How have human machine interfaces improved – and why?

How have human machine interfaces improved – and why?

imageimageBy Tim Meehan, Engineering Manager Hydraulic Hybrids and David Steadman, Engineering Manager


Cruise control and an exercise in trust

Today's hydraulic human machine interfaces (HMIs) take their cues from the development of very common HMIs we take for granted, like our beloved cruise control.

As simple as cruise control is today, it didn't start that way. When cruise control was fitted to a Chrysler Imperial in 1958, it was an automobile option that met with healthy skepticism. While appealing for the long drives across U.S. interstates, fears of out-of-control crashes and speeding around tight curves also occupied consumers' minds. But as drivers experienced how the HMI worked and when to use it, they used it and then expected it on their vehicles. Cruise control became a standard feature over the years and we are surprised on a long drive when we reach for the switch on a rental car and it missing.

As cruise control became more common drivers found they could trust the behaviors of their car when under the control of this function. And soon drivers used the lever to increment forward the speed or decrement the speed back. With that growing trust came more functionality, so that today's cars can hold not just speed, but RPM as well. The function can also slow when the car ahead slows, with many more functions on the way.

Innovation led by eyes and expectations

Similar to the growing familiarity and expectation for cruise control, screen size and ubiquity also dictate how we come to interact with hydraulic controls. With functionality easier to see and easier to access, it is becoming more common. Users expect it and technicians have come to expect it as well. While cars may have a head start on with familiar HMIs, hydraulics are catching up.

Screen sizes grows. So do expectations.

image Screen size is one obvious indicator of just how much HMI has improved in hydraulic applications. Screen sizes have grown because there is more to see on a screen and more to control on a screen—and because costs have dropped. We've gone from the days of little 20-character displays to today's 7-inch VFX displays with touchscreen, and as sophisticated displays become more common and as they can do much more, users expect more complex interactions and more sophisticated control.

The technology of the screens has become better as costs have decreased. But equally important is that users have become more sophisticated. And with widening use of smart phones, our users not only accept sophisticated displays but expect a screen they can interact with.

But users also have become much more adept at manipulating screens every day. You could say the smartphone revolution has far reaching implications in everyone's life—including the life of designers and users of hydraulic systems.

Interacting with hydraulic controls

Sophisticated screens have become a common and expected part of our lives. As hydraulic controls have become more electronically controllable, we've been able to capture the control in screens.

The days when hydraulic devices were controlled by mechanical linkages and levers are giving way to electronics. Engines, too, are more electronically controllable and have been for some time, which makes it easier to interface between engine and hydraulics. And because sensors are more available and less expensive for hydraulic machines, we are able to add sensors in ways that provide vital feedback to the driver or operator. That drop in expense and increase in availability is all fairly recent.

Some hydraulic operators may miss the old days of mechanical linkages because they valued the immediate feedback. Pulling a lever on a lift truck to tilt a load resulted in the same kind of action every time. With electronic controls there is not always that same tactile feel—though that is rapidly changing as hydraulic controls become more able to respond quickly. Much of this happens at the system level. Part of our continuous improvement process is getting experience with interconnected devices as they operate in a system. We work to get the system level responses we want.

HMI impacts service and diagnostics

Simplicity and interactivity are two qualities high on the feature-list for users. But service and diagnostics are not far behind on that list for the service technicians responsible for the vehicles. Serviceability is a concern when it comes to electrohydraulics. It gets complicated quickly. But the goal, and increasingly the reality is that both diagnostics and service are getting easier and easier.

When there is a problem and a dashboard light comes on, it should be very easy to plug in, get the diagnostic code and sort the error. This becomes particularly important for vehicles that are more mature. Getting quickly to "What to fix?" and "What to replace?" is critical information for any service technician.

Feedback is critical

One critical element of HMI advances is feedback. Feedback has changed through the years, from lights to buzzers and everything in between. The critical thing is to make sure the user understands what the feedback means.

While feedback like a light lit on a dashboard can indicate a problem, more recent uses of feedback explore other aspects of how the machine is performing. In some cases operator feedback from the machine will provide information reflecting the state of the hydraulics, for instance. In some cases feedback to the operator can actually prevent them from getting into a dangerous situation. For instance, a lift truck carrying a load too high and then turning or moving too quickly.

This kind of machine response to the operator, whether it is a warning or a limiting of operations, can help operators avoid dangerous situations.

Excellent hydraulic HMI is an expectation

The growth of smart phones, the decreasing costs of screens and sensors and the increasingly electronic control of engines and hydraulics have all conspired to set a high bar for the use and adoption of hydraulic HMI in the future.