Touch Takes Hold, Switches Lend a Hand

Touch screens are becoming the norm, but knobs and switches are often used to improve operator comfort.

October 1, 2016

Terry Costlow

System developers are leaving no technology unturned in their effort to boost performance by improving comfort. Touch screens dominate human-machine interface (HMI) development, but rotary knobs and push buttons remain relevant, as do joysticks, which could replace steering wheels.

Ensuring that screens can be visible even in bright sunlight is the focus on Danfoss developers.

The electronic systems in cabs are evolving to meet expectations of operators used to the convenience of handheld electronics. However, evolving control strategies can’t discount user’s familiarity with knobs and buttons.

“Increasingly, the use of the basic smart phone HMI principles with touch screens tends to simplify and reduce the number of commands, making navigation easier,” said Stephan Tarnutzer, Vice President of Electronics at FEV North America. “It’s progressing, but we need to consider that many HMIs designed today represent a compromise and assume the average age of a driver/ user is slightly older than the demographic that makes the most/best use of this technology.”

Machine screens

Joysticks help OEMs differentiate their cabins. Source: Danfoss

Flat panel displays are a mainstay in cabs’ evolution. Screens are growing in size and number, and more of them are featuring touch input. This brings benefits and challenges. On the upside, operators get more information with a customizable control technique that’s extremely intuitive.

“One of the key areas that allow for better operator productivity and overall machine productivity is the ability to change screens and operator interfaces depending on the machine operating mode,” said Kirk Lola, Business Development Manager for Parker Hannifin’s Electronic Controls Division. “Touch screens allow the button menus to change along with the screens and allows an intuitive operator interface for each screen. In addition, the languages can also be changed, by the operator to suit their local language preference.”

Design teams get the challenges. Determining how operators will interact with screens is a big challenge. Another is to make sure users can actually see all the information that’s on the screen.

Push buttons from C&K can be customized with imprints and LEDs that can alert operators.

“Users want to see the displays at all times, so sunlight views and things like reflection need to be improved,” said Darren Magner, Product Manager, Electronic Displays at Danfoss. “Many people also want larger displays that show three or four things at once. Some want 10-to-12-inch displays that have modern-looking graphics and are intuitive.”

The rampant advance of touch screens doesn’t necessarily mean users will interact by touching the glass. Displays are often hard to reach, so alternative inputs are needed. Operators can then select the control mode that’s most comfortable at any given time.

“Touch screens are easier to use when vehicles are stopped, it’s not always practical to reach up for inputs. People want things like rotary knobs so they don’t have to reach up to touch screens,” Magner said. “They want something closer to where their hand rests, either with CAN-programmable rotary dial or joystick controls.”

When OEMs implement alternatives to touch input, it’s important to make sure these buttons or knobs are both simple to use and cost effective to implement. Typically, inputs can be programmed to perform different actions in various operating environments.

“These buttons can provide feedback into the control system to change and customize the display screens based on operator inputs, fault or operating conditions,” Lola said. “In addition, the function of the buttons can change based on the operating state to reduce the number of buttons and knobs. This allows for better operator productivity as the button functions can change to fit the requirements of the operating state.”

Joy to the cab

Joysticks may one day displace steering wheels, Danfoss’ Hüttmann said.

While touch-sensitive displays are a central focus, they’re not displacing the joystick’s central role in vehicle control. Joysticks continue to evolve so operators can do more with less effort. These controls are so critical that design teams are setting extremely high durability parameters for the performance of buttons and rollers on the handles.

“One million cycles has become the minimum, many are asking for more,” said Kyle Peterson, Product Marketing Manager, Americas, at C&K Components. “They also want redundant contacts and sealing to IP68 ratings. At the same time, many companies are looking for turn-key solutions, potted switches with wiring harnesses.”

Ergonomic factors are equally important. HMIs have become a differentiating factor for OEMs, who invest heavily to get a look and feel that exudes comfort and efficiency.

“Joystick grip outlines are very different from customer to customer,” said Rüediger Hüttmann, Product Manager at Danfoss. “Texture, where the buttons are, how the rollers are positioned — they are all elements of brands. It’s easy to discern one company’s grip from another grip.”

Push buttons aren’t as exotic as large screens, but the ancient touch input technology has an important role in the HMI. They can easily be upgraded to provide alerts. These switches can light up to focus the operator’s attention on a control activity that needs attention.

OEMs are asking C&K for operating lifetimes of more than 1 million cycles.

“LEDs can illuminate products independently of the switch circuitry,” Peterson said. “It just requires an extra wire or two to do an LED or a bi-color LED. You can blink them when necessary to help alert operators.”

Joysticks may see an expanded role in the future. Visibility and comfort have become focal points in cab designs, prompting some designers to focus on removing obstacles like steering wheels.

“Someone operating a combine wants an enlarged viewing angle, but the steering wheel can get in the way, so our goal is to let them steer the machine with a joystick,” Hüttmann said. “There may be a scenario where operators can disassemble the steering wheel when they’re working and re-assemble it when they’re driving. That also provides much more flexibility for the operator’s seating position, making it easier to design for ergonomics.”

This strategy highlights the rising complexity that comes when many electrical systems work together. Multiple design teams have to work together to create comprehensive architectures.

“The by-wire project can’t be one business unit; we’ve aligned the groups developing prototype joysticks and steering technologies,” Hüttmann said. “They both have to certify systems to meet safety standards.”