This is the second of three related articles. If you haven't seen it already, perhaps you should read the first installment.
Some devices have very simple interfaces: they're either running or not, so they need a switch. But then, maybe there is a thing you make stronger a weaker, so you add a dial or a slider. And maybe it can run a couple of ways, so you add a selector dial. Maybe the user needs some progress feedback, which means some kind of clock.1 And so on.
In my youth, a typical washing machine, dryer, or dish washer had a handful of controls supporting as many as a dozen modes of operation, and that felt like progress compared to the kit my parents grew up with. Yeah! Living in the future!
This is the control panel from the dryer at Casa NoSwampCoolers. There is a
power button and a separate start button (because power means the controls
are active and start means the machine is running), a mode-select dial with
fourteen options, four categories of adjustable parameters (some of which only
apply to some modes), six additional Boolean settings (again, applicability
varies), and a time-display-and-control group. I'm not sure if that reaches a
thousand front-panel accessible combinations but it is certainly hundreds. And
there are extended features only available with an app.2
Okay, so we've established that (at least some) modern appliances require complex interfaces. But we've also established that you can build the interface into the device. So, how does that justify connecting it to your carry-around-computer-thingy?
Well, we're in engineering trade-offs land. We get to compare costs, convenience, maintainability, utility, and user preferences between alternatives. And how we rate some of those depend on how the machine works. If you have to physically load and unload a device for it to be useful (as in clothes washers, clothes dryers, and dish washers) then remote start is less helpful compared to remote access to your car's defroster.
- Settable defaults are nice
- In principle, to know that my dryer is doing what I want I have to memorize the desired state of approximately a dozen controls, and check each of them on the control panel. In practice I memorize the smaller number of things it takes to get from "just booted" to the state I want: switch the mode to "Speed dry", set the temperature to low, increase the time, then go. Wouldn't it be nice if I could set the default state or name several default states? If there is a win here it's for "smart"
- Control panels cost money and represent additional points of failure
- Controls are a pain. They have to be robust, when the options are discrete they should be unambiguously in one state or another, they should give clear feedback, and in the physical realm all of that takes engineering. The cheapest switches and dials general lack something. I'm not in this business, but over the years I've talked to people who are. Controls often represents a surprising portion of the cost. To be sure, digital interface can fail too. If the magic smoke gets out of the computer on the device, your done with either kind of controls.3 If your phone smokes, you need a different interface device. At least partly in favor of "smart"
- You're right there anyway
- As mentioned above, some devices require your presence. For those I really want a on-device control set for the primary features. Because otherwise they require the presence of you and your phone or tablet. But I'm pretty happy with our machine that presents the big easy stuff on the panel and leaves the fiddly choices for a computerized interface. Definitely favors some physical controls on machines you have to attend in person
- Translation
- Did you notice that the controls on my washer are labeled in English? That's built into the physical medium, so a French-speaking, would-be user can't just change it. Now the company could (and presumably does) provide that part in multiple language variants, but that becomes a logistical headache and thus a cost and you can't easily switch back and forth. Adding translation to a software interface is not free, but (with some support from your OS or framework) it can be relatively painless, and users can change the language on demand. That's cool. A reason for pixelated UI, where ever the display is mounted
- Maintainability
- Once a physical control panel is engineered, manufactured, and sent into the wild changes are hard and expensive. In principle, software changes are easier, though if the software in question resides on the machine, you'll need to provide a firmware-update facility of some kind.4 If there is a win here it's for "smart"
- "Just give it a proper display" is a good idea, but you already have a display...
- There is nothing magical about using your phone or your tablet that enables digital UI. You could put a display (probably a touch display) on the device and then have a programmed interface. Yeah!. But ... how many pixels are you willing to pay for? And on every appliance in your house? what about physically small devices like my espresso machine? And those question lead to the idea of sharing a single interface device. Your potential customers almost all have a phone or tablet already,5 why not just borrow that display? Favors "smart"
- Human stuff
- This is hard for me. I'm not trained in UI/UX. I haven't done any surveys. Basically this whole essay has been me ranting about how I feel. But people sometimes care about appearance, and sometime don't like to learn new things. And so on. I'm not going to guess how this breaks for smart versus not smart.
1 In some instances the dial that the user used to set the run-time was a mechanical clock and would wind back down also serving as the time-remaining indicator. Parsimonious design, that.
2 This is the sort of situation that prompted the third Smart Appliance rule. That dryer is very useful even without the app. Indeed, we've never used the app. Mrs. NoSwampCoolers tells me she has used the app for the matching washer (with a very similar control panel) once in the fourish years we've owned these things. Once.
3 Yeah. I'm just assuming there is a computer in there. My sense of it is that no one is designing these machines with end-to-end analog circuits anymore. I once did a few hours of analog diagnostics on a Kenmore model 40, but I'd expect to find a MCU behind any reasonably modern control panel.
4 My car's entertainment center has a SD card slot hidden behind a pop-up panel.
5 If they don't we're talking an additional up-front cost for them, but if they can afford the appliance, ... well Walmart's website lists tablets starting from under US$50 as I'm writing this..
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