Everything at your fingertips—the avionics interface revolution

Not just for smartphones any more, touchscreens are quickly becoming ubiquitous in bizjet cockpit panels.

By David Ison
ATP/CFII. Embraer EMB120

Rockwell Collins Pro Line Fusion with touchscreen interface. Certification of this touchscreen capability is scheduled for 2013. It is expected to appear in future Pro Line Fusion cockpits.

Touchscreens have become a ubiquitous part of everyday life. Many of us have an iPhone or other touchscreen cell phone. And, of course, when you check in for a flight at an airport kiosk, the only way to get it to work is with crafty touches by the user.

When looking for an address in a strange town, touchscreen GPSs save the day—and prevent having to make that dreaded stop for directions. But one place where touchscreens haven't been in wide use is in the cockpit—until now. A touchscreen invasion has begun—and it will soon become the common avionics interface in the cockpit.

Contrary to what we might imagine, touchscreens have been around for over 50 years. The first documented touchscreen was created by E A Johnson of the UK's Royal Radar Establishment. He published several works about his invention from 1965–68. Interes­tingly, Johnson noted how this newfangled technology could be used in aviation, namely in air traffic control.

In 1971, a University of Kentucky professor named Sam Hurst created a nontransparent touch sensor for use in interfacing with pieces of apparatus. He later created a company called Elographics, which still is an innovator among touchscreen researchers. In 1972, the PLATO project gave the world a computer-assisted learning terminal. By 1974, Elographics had figured out how to make transparent touch sensors. Three years later, the company brought forth the resistive-type touchscreen, one of today's most com­monly used interfaces. (More on this later.)

The 1980s saw more interest in touchscreens, including that of computer manufacturers. Hewlett-Packard designed its HP150 touchscreen desktop in 1983. Although the system was a bit crude, with infrared sensors along the edges of the interface, the HP150 made touchscreens available to a far wider audience and in a more practical application. But it wasn't until the 1990s that touchscreens really took off.

Ever innovative Apple introduc­ed the Newton personal digital assistant (PDA) in 1993. Soon to follow was Palm with its numerous PDA devices. And the revolution began.

By 2000, touchscreen technology was quite mature and used in a wide variety of functions and settings, mainly driven by the cell phone market. Of course no one can forget the day in 2007 when Steve Jobs showed the world the iPhone. Arguably, nothing sealed the fate of touchscreens more than this handy device.

Everything since has seemingly become touchscreen in the handheld device world. Even touchscreen computers are gaining popularity. From iPads to 23-inch hi-def-screen HP touchscreen all-in-1 computers, touch has become the interface of choice.

No discussion about touchscreens is complete without knowing how these marvels work. Technically, a touchscreen system is made up of 3 distinct but intertwined pieces. The first is the actual touch-sensitive panel.

This senses the presence of your nubby fingers. The second, called the controller, converts the physical presence of your finger into something a computer can use. The third is the software that takes these messages and completes the desired tasks.

Detecting touch

A variety of technologies are used to detect touch. One of the most common is the resistive-type touchscreen. Resistive systems are essentially a sandwich of many different layers of materials. In a typical arrangement, the top layer is a flexible, transparent, synthetic surface.

Below this is a transparent conductive layer, then a transparent, nonconductive separating layer, and below these resides another transparent conductive layer. Underneath all of this are several layers of image-generating LCD material. Users not only touch, but must slightly press, the screen.

Pressure is needed to make contact between the conductive layers. When this occurs, the location of the touch is noted by the computer. If this finger "address" coincides with, say, an app "address," the appropriate software is accessed. Resistive systems are commonly used on smartphones and other handheld devices.

Another common system is the capacitive type. Al­though there is a wide range of capacitive-type interfaces, they basically all work on the same principle—they detect electrical changes on a surface.

Some kind of insulating material, such as glass, is sandwiched with a transparent conductive material. Whether you realize it or not, the human body is a conductor, so when a finger is applied to a capacitive system surface there is a change in the electrical field, or capacitance, on that surface.

Again, if the finger "address" matches that of a system function, such is executed. Capacitive systems can also perform "multitouch" functions such as the pinch function to zoom or unzoom objects on a screen. This feature also lets the finger move objects on a screen, whether to scroll through a list or move a map to see portions that are offscreen. Capacitive layers can be coupled with resistive layers to create even more multifunctional capabilities.

In general, capacitive-type touchscreens tend not to be used in handhelds because of the likelihood of accidental touches—however, they are being used in cockpit avionics. The reasoning for this is that these systems are panel mounted and thus aren't likely to succumb to "pocket dialing" or other types of accidental touch mishap, yet they are sensitive enough to use without having to cram one's finger into the screen.

Although touchscreens have been in limited use in aviation—for example, some ACARS displays are touch driven—only recently have high-tech, comprehensive, touch-based avionics systems been available to civilian users. Making recent headlines are 3 big hitters—Garmin, Avidyne, and Rockwell Collins—each releasing its own touchscreen avionics suite. And each of them is quite impressive.

Garmin GTN 650/750

Garmin Touchscreen Navigator (GTN) comes in 2 models—the 650 and the 750—both of which use capacitive interfaces. Basically, the 650 is the size of a GNS 430 and the 750 is like a GNS 530, although in both the screens are more dominant features, for obvious reasons.

Both units are easy to use and quite intuitive. For example, changing a frequency entails touching the COM radio one wants to change, at which point a numerical pad pops up with blanks for the frequency numbers. Simply punch in the numbers you need and accept. Done.

The same is true for inserting navaids or other waypoints, but a large alphanumeric keypad is displayed instead. Even the small size of the 650 isn't an obstacle to the interface.


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