In today’s Digital Age, we are increasingly plugging in to our favorite devices, whether it’s a phone, our vehicle’s dashboard or a personal computer.
The trend is also creeping into the manufacturing industry, as shop-floor machines and automation begin to copy the technological advances already found in consumer electronics. We have embraced this technology through a feature universal to all our devices: the Human Machine Interface (HMI).
HMIs have ranged in complexity through their existence, from the beginnings of the batch interface with punched cards in 1945 to the keypads and monitors, touchpads and operating panels of today.
However, new technology has introduced new challenges and opportunities in design and manufacturability.
Trends toward smaller devices with more functionality in consumer electronics are beginning to influence HMI design across industries, from automotive to medical. The approaching future of Industry 4.0 and the Internet of Things (IoT) demands more connectivity between machines and their operators. New technologies such as 3D printing and the Cloud are simplifying and streamlining design and integration.
Smart HMIs use these advancements to help improve how workers interact with their machines.
The key to getting “smart” with your HMIs is to work closely with your HMI developer, but before you approach them, you need to know what makes a smart HMI.
What Makes a “Smart” HMI
What makes a smart HMI comes down to reducing complexity of the design, increasing ease-of-use for operators and connecting the HMI itself to digital and online platforms such as Bluetooth and the Cloud.
HMIs often vary in purpose, as well as design, between applications. These applications could include:
- Consumer products
- Medical devices
- Industrial machines
- Military devices
- Transportation vehicles, from cars to planes
To meet these applications, HMIs come in three different forms, which include custom designed HMI platforms, open HMI platforms and ruggedized HMIs.
Custom designed HMI platforms are typically used by companies requiring proprietary hardware and software, such as for military and medical applications. Custom solutions demand higher development costs, but can have a reduced piece price at the production level, lowering overall cost with larger production quantities.
“The custom work is longer term, but the most cost effective,” said Ed McMahon, CEO of Epec Engineering Technologies.
“Off the shelf panel PCs or PLCs can be programmed to operate your device, but the challenge is that you have a run-of-the-mill PLC that would probably cost you around 900 dollars,” McMahon continued.
“It may cost you more to have us design a custom HMI, but when you’re done, the whole thing will only cost you 200 bucks. Long term, if you want to make 1000 of these or more a year, you’ll get your payback relatively quickly and you’ll get it built exactly the way you want it.”
Open HMI platforms are more universal and able to run a variety of software packages with popular operating systems.
Open HMIs are also ideal for companies looking to develop their own custom application software, but due to higher costs, are not effective in applications requiring long production runs.
Rugged HMIs are designed to operate in the roughest and most hazardous environments. Expected exposures highly influence the design of the rugged HMI.
“The toughest HMI application I’ve seen was military,” McMahon shared.
“We had to pass through -60° to -140° C (-76° to -220° F) and we had to pass through shock and vibe while the HMI was being used. We had to space the switches out further because if you’re driving 50mph in a Humvee, shaking around and you need to press a button, you need to be sure you press it the first time.”
What makes HMIs Smart, however, is their ability to connect to the Internet, as well as share and receive data – another application often requiring unique designs.
Building the Smart HMI – Capacitive Touch Membrane Technology
As Smart technology in the consumer electronics world continues to lead the way, engineers are getting used to smaller devices that offer more functionality.
One of the key difficulties in designing smaller devices comes is working with the available real estate for buttons and panels. Smart HMIs take their cue from their commercial predecessors, while evolving the technology for industrial use.
“One of the benefits of Smart HMIs is how we do everything with software and firmware,” said McMahon.
“Rather than have a button that’s only got one use and having to have 30 of them on the front of the interface, we design for 10 buttons, but use the display and guided light to be able to have each button equipped for several uses.”
The buttons themselves can be designed with capacitive touch membrane switches.
The capacitive touch concept replaces the traditional membrane switch with sensor technology, made from conductive carbon printed circuitry.
This design presents a number of advantages over conventional membrane switches, including:
- Sleek Appearance
- Greater Durability
- Easier Maintenance
- Flexible Customization
- Light Touch Activation
- Scroll and Slider Designs
- Multi Touch Capabilities
- Curved Interface Design
- Flexibility in Functions and Communication Interfaces
- Backlighting Options
Capacitive touch membrane technology eliminates moving mechanical components from the design, which helps extend the life of the product.
The overlay material can be glass, acrylic, polyester or polycarbonate, with the perimeter sealed to keep moisture, dust and other contaminants away from the membrane.
“There are even applications where we can make the touch screen work if you’re wearing gloves,” McMahon added.
However, with touch technology comes a potential challenge: Haptics. If the action performed is subtle, how do you know the interface acknowledged your command?
