Blog: Expect the Unexpected with Control Systems
Article By : Max Maxfield
The designers never considered what would happen if someone activated the locking mechanism whilst the fridge was already in the process of dispensing water.
Do you recall my “What are the Odds?” column from about six weeks ago when I noted that two fridges in different locations of our house (one in the kitchen, the other in the garage) managed to fail within a few days of each other?
Following a couple of visits from the repair company, the system in the kitchen was fixed (happy face). Meanwhile, the unit in the garage has shrugged off this mortal coil (ironically, it was its cooling coil that bit the dust, as it were) and headed out to the next plane of its existence (sad face).
Here’s another question for you — do you remember my “User Interfaces: The Good, Bad, and Ugly” column in which I sang the praises of the folks who designed the control system for the Breville Toaster Oven purchased by my wife (Gina the Gorgeous)?
By some strange quirk of fate, this Breville Toaster Oven is located right next to the kitchen fridge, whose control system design — it has to be said — leaves something to be desired.
Just to keep us on our toes, a new problem began to manifest itself a couple of weeks ago. There’s a water and ice dispenser combo on the front of the fridge. The way this usually works is that you get a glass, push it against the paddle, and the water starts to come out. When you subsequently pull your glass away from the paddle, the water stops, or — at least — that’s what it’s supposed to do.
Actually, to be fair, this is the way it works most of the time. Every now and then, however, when you pull your glass away from the fridge, the water continues to gush forth (I’d swear that the flow actually increases).
This usually happens when you least expect it, like when you fancy a glass of water in the middle of the night and you don’t bother turning any lights on because (a) you don’t want to affect your night vision and (b) you don’t want to fully wake up. Unfortunately, having a jet of iced water hitting you in the navel, streaming down your legs, and pooling between your toes means that not fully waking up is no longer an option.
The first time this happened, Gina and I both happened to be in the kitchen at the same time (thank goodness), and we ended up performing a mini-relay race running back and forth between the fridge and the kitchen sink using glasses of water as the batons.
“Oh dear,” I thought to myself (or words to that effect). On one of these runs, through my tears, I observed that a hitherto unseen “Locked” annotation had mysteriously appeared above the regular “Cubed Ice” button.
This would have been a great time to look at the instruction book that came with the fridge. I wonder where we stored that book when we accepted delivery of the fridge 18 months ago. As a fallback position, on one of my runs to the sink, I grabbed my trusty iPad and had a quick Google while no one was looking.
Google informed me that pressing and holding the “Locked” button for three seconds would turn this function off. Being young and foolish, I assumed that this meant pressing the “Locked” annotation. It didn’t. Further investigation with a flashlight revealed an almost invisible “Hold 3 Sec to Lock” annotation located just under the “Cubed Ice” button, so I pressed the “Cubed Ice” button for three seconds and… nothing happened.
Eventually, after about 15 minutes of exhilarating exercise, pressing the “Cubed Ice” button for about 10 seconds had the desired effect. After collapsing on the kitchen floor gasping for breath for a while, we started to mop up the floor while experimenting with interesting word combinations to express our fridge-frustration feelings.
Initially, I assumed that I must have inadvertently activated the locking mechanism, but the same thing happened a few days later, and again a few days after that. I called the manufacturer’s service department, who asked if I’d tried cycling the circuit breaker in the garage. Now, you can call me “old fashioned” if you wish, but my degree in Control Engineering leads me to believe that if you have to cycle a circuit breaker in order to obtain a glass of cold water from your fridge, then something is lacking on the control system front.
I must admit that my knee-jerk reaction was, “What sort of raving lunatic would add a control to lock the water (or ice) on?” After a little thought, however, I realized that the intention of this button was to allow the parents of young children to lock the water (or ice) off.
All of which brings us to the point of this column (yes, of course there’s a point, how could you doubt me?), which is that the designers of this fridge obviously never considered what would happen if someone activated the locking mechanism whilst the fridge was already in the process of dispensing water or ice. My own experimentation has revealed that the fridge will happily continue dispensing away until the locking mechanism is deactivated. It’s unfortunate that, in our case, the locking mechanism (a) self-actuates and (b) doesn’t respond well to deactivation requests.
So, the lesson we can extract from all of this is to expect the unexpected. If the developers of this fridge had set things up such that the locking mechanism could not be engaged while the device was in the process of dispensing water or ice, I would have more hair on my head, I wouldn’t be afflicted with a nervous twitch, and I could cut down on my daily dose of Dried Frog Pills.
The fundamental interconnectedness of all things
As an aside, I’m working from home today because the repair man came earlier to look at the fridge. He was a really nice guy who used to work in the aerospace industry designing safety-critical systems on rockets. He tried retiring when he was 53, but quickly realized the fatal flaw with this plan, which was that all of his friends were still at work. As a result, he had no one to hang out with apart from his wife, who already had an active social life with her friends, which is how he came to find himself in my kitchen repairing my fridge. (Now I can boast that I have rocket scientists to repair my fridge.)
When I explained what was happening, he said, “It shouldn’t do that.” Ha! I knew it! He then recapped the KISS principle (“Keep it Simple, Stupid”) and opined that modern engineers had a tendency to add functions in “because they could” without fully considering all of the ramifications of their design decisions.
We stood quietly in front of the fridge nodding our heads together whilst pausing for a moment of reflective silence. Eventually, he said, “Don’t worry, it’s an easy fix. All I have to do is swap out a small control board, which will only take a couple of minutes.”
“Do you have one with you?” I asked, optimistically. “Of course not,” he replied, jovially. “I’ll have to order one and come back next week.” Oh well, at least he was nice and said it with a smile. Meanwhile, I will keep my Sou'wester, waterproof coat, and galoshes on standby for when I next feel the desire to dispense a glass of iced water.
Moving on… did you ever read the Dirk Gently stories — Dirk Gently's Holistic Detective Agency and The Long Dark Tea-Time of the Soul — by the late, great Douglas Adams? If so, you may recall that Dirk bills himself as a "holistic detective" who makes use of "the fundamental interconnectedness of all things" to solve crimes.
Well, as my own personal example of the fundamental interconnectedness of all things, just after I started writing this column, Gina — who was on the phone to her mother — shouted “Mom likes your column on our problems with the fridge.”
As you might imagine, this gave me pause for thought. My own mother’s memory is so good she occasionally remembers things that haven’t even happened yet, but even she hasn’t gone so far as to offer preemptive comments on a column that I’m still in the process of writing.
As it turned out, Gina’s mother, Jan Jackson, had just stumbled across my original “What are the Odds?” column. I mean to say, come on, what are the odds that she would do this while I’m in the process of writing the follow-up?
Furthermore, I am informed that Jan has shared the original column with Gina’s aunts and uncles in Louisiana, and now it seems that everyone is waiting for me to finish and post this current offering, so here’s a shout-out to Jan, her sisters Pearl, Kat (and her husband Ed), and Ronnie (and her husband Mike); also her brothers Paul, Johnny (and his wife Sherry), and Robbie, whose birthday is tomorrow (and his wife Debbie).
Gina’s grandmother was one of ten siblings and — as you can see above — Gina’s mother is one of seven, which basically means that Gina can count half of Louisiana amongst her relatives. I just realized that this means this column is going to get a lot of page views, so — if you’ll excuse me — I’d better dispatch the butler to retrieve my dancing trousers and commence my limbering-up exercises prior to performing my Happy Dance.
In the meantime, as always, I thank you for perusing and pondering my meandering musings, and I welcome your thoughts and comments pertaining to control systems and the designers thereof.