touch and feel of front-panel knobs used to adjust things such as the vertical and horizontal settings,” he concluded.

As this example illustrates, NUI replacement of existing UIs isn’t necessarily a goal shared by all test equipment manufacturers or users. Instead, effort has been concentrated on enhancing the existing parallel knob/button and GUI control functionality that has evolved through several instrument generations.

“In addition to a menu-based GUI, Yokogawa has retained conventional knobs and buttons in its latest scopes primarily for three reasons, according to Joseph Ting, marketing manager, test and measurement:

• Tactile, physical feedback is important when operating benchtop hardware controls, particularly when simultaneously operating the DUT, probes, or other instruments.
• Pointing accuracy with a touchscreen is limited compared to conventional controls.
• There is a trade-off between responsiveness and sensitivity. In many cases, accidental touchscreen operation is not acceptable.

Mr. Ting gave several examples of ways in which Yokogawa has enhanced scope interfaces. Adding the jog-shuttle control enables you to perform both coarse and fine adjustments when positioning cursor or zoom windows. A four-directional joystick supports easy navigation of menus with checkboxes. And, the built-in graphical online help function has been expanded through block diagrams, graphical dialogs, and algorithm explanations.

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