In praise of K.I.S.S.

If you’re not familiar with engineering, the above phrase might make you think I’m about to sing the praises of an aging metal band. But in engineering circles, “K.I.S.S.” is short for “Keep It Simple, Stupid”. It means that the simplest solution to a problem is usually the best.

Unfortunately, like every other field of endeavor, engineering has fallen under the siren spell of automation.

Take aviation.

The first aircraft flew by direct control. The pilot pressed on the rudder pedal, and a cable connected to it moved the rudder. There might be a few connecting links in between, but there was a direct connection between the pilot and their plane. As aircraft grew in size, the ability of pilots to move the ever-larger control surfaces meant that it became necessary to add ‘boost’ to the controls. Think of power steering in a car: you turn the steering wheel, and a linkage tells the wheels which way to turn and how much to turn. At the same time, a hydraulic cylinder senses the direction the wheel is being turned and applies force in the same direction, taking some of the load off the driver. But beyond the added pressure to make the action easier to undertake, there’s still a direct connection between the pilot’s (or driver’s) actions and what happens.

Now, however, most modern airliners have migrated to a system called “fly by wire”. Originally pioneered by the military for high-performance fighters, fly by wire has no direct connection between the pilot and the aircraft’s control surfaces. The actions of the pilot are registered as electrical impulses that are interpreted a computer, then transmitted to the control surfaces. For an aircraft like an F-16, which is designed to be unstable so it is more maneuverable, having this interface means that the computer know how much to move the control surfaces without causing the aircraft to go out of control. And because it must know how much a control surface can be moved without causing the aircraft to go out of control, it also means that the computer gets a ‘vote’ in how the aircraft is flown. In other words, if the computer thinks the input from the pilot is too extreme, it will over-ride the pilot and undertake a maneuver as close to what the pilot desires as it deems safe.

Translate that to an airliner, and you get computers that think a pilot pulling back on their control yoke to avoid a terrain feature is too extreme, resulting in the airliner full of passengers slamming into the ground. Worse, if the software is improperly coded, it can even result in a normal control surface input being deemed ‘unsafe’, resulting in a crash. The latter is what happened with the Boeing 737 MAX, and Boeing is still struggling to both fix the problem and regain the trust of airlines.

Unfortunately, the concept of fly by wire is making it’s way into the auto industry. Many modern autos no longer have a direct connection between any of the controls the driver uses and the auto itself. When you push in the accelerator, you don’t move a linkage that feed more fuel into the engine. Instead, your input is read by the auto’s onboard computer, which in turn sends a command to increase the fuel flow to the engine. Even the steering wheel is often no longer connected to the wheels is is supposed to control.

Right now, someone is reading this and saying to themselves “So what? As long as it works, why do I care?”

I’m glad they asked. My sister owns a modern piece of American auto engineering, an SUV I call her personal tank. It has all the modern bells-and-whistles: variable fuel feed to the engine cylinders to increase gas mileage, active traction control, automatic brakes, the works. All of this is controlled by an onboard computer, which also monitors the health of the vehicle and all it’s systems. And in that latter function lies the rub.

The onboard computer recently informed my sister that one of her wheel bearings had worn beyond the design specifications and needed to be replaced. And because the wheel bearings interact with the vehicle’s brakes, this caused her to experience locked brakes if she applied too much pressure too fast. All this happened on her way home from work, but she managed to nurse the vehicle home and drop it off at her favorite mechanic’s shop. A couple of days (and several hundred dollars) later, the mechanic gave her tank back to her, having replaced the wheel bearing assembly.

As I’d been giving her rides to and from work, I was quite happy to drop her off at the shop. What I wasn’t happy about was to learn, later, that her SUV had begun experiencing the same problem before she got home. She took it back to the shop, complained, and the mechanic put it back on the rack and started testing. He could find nothing wrong, the bearing in question reacted like it was in proper order, so he reset the vehicle’s computer and told my sister that a bad sensor might be sending a false signal to the computer.

Back home she goes, only to have the fault reappear.

So, I go on double duty. First, I drive her to work, then, after I return, I take her car out to the mechanic to be tested. It was decent walk back, the air cool and not a lot of wind…but getting the vehicle to the shop was not easy. Because it was convinced that there was a serious fault in the vehicle, the onboard computer was not happy with it being driven. So, no matter how much pressure was on the accelerator, the SUV staggered along at only five to ten miles per hour. As I couldn’t find the emergency flashers, this resulted in many people ‘flipping me off’ due to my slow speed.

But it’s there, and I’m home and happy to have my ‘primitive’ car to drive: manual transmission, direct link between accelerator and engine, and minimal interference from any computing devices. If I could have found my vehicle with ‘crank-up’ windows, rather then the power windows it has, I’d have been even happier, but beggars can’t be choosers, as the saying goes. It is a car that keeps to the idea that the simple solution is often the best, and I think auto makers would be well served to remember that dependability is often valued more by drivers than style or ‘modernity’.

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