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Supported by the modular LinX Software Suite, CrossControl’s displays connect to the machine to provide smart controls, instrumentation, engine diagnostics and advanced guidance systems. (CrossControl)

How HMI displays impact operator productivity in industrial vehicles

The latest research indicates that well-integrated HMI (human-machine interface) systems lead to more attentive users that better retain task-related information and stay focused for longer with less reported effort. These systems also fit into the wider development trends in off-highway machines that affect operator fatigue in day-to-day tasks.

Operator comfort includes more than just the cushioning in their seats; it is everything that surrounds a driver as they operate a vehicle—steering wheel height, pedal positioning, seat support, harnessing and control interface. Research from Norway and Italy as part of an overall European Union study looking into HMI in heavy machines has shown the importance of ergonomics in reducing operator fatigue. Research from Markus Wallmyr, head of UX at CrossControl and a researcher with Mälardalen University in Sweden, has demonstrated the importance of display placement in improving information detection and the effectiveness of operator aids.

Additionally, displays placed nearer the operator’s natural field of view can also increase information acquisition and retention. This can have huge benefits in productivity as machine operators can take in guidance without additionally taxing their mental capacity, leading to quicker, more accurate task completion and faster turnaround times.

Fatigue studies
In industrial operations, fatigue may be an issue even for drivers working normal, daytime shifts, as a 2008 study from Friswell & Williamson pointed to the growing number of hazards for the “wakeful-but-fatigued” driver, which was supported by Matthews et al in 2011. This issue can be alleviated by employing eye-tracking tools in the cab that monitor operators and give warnings through the display when fatigue is detected.

Under laboratory testing conditions, studies of vigilance have been especially important for investigating task-induced fatigue, as suggested by Davies & Parasuraman in 1982. In certain circumstances, even short-duration tasks requiring sustained attention can show rapid and operationally significant performance decrements, as Temple et al noted in 2000. The speed of this deterioration can be reduced if the operator is given increased support and guidance from the automation system and a well-integrated display solution, reducing his or her mental load through task automation and computer-guided operations, like depth control while digging trenches and slope control when landscaping a site.

More recently, the problem of cognitive fatigue has surfaced in a range of performance contexts other than traditional vigilance paradigms, as shown by Ackerman in a 2011 study. A variety of conditions influence the speed of the onset of fatigue including operator factors like sleep deprivation. High workload, monotonous tasks that give the machine user few opportunities to change his or her procedure appear to be the most vulnerable to the effects of fatigue, as shown in the research carried out by Matthews et al in 2010. Giving users task flexibility and variety through changes in the display can help to break up this monotony and keep them feeling fresher during longer shifts.

Conversely, tasks that offer high levels of challenge and intrinsic interest can be highly fatigue-resistant (Holding, 1983). Sleep loss, daylight, and task workload are three major areas of fatigue research, but there remain yet other sources of fatigue. Environmental stressors may produce fatigue as one of a range of five psychological symptoms, as demonstrated by Hancock in 1984. These stressors may include loud noise, high temperatures, poor quality displays that elicit eye strain, and others. Thus, reducing the stressors in the vehicle—for example, by incorporating high-quality displays and a comfortable air-conditioned, soundproofed cabin—can be of huge benefit to operators and their productivity.

Mixed-reality approaches reduce mental workload
An additional benefit of the move to all-electric vehicles is reduced operator fatigue. The change could be attributed to the lower noise and cleaner air operators experience during their shift. In recent tests, Epiroc has expressed that operators almost rush to select the newer all-electric machines for shift work, noting that after their shift they feel noticeably less tired and more alert.

Similarly, operators have shown a preference for vehicles with better integrated, more intuitive controls. Modern displays with crisper graphics and higher screen fidelity also offer reduced eye strain. A comfortable chair and controls within easy reach are part of this solution to improve operators’ long-term health. To help OEMs achieve this, the latest displays from suppliers like CrossControl can be integrated directly into the armrest to provide additional HMI solutions within easy reach of any operator.

Operating heavy vehicles, for instance an excavator, requires a high level of attention to the vehicle, situational awareness and attention to the task. The continuing digital transformation taking place in industrial vehicles aims to improve productivity and user experience, but it can also increase the operator’s mental load because of a higher demand of attention to instrumentation and controls. This can subsequently lead to a reduction in situational awareness and an increased risk of potentially fatal accidents.

One way to mitigate this effect is to display key information directly within the operators’ field of view, which enhances information detectability through quick glances. This can be done today with a modular and flexible display solution, but the industry trend is towards using mixed-reality interfaces in future implementations.

As part of this study of placement, CrossControl has utilized eye-tracking to study users’ attention to the task, situational awareness, and HMI. The results indicate the benefits of optimal display placement, and the hazards of poor location choice. Plus, the study showed the positives available with mixed-reality approaches including windscreen projected solutions and a more modern head-up display. The more advanced implementations showed a lower reported mental workload and an improved rate in detection and assimilation of information.

Advanced graphical capabilities are available on displays due to the hardware accelerated graphics and powerful onboard CPU. These allow for more dynamic wow-effect HMI solutions leading to greater information assimilation and a more positive user experience. Flexible integration allows for displays to be installed in the dashboard, A-pillar, armrest or roof of any vehicle cab to create a harmonious HMI solution that benefits users. Smaller displays can be deployed in a flexible twin-array system with each capable of all necessary tasks, allowing the user greater freedom in how they arrange their HMI and receive key information and guidance.

As more and more information is being shared with the user through displays, having them function as standalone pieces of equipment is becoming an obstacle to smooth interaction and dynamic use cases. The latest multifunctional display solutions allow OEMS to give users the resources they need for a comfortable and productive working environment.

Markus Wallmyr, head of UX at CrossControl and a researcher with Mälardalen University in Sweden, wrote this article for Truck & Off-Highway Engineering magazine.

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