“With light and sound, we’re able to almost perfectly provide the same haptic feedback as a click,” McMahon explained. “If a light goes off and a sound is made, you’re getting a response equivalent to the tactile feel.”
Building the Smart HMI – Light Guide Film Technology
For applications that still require tactile keys with backlit artwork, light guide film is your best friend.
Large backlit areas, uniform lighting, multiple colors and proximity to other backlit areas, all within a low profile, are possible at a low cost with light guide film technology.
0.005-0.020” layers of light guide film incorporate microdots pressed into the imaged areas. Cut-outs are made in the film to place side view LEDs. Projected light travels through the light guide film to be refracted upwards to the surface of the overlay, where it hits the microdots to produce a uniform backlighting effect.
“It used to be, if you wanted to have a button light up, you would have an LED behind the button with a translucent overlay,” explained McMahon.
“Now with light guide panels, we’re able to put all of the LEDs on one side and be able to feed light through the entire design, with five or six different colors of light. This allows us to use many different technologies to guide the user through an experience with LCD touch screens.”
Opaque materials can be used to block light in undesired areas.
“Because of capacitive touch switch technology and our ability to use guided lighting inside a very small package, we’re able to register everything from very small, thin substrates on top of a printed circuit board,” said McMahon. “We really take away a lot of the problems of design for manufacturability as we are the ones doing all the designs and manufacturing, using our experience.”
Another advantage to light guide film and LCD screens comes in easy standardization of displays across a range of products.
For example, to change languages between regions, all it takes is a software update.
“If you want to sell something in Europe, you won’t have to worry about changing the part number for Germany from the west, because all you’re doing is changing the language software, which can be done in five minutes,” McMahon said.
Building the Smart HMI – Interface Software and Firmware Development
Design and programming of the interface software, as well as firmware development, is essential to the Smart HMI; what good is a body without a brain?
Electronic HMI control panel. (Image courtesy Epec Engineering Technologies.)
Examples of software and firmware include:
- User Menu Displays
- Device Inputs such as:
o Bluetooth and Wireless Communications
o Pressure/Flow Switches
o Battery Status
- Data Storage
- Language Customization
- Firm Update Capabilities
“At Epec, we work with our customers to find out what kind of input/output we’ll be working with and we’ll create all the software and firmware in the interface to display,” McMahon said.
Software and firmware for HMIs can even be personalized for customers.
“One of our customers is a big medical device manufacturer and they wanted their customer’s information to come up on the screen to make it look more personalized,” McMahon shared. “Using the software we’re able to make changes in a matter of minutes.”
Applications that could benefit from hardware upgrades can have their HMIs roll out with that hardware already part of the system at a low cost, ready and waiting to be activated with the appropriate update.
“We can put low cost touch screens in low cost applications, but not necessarily use the touchscreen when we roll it out,” explained McMahon. “Because the touchscreen is there, when the customer is ready for that, we can do the upgrade without changing hardware. The cost isn’t really that much different, so it’s worth putting in that functionality even though it won’t be used for a little while.”
Working with Epec Engineering Technologies
When looking to design your own Smart HMI, regardless of the application, it’s important to know what exactly you or your customers will need.
It’s key to present all your mechanical and electrical requirements to create a full scope of the work, so your HMI designer knows what they’re getting into.
Without a clear idea or game plan, your time to market can only extend, as your HMI designers work backward to find what you need before they work forward to completion.
“We’re working with a company right now who makes a medical device and we’ve made 5,000 units with them over the years,” McMahon said. “They wanted to have capacitive touch and we explained it to them over two weeks and they still didn’t get it. We went ahead and manufactured a prototype overlay, gave it to them and then they had that ‘aha!’ moment, where they said that’s exactly what they wanted. We sometimes have to take a step backwards, build the front of it first and let them experience it before going through with roughs and designs and showing them how it would work on their equipment.”
Prototypes for HMIs are now often done use 3D printing at Epec, due to the low cost of 3D-printed enclosures and the speed in which they can be put together with PCBs and capacitive touch overlays.
“3D printing allows us to move relatively quickly, versus the old way to make a piece of plastic and waiting weeks to get the tool done,” McMahon commented.
McMahon’s team at Epec are able to go from design to prototype and product in six to eight weeks.
“Our job is to be able to move really quickly to help our customers get to market faster,” he said. “Because we have such a library of designs built over the years, it allows us to move a lot quicker – we’re not starting from scratch every time we’re building something. We’re taking what we learned from previous designs to help us move quicker to get them to market.”
For more information about Smart HMIs, visit the Epec Engineering Technologies website. If you are ready to incorporate these technologies into your current design, you can request a free quote here.
Epec Engineered Technologies has sponsored this post. All opinions are mine. --Kagan Pittman